Don't think you asked about location... it might just happen that i live on the other side of the world and shipping would be thru the roof. I live in Bucharest, Romania.
Don't think you asked about location... it might just happen that i live on the other side of the world and shipping would be thru the roof. I live in Bucharest, Romania.
Oh. Nevermind then. It's hard to find a p1110 for cheap in the U.S.
I have just opened up the monitor. I'm in the process of removing the metal shields.
OK. I haven't removed any serious stuff as I don't want to forget where all the screws go and how the shields go back on. Here is a picture of the monitor:
My P1130 has two problems (aside from the "image too bright and green before the monitor warms up") - sometimes (a very rare event, something like once in two months of everyday use) the screen blinks bright blue and then the image becomes yellow (like the color temperature was set to "low") for a few minutes. Probably some bad connection (or a short) somewhere, but I have no way of finding it (since it is so rare and I would have to look for it with the monitor turned on). Another problem is that if it is colder in the room then the monitor takes about a minute to warm up and show picture. On the other hand, if the room temperature is 36 degrees C, the monitor displays picture almost immediately.
Anyone has the same problem or knows what can be wrong with the monitor?
The monitor used to be too bright and have a green image, but I reduced the brightness with WinDAS and corrected the color using the on-screen menu. WinDAS has a way of adjusting the color more precisely, but that requires a colorimeter which I do not have.
Been through this. Not sure if it's on here but you need the service dongle which requires a picture to where each pin goes and where the connectors are. There is a service port on the back under a little rectangle punchout. It plugs into your computer and you use software to adjust the internal monitor. Once you have all that in place you can adjust the color, hue, brightness and pretty much everything. I have two of these and had to do this 4 years ago. If I can find the documentation I'll come back an post it. I still have the two monitors as well as the dongle but giving them away now. I have all LCD and LED, but both monitors rock for color and contrast. Nothing wrong with them, just big.
the screen blinks bright blue and then the image becomes yellow (like the color temperature was set to "low") for a few minutes. Probably some bad connection (or a short) somewhere,
Internal short in tube. Fixable but risky... since it happens so rarely i'd let it be.
Another problem is that if it is colder in the room then the monitor takes about a minute to warm up and show picture. On the other hand, if the room temperature is 36 degrees C, the monitor displays picture almost immediately
See if the tube starts glowing as soon as you turn it on (with signal input of course). If it takes a while to light up, resolder the heater connections on the back of the neck board.
Interestingly enough, your monitor seems to NOT have the drift correct circuit... but i'd look for it, since the symptoms are exactly the same as my P1110.
@ sintz: That's what we've been doing all this while.
As a owner and a CRT enthusiast, it’s very interesting to see this 12-year old monitor and its problems are still discussed here regularly. As Sony has never officially admitted any design flaws in this model, these technical issues may remain mystery forever, but I have always tried to find the truth. There are several typical problems with this monitor:
1. Abnormal G2 voltage, usually 100V~ higher than its original spec at 522V. The G2 voltage can be bring down by modifying relevant value with WINDAS, and after the tweaking, overall brightness level can indeed be lowered. The cause of this phenomenon is still unclear – some people believe it’s caused by EEPROM data corruption, which I seriously doubt: data corruption in ROM is usually random, so why it’s always the G2 value suffer the loss? 2. The picture is over-bright, a little greenish on black at startup and after a while (15-20 minutes or so) the picture become darker, its color more saturated and able to maintain correct black & white balance. Some people claim that brings down G2 back to normal will cure everything, but it’s not true. Although after proper adjustment (for my unit, the G2 value was tweaked from 157 to 126, set at 30 in OSD for brightness) the monitor’s brightness level may be in normal range even the moment after a cold start, but the tendency (darker and deeper over time) is still the same, while the G2 is actually stable all the time. I think this is caused by some inferior semiconductor component, IC403 or IC406 perhaps, the characteristic of which will drift as temperature arises. Since I don’t have any replacement parts, I cannot confirm. 3. No picture, filament will not be light up after power button is pushed. This is often caused by a faulty BA00AST IC, which is an adjustable linear voltage regulator similar to 7805 and provides power for the heater.
By the way, P1110 (G500, and even FW900) lacks the mighty GEM (Graphic Enhance Mode) button featured in earlier Sony computer monitors like 220GS/D1025TM, which limits its effectiveness in movie playback / gaming. The button is replaced by an Auto-Center button, which is almost useless as everyone knows. Sony engineers are not fools, so I guess there must be technical difficulties behind this change. Despite all these problems, P1110 is still a decent monitor, although it’s far from perfect.
1. Abnormal G2 voltage, usually 100V~ higher than its original spec at 522V. The G2 voltage can be bring down by modifying relevant value with WINDAS, and after the tweaking, overall brightness level can indeed be lowered. The cause of this phenomenon is still unclear – some people believe it’s caused by EEPROM data corruption, which I seriously doubt: data corruption in ROM is usually random, so why it’s always the G2 value suffer the loss?
That bugs me too. But what doesn't seem right to me is that although the G2 voltage is controlled by PWM from the micro, there is no feedback back to it! So the G2 adjustment in WinDAS is just a plain dumb hardcoded value, you set it and it affects the G2 voltage directly, but the MCU has no idea what the G2 voltage actually is! Which begs the question, why let the MCU decide the value? Wouldn't it have been easier for everyone to just use a plain old pot for G2 control, like everyone else did?
As for why it increases over time, i think it's a firmware bug not EEPROM corruption.
And thanks for mentioning the "proper" G2 value, i hadn't known it until now. If it's mentioned in the service manual i'd like you to point me to it, coz i didn't find it. With all adjustments complete i've arrived at somewhere around this value too for mine, so clearly i must be doing right.
2. The picture is over-bright, a little greenish on black at startup and after a while (15-20 minutes or so) the picture become darker, its color more saturated and able to maintain correct black & white balance. Some people claim that brings down G2 back to normal will cure everything, but it’s not true. Although after proper adjustment (for my unit, the G2 value was tweaked from 157 to 126, set at 30 in OSD for brightness) the monitor’s brightness level may be in normal range even the moment after a cold start, but the tendency (darker and deeper over time) is still the same, while the G2 is actually stable all the time.
I found a fix for that by disabling the "drift correct" circuit, see above. It still takes around 10 minutes to fully warm up, but it's tons better than it was before. Mine used to take 2 hours to settle! And it required a lower than normal G2 voltage (430v) for proper brightness range, even when it did settle down.
Hello guys, I own a Formac ProNitron 21/750 (same model as dell P1110 - chassis GDM5403) After several tweaks with win das past years, it seems to be quite stable, and really crystal clear. I'm very interested by Th3_uN1Qu3 mods on IC406 : maybe i could try to bypass the transistor which causes problems.
I have had another problem with this monitor last year, which was fixed :
The brightness was not stable, and i was wondering if the monitor was ready to go to the trash...
But, in fact, the solution was very simple : after resoldered all the connections beetween N-board and D-board, it was OK.
I suspect many problems could be fixed by carrefully resolder all the connections.
I think i'll be cutting the G2 control line from the micro and just plop a multiturn pot in there and call it a day. I'll never have to use WinDAS again!
I'll also point out that all of the resistor mods people have done until now are wrong - because they have addressed the effect not the cause. Those resistors all checked fine on my P1110 which came with a really bad case of overbrightness (so clearly, they do not need to be replaced), and by changing the resistors in the divider for the opamp feedback loop the G2 voltage will still be prone to drifting over time because it's still wired to the MCU. Now, if you cut the MCU line and place a multiturn pot instead, you have addressed the cause and it will never drift again regardless of what the MCU is trying to do. I'll elaborate on that once i perform the mod on my own P1110.
IMO, the circuitry in these monitors is far too complicated, they could have done it a lot easier. Because fact is, the tube is still going to age and require alignment every few years - all they did was make it harder to adjust. Like the stupid "lowering contrast when increasing brightness past 50" thing. I want my trimpots back damn it! If i have the time i'll be rolling my own MCU to take care of the critical functions. It won't be easy but it's doable. I suspect that some of these mods can be done at firmware level and patched in via WinDAS, but with no datasheet on the original micro this wouldn't be easy. Rolling my own seems like a far better idea. In fact, if it were me, i'd just replace the whole thing by a bunch of trimpots, but not everyone likes the idea of getting inside their monitor all the time.
Hello, Th3_uN1Qu3, if you made such a mod, please post the schematics : i'm also very interested by replacing those silly circuits by a single pot. IMO, they wanted to make a monitor which is immediately usable when switching ON, by placing complex circuits for controlling brightness. In the old times, i've had monitors which tends to be very dark when switching on, and takes 10~20 minutes to warm up. With the P1110, it's the opposite.
Well that's easy enough. If the original circuit looked like this:
Then the mod would be like this:
Note that any value between 1k and 500k will work for the trimpot - i just happen to have a ton of 100k ones lying around. The higher values also are more prone to interference, so i'd stick to 100k or under. It is not necessary to actually remove the deleted parts from the board, just find a way to cut the trace leading to the opamp and drop your trimpot on there.
What i do not know yet is whether the G2 value set by the MCU affects others too, like contrast or colors. Well, only one way to find out i guess. I'll be performing the mod tomorrow. However, i want to take it one step further. As you see, the G2 voltage is controlled by an opamp. That gives extraordinary flexibility to the adjustment - you can control it by basically anything. Now, i'm about to blow your socks off. Tube takes time to heat, correct? Brightness drifts until tube temperature settles. G2 voltage directly affects brightness. Now, what if we put a temperature sensor on the tube neck, and use that to transparently adjust G2, thus eliminating the brightness drift entirely? Of course, a trimpot will still be there to set the base level, but the temperature sensor should be able to keep things in check once the base level is correct. Now it's time to stick a temperature probe to the tube neck and do some data logging.
Indeed, that's very simple and much more easier than connecting the RS232 wire and using DAS... I'm curious to know the result. And, like you said, I hope the MCU does not control other parameters (contrast ? white balance ?)
The MCU does control those other parameters (since they're in the menu it's obvious that the MCU controls them), i just hope it doesn't take the G2 value into account when adjusting them.
Hang on, there's some cool data coming up.
Edit: Here we go. I plotted tube temperature vs time, measurements taken every minute. The probe was stuck on the top of the neck, right under the first metal ring, the one that holds the purity magnets in place. Ambient temperature was 22C. As you can see, past 15 minutes the temperature rise slowed down, and it stopped rising entirely past 30 minutes. Visual feedback confirmed that, after 15 minutes the brightness drift per minute became unnoticeable, and past 30 minutes the picture is completely stable.
Of course the temperatures are relative, if the ambient temp were different the tube temp would be different too, but this proves that with the drift correct circuit removed, brightness drift is due to the tube and not any other component. It also shows why the drift correct circuit didn't work: Tube temperature vs time is nonlinear, whereas that transistor, not being in contact with the tube directly, provided a linear thermal compensation, which isn't what we need.
As far as i know G2 voltage vs black level is a linear relationship, provided we stay out of cutoff/saturation. Since the tube worked just fine with G2 a whole hundred volts lower than nominal before removing the drift correct circuit (that messed with the cathode voltages), and that hundred volts meant a significant change in brightness (from "barely visible" to "normal") we have a decent range to play with. By making G2 voltage a function of tube temperature i believe we can eliminate brightness drift completely, reducing the "warmup time" from 15-20 minutes to 2 minutes or less.
Time to stick a thermistor on the tube neck and see what happens.
But maybe there's another component around the tube which reacts to the tube warming ? Especially some of the big transistors on the D-board, just near the tube.
Two years ago, I covered almost all the vents with paper and tape so that the temperature inside the housing is higher. Especially in the winter because my house is not warm enough...
That worked : black on screen becomes really pure black, with this trick. But just for a time... after that i decided to use win das.
Also, you may have noticed that the black level is very deep when the image which was displayed just before was very bright. But if we display a dark image (a screen saver, for example), after a few minutes, the black drift back to dark gray. It seems that some component (maybe the tube ?) cools when displaying a dark image, and warms when displaying a bright one.
I believe the "drift control" circuit is responsible of what you are seeing with the black level drifting back towards grey when displaying a dark image. Mine doesn't do that.
Once it's warmed up, as long as the heater remains on the tube temperature remains constant, regardless of the brightness level of the picture, so you can take the tube out of this equation. Bypass the drift control transistor and see what that gives you.
I've done a bit of math and it turns out we can get pretty good precision from simple cheap NTC thermistors over a temperature range of +/-25C, using a parallel precision resistor to linearize the NTC. This should be enough for the typical operating range of the tube, and will allow for a warmup time of 5 minutes, maybe even shorter. Now all that needs to be done is some measurements to determine the actual values needed for the circuit.
Anyway, the circuit is so simple i can hardly believe nobody's done it before (searching for "cathode ray tube thermal compensation" brings up a few patents about projectors, two about CRT mask design, but nothing like i described above). I suspect however that the severity of this brightness drift varies with the age of the tube (since it didn't do it when it was brand new) so it's likely an adjustment that will need to be touched up once an year or so. More trimpots for you!
Internal short in tube. Fixable but risky... since it happens so rarely i'd let it be.
Thanks for the information. This saves me many hours of trying to find a bad connection on one of the boards. I just hope that short does not become worse and does not take out any electronics.
See if the tube starts glowing as soon as you turn it on (with signal input of course). If it takes a while to light up, resolder the heater connections on the back of the neck board.
OK, I'll look and if it is as you say, I'll try resoldering the connections the next time I move the monitor. If it is as you say (bad heater connection), can this cause damage to the tube if the heaters take a while to light up?
Interestingly enough, your monitor seems to NOT have the drift correct circuit... but i'd look for it, since the symptoms are exactly the same as my P1110.
I thought I was just imagining that. Maybe it's located somewhere else. Right now I don't have time to look. I'll have time during the weekend.
Well, Th3_uN1Qu3, I have the official schematic diagram with reference voltage of Sony G500 monitor (identical to P1110/IBM260/SUN5410 etc, known internally as G1 chassis.) And if you like, just tell me, I can e-mail it to you)
BTW, IMHO P1130s (SONY G520, CR1 chassis) is also imperfect, although they indeed eliminates the over-brightness problem. Due to cost-down, these machines are generally made of inferior components compared to earlier models. To list some of its typical problems:
1. Incorrect color balance. Although not all units suffer from this, but at least 6 out of 10 used P1130s have the problem of inaccurate color, albeit severity varies. As you know, inaccurate color is lethal to a pro-grade monitor. 2. In some units, weird random patterns may appear at startup (for example, irregular purple bar and triangle.) and normally will return to normal after twenty seconds or so. It looks like a digital circuit failure, the symptom just like a faulty graphic card would do). I guess the source of the trouble is the “input select IC”, because which is the only digital part in the RGB signal’s path. 3. Some units may randomly switch to INPUT2 without being prompted, causing a blank-screen and back to normal automatically after a few seconds. It is annoying, and the switch itself is actually in perfect condition. I believe it’s caused by the unstable “input select IC”. 4. P1130 lacks a manual convergence control; therefore its convergence is usually worse than P1110s. 5. Still lacks one-button brightness-enhancement button.
Overall, when it comes to FD-CRT computer monitors, I think Mitsubishi Diamondtron M2 units are more successful than their Sony counterparts. Mitsubishis are very stable, even more transparent than Sony tubes, comes with a very effective super-bright button, and to this day I haven’t found any design flaws for these units.
Overall, when it comes to FD-CRT computer monitors, I think Mitsubishi Diamondtron M2 units are more successful than their Sony counterparts. Mitsubishis are very stable, even more transparent than Sony tubes, comes with a very effective super-bright button, and to this day I haven’t found any design flaws for these units.
My dad has one of those. They are awesome! It is branded as NEC but when you pull up the OSD it says Mitsubishi.
P1130 lacks a manual convergence control; therefore its convergence is usually worse than P1110s.
You mean the one in the menu? My P1130 has it. I still needed to tweak the ones on the side of the deflection coil for best picture - the XCV control was most helpful on both P1130 and P1110.
No. I didn't mean the convergence OSD setting. I mean the mechanical adjustments for convergence near the tube, and if I remembered correctly, P1130s haven't installed such device by default and its convergence is fully digital controlled and is supposed to be adjustable via DAS only. Maybe P1130 sets exported to your country is different from what we've used here, though.
Besides, both P1110 and P1130 should use the same type of tube. So if you want to prove that the tube itself is causing P1110s need so much time to "warmup", you can try switching the boards of these.
Overall, when it comes to FD-CRT computer monitors, I think Mitsubishi Diamondtron M2 units are more successful than their Sony counterparts. Mitsubishis are very stable, even more transparent than Sony tubes, comes with a very effective super-bright button, and to this day I haven’t found any design flaws for these units.
I own each of these monitors, and for me the image of Diamondtron suffers from a fatal flaw: the gamma of the image is poorly set and not linear at all. Almost impossible to calibrate correctly. They can be used for office or games, but certainly not for graphics applications such as image editing. Of course on these monitors, the tube warm up quickly. But I prefer the trinitron which has a far better picture.
There is a reason why Sony eliminated the pots inside their monitor.
1. Most people don't like to wear rubber gloves against electric shocks all the time when they need to adjust a monitors.
2. WinDAS would allow general quick software fixes when all monitors would have suffered from the same misadjustment during warranty time (unfortunately Sony seems to ignore what happens after).
3. (MOST IMPORTANT) Circuit temperature drifts differently when the case is closed, so you would need to do fine tuning with closed case (or open and close it every few minutes) which can be really awkward. With my Nokia 417TV (videophile CRT TV) I have installed additional multi-thread colour trimmers accessible through tiny holes at the right case side to tweak the tv colours in real life operation (warmed up with case closed)
No. I didn't mean the convergence OSD setting. I mean the mechanical adjustments for convergence near the tube, and if I remembered correctly, P1130s haven't installed such device by default and its convergence is fully digital controlled and is supposed to be adjustable via DAS only. Maybe P1130 sets exported to your country is different from what we've used here, though.
Besides, both P1110 and P1130 should use the same type of tube. So if you want to prove that the tube itself is causing P1110s need so much time to "warmup", you can try switching the boards of these.
In the CRT FAQ the mention that late Trinitron tubes convergence and purity was adjusted in factory by magnetizing parts inside (or on the back?) of the tube in special ways, and they warn never to degauss such CRTs with a too strong external coil or from the back because this can erase the magnetic adjustment and make them unusable.
I am still musing where the "colour return" data is stored (not in the WinDAS file) and what it changes. May it be something magnetic???
Comments
I have just opened up the monitor. I'm in the process of removing the metal shields.
http://www.mojoimage.com/free-image-hosting-view-09.php?id=6767IMG_20120126_180600.jpg
Another problem is that if it is colder in the room then the monitor takes about a minute to warm up and show picture. On the other hand, if the room temperature is 36 degrees C, the monitor displays picture almost immediately.
Anyone has the same problem or knows what can be wrong with the monitor?
The monitor used to be too bright and have a green image, but I reduced the brightness with WinDAS and corrected the color using the on-screen menu. WinDAS has a way of adjusting the color more precisely, but that requires a colorimeter which I do not have.
@ theothernewguy:
http://www.eserviceinfo.com/downloadsm/3282/Sony_CPD-4402.html
http://www.eserviceinfo.com/downloadsm/3283/Sony_CPD-4402.html
http://www.eserviceinfo.com/downloadsm/3284/Sony_CPD-4402.html
Interestingly enough, your monitor seems to NOT have the drift correct circuit... but i'd look for it, since the symptoms are exactly the same as my P1110.
@ sintz: That's what we've been doing all this while.
1. Abnormal G2 voltage, usually 100V~ higher than its original spec at 522V. The G2 voltage can be bring down by modifying relevant value with WINDAS, and after the tweaking, overall brightness level can indeed be lowered. The cause of this phenomenon is still unclear – some people believe it’s caused by EEPROM data corruption, which I seriously doubt: data corruption in ROM is usually random, so why it’s always the G2 value suffer the loss?
2. The picture is over-bright, a little greenish on black at startup and after a while (15-20 minutes or so) the picture become darker, its color more saturated and able to maintain correct black & white balance. Some people claim that brings down G2 back to normal will cure everything, but it’s not true. Although after proper adjustment (for my unit, the G2 value was tweaked from 157 to 126, set at 30 in OSD for brightness) the monitor’s brightness level may be in normal range even the moment after a cold start, but the tendency (darker and deeper over time) is still the same, while the G2 is actually stable all the time. I think this is caused by some inferior semiconductor component, IC403 or IC406 perhaps, the characteristic of which will drift as temperature arises. Since I don’t have any replacement parts, I cannot confirm.
3. No picture, filament will not be light up after power button is pushed. This is often caused by a faulty BA00AST IC, which is an adjustable linear voltage regulator similar to 7805 and provides power for the heater.
By the way, P1110 (G500, and even FW900) lacks the mighty GEM (Graphic Enhance Mode) button featured in earlier Sony computer monitors like 220GS/D1025TM, which limits its effectiveness in movie playback / gaming. The button is replaced by an Auto-Center button, which is almost useless as everyone knows. Sony engineers are not fools, so I guess there must be technical difficulties behind this change. Despite all these problems, P1110 is still a decent monitor, although it’s far from perfect.
As for why it increases over time, i think it's a firmware bug not EEPROM corruption.
And thanks for mentioning the "proper" G2 value, i hadn't known it until now. If it's mentioned in the service manual i'd like you to point me to it, coz i didn't find it. With all adjustments complete i've arrived at somewhere around this value too for mine, so clearly i must be doing right.
I own a Formac ProNitron 21/750 (same model as dell P1110 - chassis GDM5403)
After several tweaks with win das past years, it seems to be quite stable, and really crystal clear.
I'm very interested by Th3_uN1Qu3 mods on IC406 : maybe i could try to bypass the transistor which causes problems.
I have had another problem with this monitor last year, which was fixed :
The brightness was not stable, and i was wondering if the monitor was ready to go to the trash...
But, in fact, the solution was very simple :
after resoldered all the connections beetween N-board and D-board, it was OK.
I suspect many problems could be fixed by carrefully resolder all the connections.
I'll also point out that all of the resistor mods people have done until now are wrong - because they have addressed the effect not the cause. Those resistors all checked fine on my P1110 which came with a really bad case of overbrightness (so clearly, they do not need to be replaced), and by changing the resistors in the divider for the opamp feedback loop the G2 voltage will still be prone to drifting over time because it's still wired to the MCU. Now, if you cut the MCU line and place a multiturn pot instead, you have addressed the cause and it will never drift again regardless of what the MCU is trying to do. I'll elaborate on that once i perform the mod on my own P1110.
IMO, the circuitry in these monitors is far too complicated, they could have done it a lot easier. Because fact is, the tube is still going to age and require alignment every few years - all they did was make it harder to adjust. Like the stupid "lowering contrast when increasing brightness past 50" thing. I want my trimpots back damn it! If i have the time i'll be rolling my own MCU to take care of the critical functions. It won't be easy but it's doable. I suspect that some of these mods can be done at firmware level and patched in via WinDAS, but with no datasheet on the original micro this wouldn't be easy. Rolling my own seems like a far better idea. In fact, if it were me, i'd just replace the whole thing by a bunch of trimpots, but not everyone likes the idea of getting inside their monitor all the time.
IMO, they wanted to make a monitor which is immediately usable when switching ON, by placing complex circuits for controlling brightness.
In the old times, i've had monitors which tends to be very dark when switching on, and takes 10~20 minutes to warm up.
With the P1110, it's the opposite.
Then the mod would be like this:
Note that any value between 1k and 500k will work for the trimpot - i just happen to have a ton of 100k ones lying around. The higher values also are more prone to interference, so i'd stick to 100k or under. It is not necessary to actually remove the deleted parts from the board, just find a way to cut the trace leading to the opamp and drop your trimpot on there.
What i do not know yet is whether the G2 value set by the MCU affects others too, like contrast or colors. Well, only one way to find out i guess.
I'm curious to know the result.
And, like you said, I hope the MCU does not control other parameters (contrast ? white balance ?)
Hang on, there's some cool data coming up.
Edit: Here we go. I plotted tube temperature vs time, measurements taken every minute. The probe was stuck on the top of the neck, right under the first metal ring, the one that holds the purity magnets in place. Ambient temperature was 22C. As you can see, past 15 minutes the temperature rise slowed down, and it stopped rising entirely past 30 minutes. Visual feedback confirmed that, after 15 minutes the brightness drift per minute became unnoticeable, and past 30 minutes the picture is completely stable.
Of course the temperatures are relative, if the ambient temp were different the tube temp would be different too, but this proves that with the drift correct circuit removed, brightness drift is due to the tube and not any other component. It also shows why the drift correct circuit didn't work: Tube temperature vs time is nonlinear, whereas that transistor, not being in contact with the tube directly, provided a linear thermal compensation, which isn't what we need.
As far as i know G2 voltage vs black level is a linear relationship, provided we stay out of cutoff/saturation. Since the tube worked just fine with G2 a whole hundred volts lower than nominal before removing the drift correct circuit (that messed with the cathode voltages), and that hundred volts meant a significant change in brightness (from "barely visible" to "normal") we have a decent range to play with. By making G2 voltage a function of tube temperature i believe we can eliminate brightness drift completely, reducing the "warmup time" from 15-20 minutes to 2 minutes or less.
Time to stick a thermistor on the tube neck and see what happens.
Especially some of the big transistors on the D-board, just near the tube.
Two years ago, I covered almost all the vents with paper and tape so that the temperature inside the housing is higher. Especially in the winter because my house is not warm enough...
That worked : black on screen becomes really pure black, with this trick.
But just for a time... after that i decided to use win das.
But if we display a dark image (a screen saver, for example), after a few minutes, the black drift back to dark gray.
It seems that some component (maybe the tube ?) cools when displaying a dark image, and warms when displaying a bright one.
Once it's warmed up, as long as the heater remains on the tube temperature remains constant, regardless of the brightness level of the picture, so you can take the tube out of this equation. Bypass the drift control transistor and see what that gives you.
I've done a bit of math and it turns out we can get pretty good precision from simple cheap NTC thermistors over a temperature range of +/-25C, using a parallel precision resistor to linearize the NTC. This should be enough for the typical operating range of the tube, and will allow for a warmup time of 5 minutes, maybe even shorter. Now all that needs to be done is some measurements to determine the actual values needed for the circuit.
Anyway, the circuit is so simple i can hardly believe nobody's done it before (searching for "cathode ray tube thermal compensation" brings up a few patents about projectors, two about CRT mask design, but nothing like i described above). I suspect however that the severity of this brightness drift varies with the age of the tube (since it didn't do it when it was brand new) so it's likely an adjustment that will need to be touched up once an year or so. More trimpots for you!
If it is as you say (bad heater connection), can this cause damage to the tube if the heaters take a while to light up?
BTW, IMHO P1130s (SONY G520, CR1 chassis) is also imperfect, although they indeed eliminates the over-brightness problem. Due to cost-down, these machines are generally made of inferior components compared to earlier models. To list some of its typical problems:
1. Incorrect color balance. Although not all units suffer from this, but at least 6 out of 10 used P1130s have the problem of inaccurate color, albeit severity varies. As you know, inaccurate color is lethal to a pro-grade monitor.
2. In some units, weird random patterns may appear at startup (for example, irregular purple bar and triangle.) and normally will return to normal after twenty seconds or so. It looks like a digital circuit failure, the symptom just like a faulty graphic card would do). I guess the source of the trouble is the “input select IC”, because which is the only digital part in the RGB signal’s path.
3. Some units may randomly switch to INPUT2 without being prompted, causing a blank-screen and back to normal automatically after a few seconds. It is annoying, and the switch itself is actually in perfect condition. I believe it’s caused by the unstable “input select IC”.
4. P1130 lacks a manual convergence control; therefore its convergence is usually worse than P1110s.
5. Still lacks one-button brightness-enhancement button.
Overall, when it comes to FD-CRT computer monitors, I think Mitsubishi Diamondtron M2 units are more successful than their Sony counterparts. Mitsubishis are very stable, even more transparent than Sony tubes, comes with a very effective super-bright button, and to this day I haven’t found any design flaws for these units.
Besides, both P1110 and P1130 should use the same type of tube. So if you want to prove that the tube itself is causing P1110s need so much time to "warmup", you can try switching the boards of these.
Almost impossible to calibrate correctly.
They can be used for office or games, but certainly not for graphics applications such as image editing.
Of course on these monitors, the tube warm up quickly.
But I prefer the trinitron which has a far better picture.
1. Most people don't like to wear rubber gloves against electric shocks all the time when they need to adjust a monitors.
2. WinDAS would allow general quick software fixes when all monitors would have suffered from the same misadjustment during warranty time (unfortunately Sony seems to ignore what happens after).
3. (MOST IMPORTANT) Circuit temperature drifts differently when the case is closed, so you would need to do fine tuning with closed case (or open and close it every few minutes) which can be really awkward. With my Nokia 417TV (videophile CRT TV) I have installed additional multi-thread colour trimmers accessible through tiny holes at the right case side to tweak the tv colours in real life operation (warmed up with case closed)
I am still musing where the "colour return" data is stored (not in the WinDAS file) and what it changes. May it be something magnetic???