There seems to be no brightness control on the flyback transformer unit ....mmm. The monitor I performed this adjustment on was a 21 inch Hitachi CM823F.
However I found a service manual for a Sony GDM-FW9012 which uses the same G1W chassis as the GDM-FW900.
There is a high voltage adjustment resistor (potentiometer) located apart from the flyback transformer.
In the service manual, it is on page 6- Section 4.1 - Block Digrams, and is component RV901 located near the flyback transformer, in the 'D' (Deflection) block.
I have no idea how to adjust it safely or otherwise. It does appear to be similarly configured as the focus adjustment potentiometers on the flyback transformer.
Thanks Rice Burner for that link. I found the manual for my Dell P992 on that site http://fileshare.eshop.bg/downloadsm/6058/Dell_P992.html
Trouble is it doesn't mean much to me. I've read on this thread that the P992 doesn't have that infamous resistor that you can change to reduce the brightness.
Can you think of a solution for a P992 from this manual???
Thanks for that. I wonder how similar my W900 is to the FW900 - probably completely different knowing my luck! I don't feel confident enough to touch anything classed as 'high voltage! I've had enough electric shocks in the past - not an sensation I enjoy!
There may be way to adjust the high voltage potentiometer whilst the monitor is not live.
Have the monitor turned off, but leave it plugged into the wall with the wall switch off. The high voltage anode can retain high voltages for some time until the residual charge leaks away.
I would leave any incremental adjustments for the following day.
The high voltage adjustment can be made while the CRT is neutral. Turn the potentiometer one way or the other, in a small increment. Anticlockwise is usually down, so thats the way I would go initially. You will find out if thats the right way to go once you turn the monitor back on.
Also, use a multimeter to establish the resistance being calibrated, to make your adjustments consistent and repeatable. The high voltage potentiometer has a resistance range of 100 K-Ohms, so an ordinary multimeter will be sufficient. This assumes contact points for the multimeter probe can be found around the potentiometer. One side of the potentiometer is at earth (chassis) potential, so one multimeter probe can be referenced to any part of the earthed chassis.
Here is an article regarding brightness adjustment:
I've read on this thread that the P992 doesn't have that infamous resistor that you can change to reduce the brightness.
Can you think of a solution for a P992 from this manual???
Thanks
len
Looking at your monitor schematic, the P992 does have the HV adjustment through potentiometer RV901 (code for variable resistor Tube Type 901).
It seems these monitors have the HV potentiometer adjustment option at RV901. Generally, CRT's work on similar principles, so there must be a HV adjustment somewhere.
Can anyone help me with my GDM-W900. On dark background you can see retrace lines and picture is slightly reddish. If I adjust color settings(R,G,B Bias and Gain) to zero, some of the retrace lines fade but some are still visible.
There is a service port behind the monitor(looks somewhat S-video port but there is place for 8 pins in three rows). Where can get service cable and software(or is WinDAS appropriate)?
I have opened monitors casing and I found one potentiometer for picture focus. Could there be more hidden somewhere? Also noticed that I cant use Hutzelmans instructions for brightness modification because this monitor uses different circuit board.
the cable is mentioned. It ends in the 8-pin mini-DIN. I suppose one could make a cable like the one described earlier in this thread, substituting an 8-pin mini-DIN for the monitor end of things.
My best guess for the pinouts is listed at:
Having opened up the monitor and found the module, it only has 2 screws both of which seem to affect focus. On the tube itself is a large grey module with large wheels to adjust: TLH, APH, XCV and XBV along with screwdriver adjustable YBH, YCH and TLV. Any idea if one of these affects the brightness? I don't really want to start fiddling around with them in case I damage something or do something I can't correct.
All those labels end H or V. My guess is that being on the tube they all stand for "Vertical" and "Horizontal" nothing to do with brightness?
len
So might it be just a question of tweaking this potentiometer (observing usual precautions)?
len
If you can find a G2 option, whether by a control signal or a modification of some kind, then it is the preferable way to go.
The master brightness control, if it can be found, is the way to go.
I was lucky with my Hitachi CM823F in that the brightness/screen G2 adjustment was integrated with the flyback transformer. I could remove the rastering easily, and likewise control the overall screen brightness.
The G2 voltage is generally in the order of 500-600 Volts, as opposed to the High Voltage Anode in the CRT being 25kV to 30kV. There is way more scope for tuning and control with the G2 than the HV.
To avoid the hassle you are having with the P992, it may be better just to buy another monitor for $50 to $100 with adjustments which are better known and more serviceable if needs be. Sorry if this is an uncool thing to say on this forum. :smiles:
Compare and contrast the attached marked-up circuit diagrams. It appears the modified resistances must be lower than standard value to reduce brightness.
Please refer to other threads in this forum for information, Thanks.
Brilliant RiceBurner!
Thanks on behalf of us P992 owners.
So what order of Resistor do you think I should use to replace (or solder in parrallel with) R 941 ?
Thanks
There you go, has the layout for the p1110 in there...
Second... The 457 and 459 are really close to each other. I have 2 other buddies with this monitor... They bought it back in 2002? I think... On the same day... some sale. 1 of them did a parallel 10 ohm to the 457... The 457 runs under the board like the 459 does before you cut it... He ran another 10ohm on top of the board to the 457 points making it a 5ohm in all connection I believe... Or close to it. Also these 2 points being very close makes it very easy to make a mistake or accidentally drag your soldering puddle and connect the 457 and the 459. I did this... and then remelted the 459 and with a knife ever soo carefully(not the cut or destroy the circuit that ran on the board between 457 & 459) separated the 2 again.
---I read a couple of posts where people thought they may have connected the 457 and 459 points and couldn't get out of the too dark phase at all... This is a situation I ran into... Or so I thought.......
Lastly, My final BIG mistake... The 1 that made it or broke it... When you go out shopping for these resistors... make SURE it's a M resistor... On my set up and my other buddies set up... We both bought 5.6ohm 1w resistors.. Neither worked for either of us. So I bought 5.2ohm, 6.2, 6.8. 9.1, 7.2, 7.8?,10, 11.2? and many more up to 15... and as low as a 4.7. All 1 watt resistors too... ALL gave me too dark results. Either WAY too dark so that all settings/colors on full blast wouldn't hardly give me an image... Or just too dark giving me a brown tint on everything while all settings were turned up. I couldn't figure it out...
I was soo close to trashing this beast... Sure that I probly connected or over burned 2 points with the soldering iron...
Until... I returned to my local computer hardware store... I found out there was actually 2 sections of carbon film resistors... I looked at the resistor stripes and noticed they were different... Began reading and OH NO I didn't buy the M resistors... I bought 2 of each all the way from 4.7 to 9.1. ALL 1watt and ALL M RESISTORS. I returned home, sure I had the fix now. And sure enough, I was correct. My first and final attempt was a 5.6Mohm 1 watt carbon film resistors (also important to get a carbon film and not a metal film or whatever b/c it'll send out some signal or radiation crap). This could also be marked as a 5M6 ohm 1 watt... I use a 1 watt b/c I hear that a few years down the road I'd just be replacing the 1/2 watt or the 1/4 watt if I were to choose one...
The 5M6ohm works GREAT, contrast/brightness are at 50/50 and I no longer have to use my nVidia settings... It's amazing. My buddies monitors had went out about the same time within a month of each other... And my boss gave me my p1110 and it already had the brightness issue... The resistors at the store me and my friends shopped at costs me like 4cents each resistor... 100 resistors for like 4$.... A free monitor that was several hundred dollars... now 4 cents... Amazing. Me and the guys all stumbled into the M resistor problem... Even when my friend ran his parallel to p457. We didn't share our results till the end seeing how I guess it turned out to be a challenge to see who could fix it right and the fastest way... In the end we were all fools... But successful fools.
I have never soldered anything in my life until recently... It's fun. I'd take the job in soldering if I hadn't already had a good internet job.
The software fix... Way too complicated, find the software... the links most of you listed don't work, splice the cables... set the monitor to the right adjustments... Ugh... Too much to worry about.
With the resistor fix just disassemble the monitor, remove the old resistor, solder in new (easy/fun), remount case, play/enjoy. 10 minute deal.
A few precautions to worry about. Don't go disassembling the WHOLE monitor. Many pieces actually hold a charge and can/WILL kill you if you touch them. I touched all over the board where the 457/459 are and nothing jolted me. Maybe I was lucky...
Follow these instructions... VERY easy, and I guarantee everyone has a hardware store or warehouse around you that carries resistors... Everything needs em. Radios, TVs, computers... toasters now even... etc. No need to worry about ordering them online, just google some resistor retailers in your area... I did. And GREAT SUCCESS!!!
psychoninja911@yahoo.com is my email address so email me if you got anymore questions I should be able to help
Until next time...
--CHRIS!!!
Does anyone know if this will work on the IBM P260 or is it different?
I just fixed two IBM P260's. One had a very bad green tint instead of black. The other had a bluish tint instead of black (although it was not that bad) and I added a 10-Megohm (1/4 watt) resistor in parallel to the other 10-Megohm resistor and it worked perfectly!
My brightness on one monitor is at 75/100 and on the other it is 49/100 and it looks great! Black is finally black again!
The one with the green tint still had a green tint over everything and I could not fix it through the menu, but I was able to fix it through the Nvidia Control Panel without much hassle.
Now both monitors look almost identical and also show very good greyscale performance after configuring.
They do seem a little on the dim side but I would much rather have good black levels and a bit dimmer picture.
Thanks to this awesome thread and people who like to experiment, I now have revived my old monitors for just one dollar and about 1 hour of time! Amazing!!
Thanks on behalf of us P992 owners.
So what order of Resistor do you think I should use to replace (or solder in parrallel with) R 941 ?
Thanks
Len (Eljay)
The p1110 and p992 marked-up circuit diagrams have been revised to make the similarities clearer.
The main similarity between these two diagrams is the voltage divider circuit outlined in green. This is likely to be important for G2 voltage regulation.
Before commiting any resistor changes, confirm the circuit diagram is correct and check the resistor with a multimeter for the correct resistance value.
For practical reasons, the parallel resistor modification is not recommended. The parallel resistors need to be very large and may not be readily obtainable. A 100M parallel resistor will give 18M.
The 22M high voltage resistor will need to be replaced with two high voltage resistors in series. If one of the resistors is 12M then the other resistor can be the same as the P1110 mod resistor (these are usually between 4M and 7M depending on the level of over-brightness being experienced).
The middle connection for the high voltage series resistors needs to be electrically isolated from the main board, to prevent short circuits. There is space on the board to properly place the resistors away from nearby circuitry as well.
The series resistors should be lightly soldered in place for testing purposes. The arrangement can be made permanent once the brightness problem is resolved.
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W900 owners! I have found a supplier of the 'monitor to PC interface cable' here in the UK. A company called Seme Nedis Ltd sells it for £33 about ($66). I'm going to buy one and see if I can fix my retrace issue. I'll then try to sell it afterwards if anyone wants it.
Just got a Sony E500. Eric's resistor trick works wonderfully!
( http : // eric.hutzelman.com / articles / 1 - Sony - CRT - Brightness - Fix ...remove spaces... I totally understand the spam guards being in place, I'm simply paying respect to this person's article)
Will probably tweak a bit more, but it's looking great compared to what it was (super bright, scan lines...).
Simply unbelievable that this ol' thing can look mostly right again.
Went with two 2.2M Ohm, 1/2 watt resistors in series (4.4M Ohms total).
Probably going up to around 6M would be optimal, as others have mentioned. Will have to hunt down a good single resistor - I'd rather not have three in a row.
Still, they were worth the $1 from RadioShack (all they had in the Megaohms range were 1, 2.2, and 10...). ...Probably have to visit a local shop to get anything else...
Reprogramming these things sounds fun and all, but for me, soldering was a fun solution. Eventually, I think I might try the other route, but for now, this is just great that it works so well.
Still a fan of these monitors after all these years... Newer LCDs are finally starting to catch up to tube quality, but these things were probably some of the best monitors ever made.
Just wanted to thank everyone here for all the great posts on the subject of fixing these monitors. Made my day to land upon this monitor, find this thread, and then actually get this thing looking good!
W900 owners! I have found a supplier of the 'monitor to PC interface cable' here in the UK. A company called Seme Nedis Ltd sells it for £33 about ($66). I'm going to buy one and see if I can fix my retrace issue. I'll then try to sell it afterwards if anyone wants it.
You say the picture is perfect besides retrace lines? If the retrace lines were visible because of excessive G2 the picture would be un-bearable by anyone's standards.
This probably isn't the simple G2 adjustment. Neither will the cable be likely to help.
It's a know issue with the blanking hardware in the GDM-W900.
As some have been replacing resistors, you may need to replace some diodes and transistors on the A board with improved components.
D1806 DIODE 1SS376TE-17
D1807 DIODE 1SS376TE-17
D1808 DIODE 1SS376TE-17
Q1804 TRANS 2SA1162-G
Q1806 TRANS 2SK1849-TB
Q1807 TRANS 2SC2780-NK
Attached is a schematic of where these parts are located on the conductor side of the A board.
This information was from a Sony Service Bulletin, I haven't verified it on my own, but it sounds like you have the same issue.
If you buy the cable, could you describe what pins go where and how the cable is built. I realize this may be counter to your goal of selling the cable.
If you have the issue I described though, you'll need to open up the monitor anyway, and may as well just figure out where the pins go than buy the pricey cable.
TLH, APH, XCV and XBV along with screwdriver adjustable YBH, YCH and TLV
The adjustments on the CRT yoke deal with convergence, purity/landing, and geometry. I wouldn't recommend changing them unless you know you need to.
Brightness is adjusted on the flyback, or on the board with the actual CRT socket. Assuming you mean G2 or screen grid voltage.
There are other tube factors that play into spot brightness, since it's a function of beam density,velocity, landing and phosphor efficiency.
Now, this isn't very helpful unless you know what factors control the above mentioned factors. I haven't found a lot of material about this. I did find a recent book about phosphors though, I'll have to request it at my library.
I found this supreb thread, I have 1 year with the same problem, i never imagine that my monitor can be fixed, my monitor is not the dell P1110, is the sony CPD-E400. I downloaded the windas files and programs and tested in my desktop and do not work, then I copy the files to my laptop and I get the same error, when start the programa some error occurs:
How can I fix this? Im sure I have all the dll´s and files, can some one rar the windas and send it to my mail or upload it to rapidshare?
Or some one that successfully fixed the same monitor and used with Windows Xp Pro Sp2 give some clues!
after i can run windas i will star to build the cable !
cheers!
Henn
Mexico city
Did you follow the instructions exactly?
What's the file size and version of your RegDLL ? (88k.. I don't have a copy of winDas available to check if this is correct)You need the exact one mentioned in my installation instructions. No other will work.
Most Google links say this error is caused by a corrupt DLL or an incorrect version.
I've done this on XP sp2, so it's likely not an XP related issue.
Compare and contrast the attached marked-up circuit diagrams. It appears the modified resistances must be lower than standard value to reduce brightness.
Please refer to other threads in this forum for information, Thanks.
P1110 Modification
P992 Modification
What other threads?
Oh, and um, this is by far the most interesting post I've seen. I can't figure it out though.
Would you be so kind to give a more verbose explanation of how it works?
How did you know a P1110 is a G500?
How did you know what a P992 is, and thus find it's service manual?
So, with the FW90** series, even the HP, SUN, SGI branded models still say the GDM-FW9012 or whatever.
On the Dell, HP, Compaq P1110, P991, P992 etc. the sony GDM or CPD model number would still exist wouldn't it? How would I find it?
Just looking at where the hi voltage to the G2 is taped, I'd guess the voltage there is controlled by how much current passes through the other taps that lead to more complicated arrangements with amps and transistors, thus changing the voltage drop across those resistors.Or have I got that wrong?
What exactly do the amps and transistors do? I realize that a line from the CPU comes in with a signal, which some how varies what the amps and transistors sink from the G2 line.
You say the picture is perfect besides retrace lines? If the retrace lines were visible because of excessive G2 the picture would be un-bearable by anyone's standards.
This probably isn't the simple G2 adjustment. Neither will the cable be likely to help.
It's a know issue with the blanking hardware in the GDM-W900.
As some have been replacing resistors, you may need to replace some diodes and transistors on the A board with improved components.
D1806 DIODE 1SS376TE-17
D1807 DIODE 1SS376TE-17
D1808 DIODE 1SS376TE-17
Q1804 TRANS 2SA1162-G
Q1806 TRANS 2SK1849-TB
Q1807 TRANS 2SC2780-NK
Attached is a schematic of where these parts are located on the conductor side of the A board.
This information was from a Sony Service Bulletin, I haven't verified it on my own, but it sounds like you have the same issue.
If you buy the cable, could you describe what pins go where and how the cable is built. I realize this may be counter to your goal of selling the cable.
If you have the issue I described though, you'll need to open up the monitor anyway, and may as well just figure out where the pins go than buy the pricey cable.
Good luck either way.
Thanks for that - I'm getting closer to a solution!
I ordered the cable but may try to cancel it now. Funnily enough, a photo of the A board appears in a post on p13 (I think) of this thread. Those components look terrifyingly small. When you say 'improved components' I'm not really sure what I should be looking for. I googled the serial numbers and I can find replacements with those numbers online. Should I just buy those?
Annoying that Sony's monitor helpline was unable to tell me that this was a known issue. Obviously they 'forgot' to update their database.
I read most of the pages in this thread and I would like to try the Windas approach to fix my Dell P1110 brightness issue. I have never done any soldering and I don't have any soldering kit. So, where can I get cheapest RS232<>TTL converter thing (just ready to use one)?
Thanks for that - I'm getting closer to a solution!
I ordered the cable but may try to cancel it now. Funnily enough, a photo of the A board appears in a post on p13 (I think) of this thread. Those components look terrifyingly small. When you say 'improved components' I'm not really sure what I should be looking for. I googled the serial numbers and I can find replacements with those numbers online. Should I just buy those?
Annoying that Sony's monitor helpline was unable to tell me that this was a known issue. Obviously they 'forgot' to update their database.
Yes, the list was of the improved components, I didn't list the originals. Infact, the service bulletin didn't either, I'd have to look into the parts list to see what they were.
Are the parts expensive? I'd imagine shipping would be most of the cost, but I haven't looked them up.
De-soldering and soldering small surface mount stuff is a pain.
Nice that you found a picture of the A-Board! I totally forgot about that. Poor guy who put it up never had his problem solved, as he couldn't get that cable or it's pin-out.
So... yeah.. um, I was hoping they were through hole components, too bad theiy're not.
I've done surface mount components only once before. I wish I would have had a magnifying glass, a sharper soldering iron point, and a good solder wick. Still managed to get this cap back on, no idea if I heat damaged it or not, at least I didn't create a solder short.
Then, how could you know you put it all back together the right way? Would turning it on with a botched 'repair' break more things?
With a cheap multimeter, it'd be pretty obvious whether or not you had the diodes back in and working correctly. There may be more ways to test the transistors, but at least you could confirm you didn't short anything.
If you have the multimeter, solder, flux, soldering iron and some time to check out transistors on Google, I think you'd have a good chance. The alternative being to put up with the retrace lines.
Heck, this might not even be your problem. I just brought it to your attention because I thought it sounded more like what you were describing.I'm just going by what you said and my questionable ability to match the symptoms. I don't want to recommend something I can't say for certain will fix it.
I read most of the pages in this thread and I would like to try the Windas approach to fix my Dell P1110 brightness issue. I have never done any soldering and I don't have any soldering kit. So, when can I get cheapest RS232<>TTL converter thing (just ready to use one)?
Thanks.
Eh, I'd just go for the cable from massmind. It's cheap and ready to use if you ask them for the Windas pin order (easy to switch yourself without tools). If you want support and don't mind paying a little extra, I'd go with Xweebie and Emusicraft.
If you want USB, some one else made a post about it. I've echoed it once I think, maybe on some other forum.
I have an updated version of the howto sitting on my hardrive... it's getting to be too late now to release it. The site traffic is going down. I still want to get all the circuits, the CRT, and the color stuff explained precisely. I may not finish it all in time.
If anyone knows any good books on this topic, let me know, as it's hard to find quality info on the web unless you're smart enough to work everything out from something as basic as Coulomb's law.
first i would like to let you know thta i think it AWESOME how you have dedicated time and helped many many many people fix there potentially beautiful monitors rather than throw them away because of the brightness problem , or other related issues that make the monitor unbarable
and i myself am another victim of the unbarable brightness issue with the dell p1110, i originally bought it used on ebay(stupid me didnt do any research about it tho) for a little over $100 w/shipping and thoguht it was just too good of a deal...until i got it and booted it up and discover the awful p1110 brightness issue(luckily the seller had a 7 day return warranty, so i told him about the issue and such and he refunded me for the monitor AND shippng AND told me not to even send it back, just keep it)
so now i got a free giant 21" monitor with the potential to make perfect looking again by spending about $10 bucks and doing a little researching online(as how i ended up here:P)
now i know there are 2 methods to go about this
either buy a 4-6 ohm r459 resistor and do a lil soldering
or buying the "rs232 to ttl 5v converter kit" and using the windas program to change the G2 voltage or something like that(and this is the method i am choosing to do since i REALLY dont want to pry open the monitor and solder and mess around with the insides of it)
now i was reading ur tutorial for thw windas method on ur geocities page, and trying to read a lot of that stuff really mind boggled me, and i have a to tight of schedule in my life right now to really learn the ins and outs about it(but obviously im going to push my self to learn the basic knowledge of it so i can atleast do it)
i was planning on buying the one kit thier selling on ebay(cant post a link cause im a new member) its the only one that shows up when u search "RS232 TTL 5V converter KIT", besides the windas program, is this all i need to do this, or are there extra cables i need to attain?
is it real complicated to set it all up? is there like any step by step guides that have pictures included, or step by step guides for dummies to do this? because a lot of the stuff in ur tutorial is way over my head
looking forward to a response from you, and thanks for all ur time
well after doing a lil more research on this windas solution, im still pretty confused , i defintly plan to buy a pre built adapter such as one of the following...
or one of the other ones on ebay, but my question is, what the heck do i use to connect this contraption from my pc to my monitor, and where heck to get these cables/wires
and how do i know which specific pin on the adapter connects to what specific pin on the back of the monitor?
any answers would be MUCH appreciated
and im sorry if the answers to my question are lost somewhere on this thread, but this thread is so BIG lol
ill continue to read through this thread when i got some free time but if anyone can answer my questions, that would be GREAT
What exactly do the amps and transistors do? I realize that a line from the CPU comes in with a signal, which some how varies what the amps and transistors sink from the G2 line.
Thanks for any help and explanation.
The attached schematic diagram illustrates the basic operating principle of the G2 grid voltage control circuit.
The G2 grid voltage is determined by the voltage drop occuring through the load resistor connecting the high voltage supply to the G2 grid.
The required G2 grid voltage is achieved by drawing a sufficient current through the load resistor from the high voltage supply.
The operational amplifier compares the G2 reference voltage to the G2 grid voltage sensed and it outputs a corrective voltage which controls the net sinking of current through the transistor and load resistor.
The critical aspects of the circuit for determining the G2 grid voltage, and hence screen brightness level, are as follows:
[1] The G2 reference voltage signal at the positive input to the operational amplifier must be stable and at the correct voltage level. This assumes the OSD control chip puts out the correct pulse-width-modulated G2 signal, and this signal is correctly rectified to the G2 reference voltage needed for the operational amplifier.
[2] The voltage divider resistors between the G2 grid and ground must have the correct resistance values.
[3] The high voltage supply must be greater than the desired G2 grid voltage.
[4] There should be no significant extraneous currents causing bias voltages in the voltage divider. For instance, the feedback current from the amplifier passes through the smaller dividing resistor on its way to ground. This causes a small bias voltage within the resistor which results in the G2 grid voltage being reduced by about 10 Volts or so.
The NON - CRITICAL aspects of the circuit for determining the G2 grid voltage, are as follows:
[5] The stability of the high voltage supply is not critical to the G2 grid voltage because the amplifier can compensate for the voltage variations, by controlling the current sunk through the load resistor.
[6] The change in performance characteristics of the power transistor with temperature or current is not critical because the amplifier can compensate for these variations too.
CONCLUSIONS
There are three ways to fix an overbrightness issue caused by excessive G2 grid voltage.
[1] Decrease the G2 reference Voltage signal appearing at the operational amplifier (Windas Method - Known)
[2] Decrease the "high voltage" resistor's resistance (Resistor Mod Version 1 - Known)
[3] Increase the "low voltage" resistor's resistance (Resistor Mod Version 2 - Not Known .... apparently)
This alternative resistor modification, could result in a potentiometer being used as a "screen brightness pot".
MEASURING G2 GRID VOLTAGE
There is a simple indirect method to estimate the G2 grid voltage.
Measure the G2 Reference Voltage, and multiply by the resistor ratio in the voltage divider.
Example. VG2 ref = 2.70 Volt, R1 = 100 KOhm, R2=20 MOhm
VG2 grid = 2.70 x 200 = 540 Volt.
Hi Guys, I lurked here long time ago when u were all talking eeprom mods and i must say it seemed to be a duanting task!
I have the Dell P992 screen which is in exellent condition....other than the high brightness level ofcourse :rolleyes2
So now I see u guys have a resistor mod available, which I'm certainly willing to undertake, though what I would very much appreciate is a picture of the board and the highlighted resister as seen on http://eric.hutzelman.com/articles/1-Sony-CRT-Brightness-Fix website. This would make me feel alot more confidant seeing exactly where i should be on the board and such.
If successful I also have another screen to do as I recommended my young cousin to buy one not too long ago..
These screens are just too good not to be used, and a big thankyou to all who have contributed here so far, well done guys :cheers3:
Excellent thread for a serious problem. Can't believe SONY couldn't figure this one out since the time this issue exists. Anyhow, I have 2 monitors with 2 very distinct problems. My first monitor is the P1110 from Dell, it has the too bright issue. I have my brightness set at 0 and contrat set at 100. At that level, the image looks normal, but the blacks are a little more like dark grey (at that setting!). I found the Hutzelman fix a couple days ago, so I wonder if I just try that one out, because I don't think I can do the cable to connect to the P1110 as I have no clue where to start. I've seen the USB cable in this thread, does that really work? I mean, you split the cables and rewire the other end to plug it in that 4 pin connector in the P1110 monitor?
My second monitor is a P1130. The problem with that one isn't the picture, as it is ACE!!! But, the monitor emanates this quite toxic smell from the core of the tube. What to do??? The monitor is not overly hot, and the smell is comming out at a constant rate and can be perceived as discrete but with my windows closed in the room, it can get too polluted with this hazy smell.
Hello and thank you to everyone who has contributed time & talent here! I've read all 45 pages.<O:p</O:p
<O:p</O:p
I own a Sony CPD-G420 monitor. I need to be able to adjust the convergence of the red & blue signals INDIVIDUALLY. As you may know, the OSD controls on the front of this monitor allow you to adjust the red & blue signals SIMULTANEOUSLY. That is, as you change the value in the OSD, the blue & red beams move towards or away from each other. There is a horizontal control and a vertical control. Unfortunately the points where the blue & red meet do NOT coincide with the green beam (either horizontally or vertically). It's very close, but I still detect the slight fringe on text & fine lines. This small error is consistent across the whole display.<O:p</O:p
<O:p</O:p
Before I invest the time & money in getting the RS232 – TTL cable & setting up the WinDAS software, I hoped to confirm that this INDIVIDUAL adjustment of the red & blue convergence will be possible on a Sony G420 monitor. From some comments in the thread, there seemed to be some Sony models that might not support this in WinDAS. Has anyone done this individual convergence adjustment on a G420, or knows for sure that it is possible via the software? Or am I destined to have to deal with mechanical & magnetic adjustments inside the monitor? Thank you very much for your input.<O:p</O:p
<O:p</O:p
The colors of the Sony monitor are gorgeous, but I think I’ve been spoiled by the perfect convergence on my ageing .25mm dot Nanao monitor. That’s making me want to get it right on the Sony as well, if possible, as I also work a lot with text.
Comments
I checked a couple of things out.
There seems to be no brightness control on the flyback transformer unit ....mmm. The monitor I performed this adjustment on was a 21 inch Hitachi CM823F.
However I found a service manual for a Sony GDM-FW9012 which uses the same G1W chassis as the GDM-FW900.
It can be found here:
http://fileshare.eshop.bg/downloadsm/2778/Sony_GDM-FW9012_G1W.html
There is a high voltage adjustment resistor (potentiometer) located apart from the flyback transformer.
In the service manual, it is on page 6- Section 4.1 - Block Digrams, and is component RV901 located near the flyback transformer, in the 'D' (Deflection) block.
I have no idea how to adjust it safely or otherwise. It does appear to be similarly configured as the focus adjustment potentiometers on the flyback transformer.
Good Luck.
http://fileshare.eshop.bg/downloadsm/6058/Dell_P992.html
Trouble is it doesn't mean much to me. I've read on this thread that the P992 doesn't have that infamous resistor that you can change to reduce the brightness.
Can you think of a solution for a P992 from this manual???
Thanks
len
There may be way to adjust the high voltage potentiometer whilst the monitor is not live.
Have the monitor turned off, but leave it plugged into the wall with the wall switch off. The high voltage anode can retain high voltages for some time until the residual charge leaks away.
I would leave any incremental adjustments for the following day.
The high voltage adjustment can be made while the CRT is neutral. Turn the potentiometer one way or the other, in a small increment. Anticlockwise is usually down, so thats the way I would go initially. You will find out if thats the right way to go once you turn the monitor back on.
Also, use a multimeter to establish the resistance being calibrated, to make your adjustments consistent and repeatable. The high voltage potentiometer has a resistance range of 100 K-Ohms, so an ordinary multimeter will be sufficient. This assumes contact points for the multimeter probe can be found around the potentiometer. One side of the potentiometer is at earth (chassis) potential, so one multimeter probe can be referenced to any part of the earthed chassis.
Here is an article regarding brightness adjustment:
http://stason.org/TULARC/pc/video-faq/45-Brightness-Adjustment.html
Looking at your monitor schematic, the P992 does have the HV adjustment through potentiometer RV901 (code for variable resistor Tube Type 901).
It seems these monitors have the HV potentiometer adjustment option at RV901. Generally, CRT's work on similar principles, so there must be a HV adjustment somewhere.
So might it be just a question of tweaking this potentiometer (observing usual precautions)?
len
In the manual located here:
http://www.ablserv.com/files/windas/Wcats/Wincats_Manual.doc
the cable is mentioned. It ends in the 8-pin mini-DIN. I suppose one could make a cable like the one described earlier in this thread, substituting an 8-pin mini-DIN for the monitor end of things.
My best guess for the pinouts is listed at:
http://pinouts.ru/SerialPorts/sgi8_pinout.shtml
which is for an SGI serial port, but it may be completely wrong. If anyone tries it, please let us know how it goes!
All those labels end H or V. My guess is that being on the tube they all stand for "Vertical" and "Horizontal" nothing to do with brightness?
len
If you can find a G2 option, whether by a control signal or a modification of some kind, then it is the preferable way to go.
The master brightness control, if it can be found, is the way to go.
I was lucky with my Hitachi CM823F in that the brightness/screen G2 adjustment was integrated with the flyback transformer. I could remove the rastering easily, and likewise control the overall screen brightness.
The G2 voltage is generally in the order of 500-600 Volts, as opposed to the High Voltage Anode in the CRT being 25kV to 30kV. There is way more scope for tuning and control with the G2 than the HV.
To avoid the hassle you are having with the P992, it may be better just to buy another monitor for $50 to $100 with adjustments which are better known and more serviceable if needs be. Sorry if this is an uncool thing to say on this forum. :smiles:
Here are the diagrams. Judge for yourselves if its worthwhile.
By the way, I found a G500 service manual for the P1110 at:-
http://www.theusermanualsite.com
Registration is free of charge.
Compare and contrast the attached marked-up circuit diagrams. It appears the modified resistances must be lower than standard value to reduce brightness.
Please refer to other threads in this forum for information, Thanks.
P1110 Modification
P992 Modification
Thanks on behalf of us P992 owners.
So what order of Resistor do you think I should use to replace (or solder in parrallel with) R 941 ?
Thanks
Len (Eljay)
Thanks.
Does anyone know if this will work on the IBM P260 or is it different?
Thanks.
I just fixed two IBM P260's. One had a very bad green tint instead of black. The other had a bluish tint instead of black (although it was not that bad) and I added a 10-Megohm (1/4 watt) resistor in parallel to the other 10-Megohm resistor and it worked perfectly!
My brightness on one monitor is at 75/100 and on the other it is 49/100 and it looks great! Black is finally black again!
The one with the green tint still had a green tint over everything and I could not fix it through the menu, but I was able to fix it through the Nvidia Control Panel without much hassle.
Now both monitors look almost identical and also show very good greyscale performance after configuring.
They do seem a little on the dim side but I would much rather have good black levels and a bit dimmer picture.
Thanks to this awesome thread and people who like to experiment, I now have revived my old monitors for just one dollar and about 1 hour of time! Amazing!!
The p1110 and p992 marked-up circuit diagrams have been revised to make the similarities clearer.
The main similarity between these two diagrams is the voltage divider circuit outlined in green. This is likely to be important for G2 voltage regulation.
Before commiting any resistor changes, confirm the circuit diagram is correct and check the resistor with a multimeter for the correct resistance value.
For practical reasons, the parallel resistor modification is not recommended. The parallel resistors need to be very large and may not be readily obtainable. A 100M parallel resistor will give 18M.
The 22M high voltage resistor will need to be replaced with two high voltage resistors in series. If one of the resistors is 12M then the other resistor can be the same as the P1110 mod resistor (these are usually between 4M and 7M depending on the level of over-brightness being experienced).
The middle connection for the high voltage series resistors needs to be electrically isolated from the main board, to prevent short circuits. There is space on the board to properly place the resistors away from nearby circuitry as well.
The series resistors should be lightly soldered in place for testing purposes. The arrangement can be made permanent once the brightness problem is resolved.
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( http : // eric.hutzelman.com / articles / 1 - Sony - CRT - Brightness - Fix ...remove spaces... I totally understand the spam guards being in place, I'm simply paying respect to this person's article)
Will probably tweak a bit more, but it's looking great compared to what it was (super bright, scan lines...).
Simply unbelievable that this ol' thing can look mostly right again.
Went with two 2.2M Ohm, 1/2 watt resistors in series (4.4M Ohms total).
Probably going up to around 6M would be optimal, as others have mentioned. Will have to hunt down a good single resistor - I'd rather not have three in a row.
Still, they were worth the $1 from RadioShack (all they had in the Megaohms range were 1, 2.2, and 10...). ...Probably have to visit a local shop to get anything else...
Reprogramming these things sounds fun and all, but for me, soldering was a fun solution. Eventually, I think I might try the other route, but for now, this is just great that it works so well.
Still a fan of these monitors after all these years... Newer LCDs are finally starting to catch up to tube quality, but these things were probably some of the best monitors ever made.
Just wanted to thank everyone here for all the great posts on the subject of fixing these monitors. Made my day to land upon this monitor, find this thread, and then actually get this thing looking good!
You say the picture is perfect besides retrace lines? If the retrace lines were visible because of excessive G2 the picture would be un-bearable by anyone's standards.
This probably isn't the simple G2 adjustment. Neither will the cable be likely to help.
It's a know issue with the blanking hardware in the GDM-W900.
As some have been replacing resistors, you may need to replace some diodes and transistors on the A board with improved components.
D1806 DIODE 1SS376TE-17
D1807 DIODE 1SS376TE-17
D1808 DIODE 1SS376TE-17
Q1804 TRANS 2SA1162-G
Q1806 TRANS 2SK1849-TB
Q1807 TRANS 2SC2780-NK
Attached is a schematic of where these parts are located on the conductor side of the A board.
This information was from a Sony Service Bulletin, I haven't verified it on my own, but it sounds like you have the same issue.
If you buy the cable, could you describe what pins go where and how the cable is built. I realize this may be counter to your goal of selling the cable.
If you have the issue I described though, you'll need to open up the monitor anyway, and may as well just figure out where the pins go than buy the pricey cable.
Good luck either way.
The adjustments on the CRT yoke deal with convergence, purity/landing, and geometry. I wouldn't recommend changing them unless you know you need to.
Brightness is adjusted on the flyback, or on the board with the actual CRT socket. Assuming you mean G2 or screen grid voltage.
There are other tube factors that play into spot brightness, since it's a function of beam density,velocity, landing and phosphor efficiency.
Now, this isn't very helpful unless you know what factors control the above mentioned factors. I haven't found a lot of material about this. I did find a recent book about phosphors though, I'll have to request it at my library.
Did you follow the instructions exactly?
What's the file size and version of your RegDLL ? (88k.. I don't have a copy of winDas available to check if this is correct)You need the exact one mentioned in my installation instructions. No other will work.
Most Google links say this error is caused by a corrupt DLL or an incorrect version.
I've done this on XP sp2, so it's likely not an XP related issue.
Let me know if you figure out how to solve it.
What other threads?
Oh, and um, this is by far the most interesting post I've seen. I can't figure it out though.
Would you be so kind to give a more verbose explanation of how it works?
How did you know a P1110 is a G500?
How did you know what a P992 is, and thus find it's service manual?
So, with the FW90** series, even the HP, SUN, SGI branded models still say the GDM-FW9012 or whatever.
On the Dell, HP, Compaq P1110, P991, P992 etc. the sony GDM or CPD model number would still exist wouldn't it? How would I find it?
Just looking at where the hi voltage to the G2 is taped, I'd guess the voltage there is controlled by how much current passes through the other taps that lead to more complicated arrangements with amps and transistors, thus changing the voltage drop across those resistors.Or have I got that wrong?
What exactly do the amps and transistors do? I realize that a line from the CPU comes in with a signal, which some how varies what the amps and transistors sink from the G2 line.
Thanks for any help and explanation.
Thanks for that - I'm getting closer to a solution!
I ordered the cable but may try to cancel it now. Funnily enough, a photo of the A board appears in a post on p13 (I think) of this thread. Those components look terrifyingly small. When you say 'improved components' I'm not really sure what I should be looking for. I googled the serial numbers and I can find replacements with those numbers online. Should I just buy those?
Annoying that Sony's monitor helpline was unable to tell me that this was a known issue. Obviously they 'forgot' to update their database.
I read most of the pages in this thread and I would like to try the Windas approach to fix my Dell P1110 brightness issue. I have never done any soldering and I don't have any soldering kit. So, where can I get cheapest RS232<>TTL converter thing (just ready to use one)?
Thanks.
Yes, the list was of the improved components, I didn't list the originals. Infact, the service bulletin didn't either, I'd have to look into the parts list to see what they were.
Are the parts expensive? I'd imagine shipping would be most of the cost, but I haven't looked them up.
De-soldering and soldering small surface mount stuff is a pain.
Nice that you found a picture of the A-Board! I totally forgot about that. Poor guy who put it up never had his problem solved, as he couldn't get that cable or it's pin-out.
So... yeah.. um, I was hoping they were through hole components, too bad theiy're not.
I've done surface mount components only once before. I wish I would have had a magnifying glass, a sharper soldering iron point, and a good solder wick. Still managed to get this cap back on, no idea if I heat damaged it or not, at least I didn't create a solder short.
Then, how could you know you put it all back together the right way? Would turning it on with a botched 'repair' break more things?
With a cheap multimeter, it'd be pretty obvious whether or not you had the diodes back in and working correctly. There may be more ways to test the transistors, but at least you could confirm you didn't short anything.
If you have the multimeter, solder, flux, soldering iron and some time to check out transistors on Google, I think you'd have a good chance. The alternative being to put up with the retrace lines.
Heck, this might not even be your problem. I just brought it to your attention because I thought it sounded more like what you were describing.I'm just going by what you said and my questionable ability to match the symptoms. I don't want to recommend something I can't say for certain will fix it.
Eh, I'd just go for the cable from massmind. It's cheap and ready to use if you ask them for the Windas pin order (easy to switch yourself without tools). If you want support and don't mind paying a little extra, I'd go with Xweebie and Emusicraft.
If you want USB, some one else made a post about it. I've echoed it once I think, maybe on some other forum.
I have an updated version of the howto sitting on my hardrive... it's getting to be too late now to release it. The site traffic is going down. I still want to get all the circuits, the CRT, and the color stuff explained precisely. I may not finish it all in time.
If anyone knows any good books on this topic, let me know, as it's hard to find quality info on the web unless you're smart enough to work everything out from something as basic as Coulomb's law.
first i would like to let you know thta i think it AWESOME how you have dedicated time and helped many many many people fix there potentially beautiful monitors rather than throw them away because of the brightness problem , or other related issues that make the monitor unbarable
and i myself am another victim of the unbarable brightness issue with the dell p1110, i originally bought it used on ebay(stupid me didnt do any research about it tho) for a little over $100 w/shipping and thoguht it was just too good of a deal...until i got it and booted it up and discover the awful p1110 brightness issue(luckily the seller had a 7 day return warranty, so i told him about the issue and such and he refunded me for the monitor AND shippng AND told me not to even send it back, just keep it)
so now i got a free giant 21" monitor with the potential to make perfect looking again by spending about $10 bucks and doing a little researching online(as how i ended up here:P)
now i know there are 2 methods to go about this
either buy a 4-6 ohm r459 resistor and do a lil soldering
or buying the "rs232 to ttl 5v converter kit" and using the windas program to change the G2 voltage or something like that(and this is the method i am choosing to do since i REALLY dont want to pry open the monitor and solder and mess around with the insides of it)
now i was reading ur tutorial for thw windas method on ur geocities page, and trying to read a lot of that stuff really mind boggled me, and i have a to tight of schedule in my life right now to really learn the ins and outs about it(but obviously im going to push my self to learn the basic knowledge of it so i can atleast do it)
i was planning on buying the one kit thier selling on ebay(cant post a link cause im a new member) its the only one that shows up when u search "RS232 TTL 5V converter KIT", besides the windas program, is this all i need to do this, or are there extra cables i need to attain?
is it real complicated to set it all up? is there like any step by step guides that have pictures included, or step by step guides for dummies to do this? because a lot of the stuff in ur tutorial is way over my head
looking forward to a response from you, and thanks for all ur time
good day
http://cgi.ebay.com/MAX3232-RS232-to-TTL-module-converter-AVR-PIC-ARM_W0QQitemZ320242999787QQihZ011QQcategoryZ4661QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/TTL-To-RS232-Converter-Module_W0QQitemZ220227505380QQihZ012QQcategoryZ73128QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
or one of the other ones on ebay, but my question is, what the heck do i use to connect this contraption from my pc to my monitor, and where heck to get these cables/wires
and how do i know which specific pin on the adapter connects to what specific pin on the back of the monitor?
any answers would be MUCH appreciated
and im sorry if the answers to my question are lost somewhere on this thread, but this thread is so BIG lol
ill continue to read through this thread when i got some free time but if anyone can answer my questions, that would be GREAT
The attached schematic diagram illustrates the basic operating principle of the G2 grid voltage control circuit.
The G2 grid voltage is determined by the voltage drop occuring through the load resistor connecting the high voltage supply to the G2 grid.
The required G2 grid voltage is achieved by drawing a sufficient current through the load resistor from the high voltage supply.
The operational amplifier compares the G2 reference voltage to the G2 grid voltage sensed and it outputs a corrective voltage which controls the net sinking of current through the transistor and load resistor.
The critical aspects of the circuit for determining the G2 grid voltage, and hence screen brightness level, are as follows:
[1] The G2 reference voltage signal at the positive input to the operational amplifier must be stable and at the correct voltage level. This assumes the OSD control chip puts out the correct pulse-width-modulated G2 signal, and this signal is correctly rectified to the G2 reference voltage needed for the operational amplifier.
[2] The voltage divider resistors between the G2 grid and ground must have the correct resistance values.
[3] The high voltage supply must be greater than the desired G2 grid voltage.
[4] There should be no significant extraneous currents causing bias voltages in the voltage divider. For instance, the feedback current from the amplifier passes through the smaller dividing resistor on its way to ground. This causes a small bias voltage within the resistor which results in the G2 grid voltage being reduced by about 10 Volts or so.
The NON - CRITICAL aspects of the circuit for determining the G2 grid voltage, are as follows:
[5] The stability of the high voltage supply is not critical to the G2 grid voltage because the amplifier can compensate for the voltage variations, by controlling the current sunk through the load resistor.
[6] The change in performance characteristics of the power transistor with temperature or current is not critical because the amplifier can compensate for these variations too.
CONCLUSIONS
There are three ways to fix an overbrightness issue caused by excessive G2 grid voltage.
[1] Decrease the G2 reference Voltage signal appearing at the operational amplifier (Windas Method - Known)
[2] Decrease the "high voltage" resistor's resistance (Resistor Mod Version 1 - Known)
[3] Increase the "low voltage" resistor's resistance (Resistor Mod Version 2 - Not Known .... apparently)
This alternative resistor modification, could result in a potentiometer being used as a "screen brightness pot".
MEASURING G2 GRID VOLTAGE
There is a simple indirect method to estimate the G2 grid voltage.
Measure the G2 Reference Voltage, and multiply by the resistor ratio in the voltage divider.
Example. VG2 ref = 2.70 Volt, R1 = 100 KOhm, R2=20 MOhm
VG2 grid = 2.70 x 200 = 540 Volt.
I have the Dell P992 screen which is in exellent condition....other than the high brightness level ofcourse :rolleyes2
So now I see u guys have a resistor mod available, which I'm certainly willing to undertake, though what I would very much appreciate is a picture of the board and the highlighted resister as seen on http://eric.hutzelman.com/articles/1-Sony-CRT-Brightness-Fix website. This would make me feel alot more confidant seeing exactly where i should be on the board and such.
If successful I also have another screen to do as I recommended my young cousin to buy one not too long ago..
These screens are just too good not to be used, and a big thankyou to all who have contributed here so far, well done guys :cheers3:
My second monitor is a P1130. The problem with that one isn't the picture, as it is ACE!!! But, the monitor emanates this quite toxic smell from the core of the tube. What to do??? The monitor is not overly hot, and the smell is comming out at a constant rate and can be perceived as discrete but with my windows closed in the room, it can get too polluted with this hazy smell.
Thanks for any help.
<O:p</O:p
I own a Sony CPD-G420 monitor. I need to be able to adjust the convergence of the red & blue signals INDIVIDUALLY. As you may know, the OSD controls on the front of this monitor allow you to adjust the red & blue signals SIMULTANEOUSLY. That is, as you change the value in the OSD, the blue & red beams move towards or away from each other. There is a horizontal control and a vertical control. Unfortunately the points where the blue & red meet do NOT coincide with the green beam (either horizontally or vertically). It's very close, but I still detect the slight fringe on text & fine lines. This small error is consistent across the whole display.<O:p</O:p
<O:p</O:p
Before I invest the time & money in getting the RS232 – TTL cable & setting up the WinDAS software, I hoped to confirm that this INDIVIDUAL adjustment of the red & blue convergence will be possible on a Sony G420 monitor. From some comments in the thread, there seemed to be some Sony models that might not support this in WinDAS. Has anyone done this individual convergence adjustment on a G420, or knows for sure that it is possible via the software? Or am I destined to have to deal with mechanical & magnetic adjustments inside the monitor? Thank you very much for your input.<O:p</O:p
<O:p</O:p
The colors of the Sony monitor are gorgeous, but I think I’ve been spoiled by the perfect convergence on my ageing .25mm dot Nanao monitor. That’s making me want to get it right on the Sony as well, if possible, as I also work a lot with text.