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.
1. The focus/screen pots are plastic on all of them, so this one falls. They coulda let us have a screen (G2) pot at least. And the focus pots are still there. And you can do them by hand without getting a shock. Generally, all the control voltages pots may tweak are very low (and all the voltages WinDAS has access too are certainly very low too, or the OSD chip would blow up), so touching the pots would not give an electric shock.
2. True. Too bad the warranty period has expired like 10 years ago.
3. Never had this one happen... when it's warmed up, it's warmed up, and all the adjustments done in the warmed up state will be the same the next time you turn it on and let it warm up. If thermal drift is so significant then there's something else wrong with it.
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 think this only applies to TV tubes. So far, all Trinitron monitors i've taken apart use the completely conventional approach to purity and convergence. Magnets on the tube neck and a dynamic convergence assembly on the side of the deflection coil.
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???
No wai, magnetic core memory was popular in the late 50s, but i can't see it being used now. Are you really sure the data isn't in the WinDAS file? Then there must be a separate area of the EEPROM which contains those settings. The EEPROM can be read/written using a programmer or another microcontroller. The existence of a separate area gives some answers, such as why disabling the "lowering contrast when increasing brightness past 50" option only lasts until you turn the thing off, and then it resets to doing it again.
I have compared the WinDAS output files from my monitor before and after doing "colour return" and not values changed, despite the measured red saturation curve differed (it is still somewhat oversaturated (may be that bypassing "drift correct" and setting G2 back to the initial value might fix that).
With magnetic storage I didn't mean "core" memory, but that coils magnetize parts of the CRT somehow to change the linearity and levels of RGB gun outputs or such crazy stuff (e.g. by deflecting a part of the beam against a shield grid or what ever). Yes, that sounds overly complicated to be reasonable, but the CRT FAQ hint about modern Trinitron tubes suggested that such nasty hidden secrets may exist (perhaps invented to confuse competitors to complicate reverse engineering - remember the PlayStation 3 copy protection...).
But perhaps the calculated "colour return" correction data is simply directly output into a write-only memory (e.g. inside the RGB amp IC for faster access) where it can't be read back by WinDAS. I remember that in 1990th there were analogue audio sampling ICs (Hallmark Romcorder) to reduce chip size compared to conventional digital memory. Now think of what happens when the charge level inside such an analogue EEPROM(?) fades away over time. This could be well a reason for overbright picture or wrong colour curves.
Again, not feasible. The color return settings are likely stored in another area of the EEPROM, which is not accessible via WinDAS. All other behavior is simply due to the aging of the tube. When they implemented the color return function, i doubt they had a 10 year old tube to try it on.
Hello, I have another question regarding those monitors : Does anyone knows if there's a way to increase the sharpness ? Of course, we assume that it is perfectly adjusted with the two pots on the FBT.
I ask this because my two P1130 are not exactly as sharp as my P1110, although they all are well adjusted. They are a little "softer", compared to my old one. (Of course this is not about geometry or convergence, which are well adjusted in all cases)
Short of decreasing the refresh rate, there is no way. Here it's the other way round - the P1130 is sharper. It's simply due to the number of power-on hours each tube has.
Short of decreasing the refresh rate, there is no way. Here it's the other way round - the P1130 is sharper. It's simply due to the number of power-on hours each tube has.
Hm... I don't agree with this : all the P1130 I have seen are less sharp than my P1110, which has an huge amount of hours of usage. Maybe it's related to certain tubes better than others ? (of the same type, of course)
It has to do with many things. Optimum focus point also drifts with time - you haven't gotten the chance to tweak those P1130s you've seen did you. Sure, you could simply be lucky, but until you've had one of each side by side tweaked to their fullest you can't say for sure.
I agree with pecos. The issue that pecos pointed out (not-as-sharp, if blurred, detail, e.g. text) is not a sharpness problem but because most P1130 lacks manual convergence control assembly near the neck, as I mentioned before. I have seen many P1130 sets, including brand-new ones, and in almost all cases P1110 beats P1130 in terms of convergence. So it’s definitely not tube-condition related. Thus, I guess what Th3_Un1qu3 got is probably either an engineering sample/ early production batch or one modified by a reseller (using such convergence device or even the whole tube assembly from a P1110). Th3_Un1qu3, please tell me the date/place of manufacture of your p1130 set, which is printed on its back. BTW, the “perfect” Trinitron computer monitor I ever used is neither a P1110 nor a P1130, but a ’99 17in V. Flat DELL D1025TM (CPD-200GS equivalent). After 12 years of daily usage, that machine is still extremely good in term of color balance / brightness / focus / convergence and never required any adjustment! BTW, what is a Formac? I saw this name in windas but have no idea about this brand at all... maybe "For Apple Mac"?
Hello, cctv_1234, Formac Elektronik GmbH is a European based manufacturer of various PC devices. In the 90', they sold only peripherals for Macintosh (monitors, graphic cards, etc...) Now, they sold TFT monitors and external HD : www.formac.com/webapp/index.php.
They sold monitors with G1 chassis under the name "Formac ProNitron 21/750". Of course this was exactly the same device than the DELL P1110 and Sony CPD E500. (chassis G1 - GDM-5403)
Later, they sold a "ProNitron 21/800" which was based on a DiamondTron tube. Not as good as the previous, unfortunately (i have one of these devices)
About your D1025TM : of course, 17 inch trinitrons or diamondtrons are extremely sharp. But the image is really to small to work.
I guess what Th3_Un1qu3 got is probably either an engineering sample/ early production batch or one modified by a reseller (using such convergence device or even the whole tube assembly from a P1110). Th3_Un1qu3, please tell me the date/place of manufacture of your p1130 set, which is printed on its back.
September 2003, Mexico.
Btw, i'm sorry for not mentioning a thing about the brightness drift mod anymore. A close friend of mine called and asked for some help with her upcoming exam, so i'm pretty busy. Should get done by the end of the week tho...
I've been thinking about an alternative involving a microcontroller, because the way i first thought it it would be pretty cumbersome to align. I have a couple PIC12F675 devices lying around, and they have ADC built-in, also software PWM is not too hard to do on them. The PIC can read the thermistor thru the ADC, and two buttons will set the degree of compensation that the PIC applies to the G2 voltage. This would be an effective and low parts count solution.
... That is, if i could remember where my Pickit 2 clone is. If i can't find it, i'll resort to the initial idea of using trimpots.
Sept 2003 mexico-made unit was probably one of the last production batch of p1130, maybe it's an improved version. Here we get 2001-02 Made in Japan units mostly.
Well, un1qu3, looks you are really an expert on electronics & single-chip microcontrollers, great. Hope you can succeed and get an ultimate solution on this monitor one day.
Once more question, un1qu3, you said you live in Romania, but your English is really great - Are you a native Romanian or a English-speaking person working in Romania?
Hmm, so they cheaped out on the Jap units then? That's surprising. My P1110 is made in October 2000 btw, and it says made in the UK.
I'm a native Romanian but my dad taught me English from an early age - he lived in the UK for a couple years. He used to bring me all kinds of books and tapes in English. I've gotten my first taste of electronics by helping my dad out with fixing the TV - he later quit this hobby, but i liked it a lot from the start so i decided to study more about it. I'm more patient than my dad when it comes to fixing things, and i'm very creative in coming up with my own solutions. I know several certified engineers that will turn down repairs if they don't have the exact part in stock - to me, that's just being lazy.
I'm not that much of an expert in micros - i was just curious about them last summer so i bought a pickit clone programmer and some PICs, and as i had some ASM experience for x86 i found them fairly easy to program. Not without their quirks, but not hard. It's funny how much blinking an LED and showing a few lines of text on a 16x2 screen can teach you.
Heh, i just hope i find that ultimate solution before the tube runs out of electrons, coz they aren't making any more of them. Though, i believe that just like tubes for audio, they'll make a comeback in a few years, so perhaps my skills will be put to good use then. I'm still hoping to get my hands on a FW900...
Icrontic's owner popping in here, just to say hi I know most of you don't venture out of this thread, but we do have a thriving and extremely welcoming and friendly tech and gaming community out there beyond the borders of Dell P1110 world
Thanks for the invitation, i'll consider it... The problem is that i'm a member of way too many tech forums so i have to stay off one or the other at times.
One thing that we do differently from other tech sites is offer a badge system for participation (pimp out your user profile with achievements!), weekly gaming events (such as a scheduled TF2 and BF3 server nights), and lots of in-person, real-life events, like Oktoberfest and St. Pattys for beer lovers, Expo Icrontic for LAN gaming, Summer Blast for BBQ, Renn Fest for huge nerds, etc.
Nothing to do with this topic, but imagine my surprise when i went out tonight, and as i walked down the stairs (i don't take the elevator at night, superstition), guess what i saw on the 2nd floor of my apartment building: A 28" Philips CRT TV! And with two flower pots on top so it blended in with the scenery. You have got to be kidding me!
The TV had its power cord cut off but it seemed as if it hadn't been messed with on the inside, so i moved the flower pots off it and took the set home. This time i DID use the elevator. I was right about it not being messed with: i found a ridiculous amount of dust inside, the only evidence of intervention being a sound converter attached to the TV tuner, and even the parts on that look over 10 years old.
Besides the dust, i found a shorted HOT and the reason why it blew - the capacitor between its collector and emitter was cracked. I happened to have spares on hand for both the transistor and the cap, and now i have a working 28" TV! It looks pretty darn good for its age, all i need now is a remote and it looks like i can finally get rid of the 24" Samsung in the living room. That thing has started to get on my nerves, it's been needing attention every few months in the past 3 years. Tube's going out and needs constant re-adjustment or the stupid protection circuit blanks the picture on brightness changes, such as during flashy adverts. (Hey, that actually might be a good thing)
Lucky indeed for getting a nice & big TV set for free! And it's even luckier that the damaged parts are relatively common this time. If some special part, for example the FBT, is damaged, you may have a difficult time trying to find a replacement. In my experience, TVs are often discarded because they broke down all of a sudden because of circult malfunction, but their tubes usually still have a long way to go. Hope the color balance of that set is correct - I never trust RGB gain/bias adjustment, since most imperfect color balance is caused by aged electron-gun or phosphor, rarely by resistor or AMP transistor. Color Adjustments only made the screen visible at a fixed brightness. Once the brightness is altered, the color will be biased again... Personally I've seen many high quality tubes (mostly Japanese-made) can keep its factory-set color balance for over 20 years. BTW, FW900 is also a G1-chassis monitor with 95% similarity to P1110. Thus it should also be affected by this annoying "over-brightness" problem.
Color balance is fine, thank you. White is neutral, not that bluish white found in sets made in 2000 and up. When you set the contrast to minimum the picture goes BLACK - a rare sight. With contrast so that the picture is barely visible, there is a slight red tinge but nothing major. Looks like this tube still has life left in it.
But back to our P1110. I figured out the G2 temperature control isn't such a great idea after all, as in itself it could be another source of drift... Because the circuit can only be optimized for one temperature point, and ambient temperature isn't constant unless you have aircon. Besides, not only brightness varies until warmup, but also position shifts slightly, so that would need to be addressed as well.
On the other hand i realized i've been ignoring the obvious. It'll sound really funny at first so i'm not revealing it now, i'll be trying my new idea out on my P1110 and if it works as expected i'll let you know.
I'm about to get another TV as well. I just fixed up an RCA projection TV and a good friend of mine bought it from me for a nice discount because I am getting his old TV. It is a Sony Trinitron KV-32FS13 that has a major color balance problem. Hope the tube isn't the issue.
Update on my p991: I will have time for sure this next weekend to find that annoying drift correct circuit. Since you are mentioning it might not be the best idea I'll hold off for now. Wonder what this new experiment of yours will be....
I just did a G2 adjustment to an excessively bright IBM P260. From 218 to 170 and seems ok. Still a lot to do with overall adjustment, but I believe this is very usable. I also have another P260 (slightly better to begin with) awaiting adjustment.
Everything went mostly as expected, not to mention WinDAS crashing all the time. I feel it might be important to mention that at first I got the "check RS232C" error while writing .dat to PROM, every time. I thought I had bricked the monitor but then realized the obvious solution that worked(after a couple of typical WinDAS crashes). It seems my RS232-TTL converter worked just fine when reading from monitor with just RX, TX, VCC and GND connected, but refused to write to monitor that way. Shorting the adapter's CTS to RTS was apparently necessary to successfully send the modified .dat to monitor.
So I went to play my favorite game, Audiosurf, and before I got a new video card, I was using a 9500GT which doesn't perform well with Audiosurf on high resolutions so I used 640X480 full screen. Recently when I go to this resolution from 1280X960 on my Dell, I get this: http://www.mojoimage.com/free-image-hosting-view-10.php?id=2350Sparks.jpg while the monitor is synchronizing to the lower resolution. The brighter bar on the left is very jumpy while it happens and the monitor lets out a loud high pitch ringing noise. I was thinking maybe the flyback may have a part in this. What could it be?
I just fixed my monitor by using a really cheap RS232<->TTL level converter based on the MAX232 from DealExtreme. It comes with a 4 pin header cable that splits into individual connectors at one end, so you can arrange the connections to match the necessary pin layout on the monitor. There is a mini-usb connector for external power (NOT for communication!), but don't use it if you already have the monitor +5v connected. It has LEDs for power, TXD and RXD. Another thing that struck me was the overall quality... uses a FR-4 board with a good quality solder mask and the soldering is excellent. All this for $2.60 and free shipping (be prepared to wait for many weeks)! See the link below for more info.
Been a while, eh? I've been doing more digging around and i've come to the conclusion that the brightness drift is NOT caused by:
G2 voltage Video amp (after the "drift correct" is bypassed) Tube Heater voltage
Cranking up the heater voltage resulted in the expected response of the picture getting BRIGHTER, so it appears that the tube neck temperature curve following the brightness drift is a mere coincidence. Now, i see that this monitor has a HV regulator, so my attention points to it. The fact that picture size and position also change slightly following the brightness reinforces the idea that this is a HV issue. Unfortunately i have no means of measuring EHT directly, so i'll have to probe around the chip for any drifting voltages.
Sony was kind enough to include detailed diagrams of every board and voltages at various testpoints, BUT the construction and mounting of the D board makes it basically impossible to probe live. The only solution as far as i can see is to cut the shield in the area where the HV reg is (the HV reg is SMD, on the bottom of the board).
Th3_uN1Qu3, are you saying that bypassing the drift correct isn't the answer? I was planning on trying that soon because my P1110 is dying. Most of the time it takes 2 tries to even get it to come on(the first try results in nothing but a blinking led) and even the degaussing cycle sounds sick.
Bypassing the drift correct only makes the P1110 behave like a P1130, which still has the brightness drift, only not that bad. It still takes 30 minutes to warm up, but that's better than 2 hours.
Your issue sounds like it has to do with the power supply (G board).
Okay, messed around witth the D board a little and did some measurements. Turns out the HV is stable as well. I have no means of measuring the EHT itself, so i just measured what goes in the flyback, but what comes out MUST reflect into what goes in since it's regulated, so it looks like the EHT isn't the reason either. I'm stumped.
About the only thing left for me to try is to try and keep the filament powered from an external supply while allowing the rest of the monitor to cool down, and see how it behaves when i turn it back on like that. If it still does it, this will rule out the tube 100%, but that still means we haven't found our problem.
Edit: You know, the best answer isn't always the correct one, but the safest one. For now, i'll be letting it be. The issue is more pronounced in the winter when it's cold inside, and right now it doesn't bother me. In fact, if you're used to how bad it was before you bypassed the drift correct circuit, you may not even notice it at all.
Besides, i'm not so sure i want to keep it anymore. I spotted a iiyama Vision Master Pro 21" for $25 locally. Those were expensive as hell back in the day and they're the best CRTs ever. Yes, better than our P1110s and P1130s - they do not have a glossy screen, thus they need no antiglare coating - no scratches. And the picture is better too. I had one of those a while back and managed to break it, because it was filthy and i washed it. I've washed electronics before and they ended up fine, but this one decided 1 day was not enough drying time for it, and it never powered the EHT up again. I felt really bad when i broke that one... looks like it's time for another one.
Comments
2. True. Too bad the warranty period has expired like 10 years ago.
3. Never had this one happen... when it's warmed up, it's warmed up, and all the adjustments done in the warmed up state will be the same the next time you turn it on and let it warm up. If thermal drift is so significant then there's something else wrong with it. I think this only applies to TV tubes. So far, all Trinitron monitors i've taken apart use the completely conventional approach to purity and convergence. Magnets on the tube neck and a dynamic convergence assembly on the side of the deflection coil. No wai, magnetic core memory was popular in the late 50s, but i can't see it being used now. Are you really sure the data isn't in the WinDAS file? Then there must be a separate area of the EEPROM which contains those settings. The EEPROM can be read/written using a programmer or another microcontroller. The existence of a separate area gives some answers, such as why disabling the "lowering contrast when increasing brightness past 50" option only lasts until you turn the thing off, and then it resets to doing it again.
With magnetic storage I didn't mean "core" memory, but that coils magnetize parts of the CRT somehow to change the linearity and levels of RGB gun outputs or such crazy stuff (e.g. by deflecting a part of the beam against a shield grid or what ever). Yes, that sounds overly complicated to be reasonable, but the CRT FAQ hint about modern Trinitron tubes suggested that such nasty hidden secrets may exist (perhaps invented to confuse competitors to complicate reverse engineering - remember the PlayStation 3 copy protection...).
But perhaps the calculated "colour return" correction data is simply directly output into a write-only memory (e.g. inside the RGB amp IC for faster access) where it can't be read back by WinDAS. I remember that in 1990th there were analogue audio sampling ICs (Hallmark Romcorder) to reduce chip size compared to conventional digital memory. Now think of what happens when the charge level inside such an analogue EEPROM(?) fades away over time. This could be well a reason for overbright picture or wrong colour curves.
I have another question regarding those monitors :
Does anyone knows if there's a way to increase the sharpness ?
Of course, we assume that it is perfectly adjusted with the two pots on the FBT.
I ask this because my two P1130 are not exactly as sharp as my P1110, although they all are well adjusted. They are a little "softer", compared to my old one.
(Of course this is not about geometry or convergence, which are well adjusted in all cases)
Maybe it's related to certain tubes better than others ? (of the same type, of course)
I have one P1110, one P1130, one CPD E530 (same chassis as P1130) and my best friend own two P1130.
( we are trinitron lovers...
And guess what ?
The best in term of contrast and sharpness is clearly my good old P1110 (a Formac 21/750 actually).
Maybe I'm lucky...
BTW, the “perfect” Trinitron computer monitor I ever used is neither a P1110 nor a P1130, but a ’99 17in V. Flat DELL D1025TM (CPD-200GS equivalent). After 12 years of daily usage, that machine is still extremely good in term of color balance / brightness / focus / convergence and never required any adjustment!
BTW, what is a Formac? I saw this name in windas but have no idea about this brand at all... maybe "For Apple Mac"?
Formac Elektronik GmbH is a European based manufacturer of various PC devices.
In the 90', they sold only peripherals for Macintosh (monitors, graphic cards, etc...)
Now, they sold TFT monitors and external HD : www.formac.com/webapp/index.php.
They sold monitors with G1 chassis under the name "Formac ProNitron 21/750".
Of course this was exactly the same device than the DELL P1110 and Sony CPD E500.
(chassis G1 - GDM-5403)
Later, they sold a "ProNitron 21/800" which was based on a DiamondTron tube.
Not as good as the previous, unfortunately (i have one of these devices)
About your D1025TM : of course, 17 inch trinitrons or diamondtrons are extremely sharp.
But the image is really to small to work.
Btw, i'm sorry for not mentioning a thing about the brightness drift mod anymore. A close friend of mine called and asked for some help with her upcoming exam, so i'm pretty busy. Should get done by the end of the week tho...
I've been thinking about an alternative involving a microcontroller, because the way i first thought it it would be pretty cumbersome to align. I have a couple PIC12F675 devices lying around, and they have ADC built-in, also software PWM is not too hard to do on them. The PIC can read the thermistor thru the ADC, and two buttons will set the degree of compensation that the PIC applies to the G2 voltage. This would be an effective and low parts count solution.
... That is, if i could remember where my Pickit 2 clone is. If i can't find it, i'll resort to the initial idea of using trimpots.
Well, un1qu3, looks you are really an expert on electronics & single-chip microcontrollers, great. Hope you can succeed and get an ultimate solution on this monitor one day.
Once more question, un1qu3, you said you live in Romania, but your English is really great - Are you a native Romanian or a English-speaking person working in Romania?
I'm a native Romanian but my dad taught me English from an early age - he lived in the UK for a couple years. He used to bring me all kinds of books and tapes in English. I've gotten my first taste of electronics by helping my dad out with fixing the TV - he later quit this hobby, but i liked it a lot from the start so i decided to study more about it. I'm more patient than my dad when it comes to fixing things, and i'm very creative in coming up with my own solutions.
I'm not that much of an expert in micros - i was just curious about them last summer so i bought a pickit clone programmer and some PICs, and as i had some ASM experience for x86 i found them fairly easy to program. Not without their quirks, but not hard. It's funny how much blinking an LED and showing a few lines of text on a 16x2 screen can teach you.
Heh, i just hope i find that ultimate solution before the tube runs out of electrons, coz they aren't making any more of them. Though, i believe that just like tubes for audio, they'll make a comeback in a few years, so perhaps my skills will be put to good use then. I'm still hoping to get my hands on a FW900...
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The TV had its power cord cut off but it seemed as if it hadn't been messed with on the inside, so i moved the flower pots off it and took the set home. This time i DID use the elevator.
Besides the dust, i found a shorted HOT and the reason why it blew - the capacitor between its collector and emitter was cracked. I happened to have spares on hand for both the transistor and the cap, and now i have a working 28" TV!
In my experience, TVs are often discarded because they broke down all of a sudden because of circult malfunction, but their tubes usually still have a long way to go.
Hope the color balance of that set is correct - I never trust RGB gain/bias adjustment, since most imperfect color balance is caused by aged electron-gun or phosphor, rarely by resistor or AMP transistor. Color Adjustments only made the screen visible at a fixed brightness. Once the brightness is altered, the color will be biased again...
Personally I've seen many high quality tubes (mostly Japanese-made) can keep its factory-set color balance for over 20 years.
BTW, FW900 is also a G1-chassis monitor with 95% similarity to P1110. Thus it should also be affected by this annoying "over-brightness" problem.
But back to our P1110. I figured out the G2 temperature control isn't such a great idea after all, as in itself it could be another source of drift... Because the circuit can only be optimized for one temperature point, and ambient temperature isn't constant unless you have aircon. Besides, not only brightness varies until warmup, but also position shifts slightly, so that would need to be addressed as well.
On the other hand i realized i've been ignoring the obvious. It'll sound really funny at first so i'm not revealing it now, i'll be trying my new idea out on my P1110 and if it works as expected i'll let you know.
Update on my p991: I will have time for sure this next weekend to find that annoying drift correct circuit. Since you are mentioning it might not be the best idea I'll hold off for now. Wonder what this new experiment of yours will be....
Everything went mostly as expected, not to mention WinDAS crashing all the time. I feel it might be important to mention that at first I got the "check RS232C" error while writing .dat to PROM, every time. I thought I had bricked the monitor but then realized the obvious solution that worked(after a couple of typical WinDAS crashes). It seems my RS232-TTL converter worked just fine when reading from monitor with just RX, TX, VCC and GND connected, but refused to write to monitor that way. Shorting the adapter's CTS to RTS was apparently necessary to successfully send the modified .dat to monitor.
http://www.mojoimage.com/free-image-hosting-view-10.php?id=2350Sparks.jpg
while the monitor is synchronizing to the lower resolution. The brighter bar on the left is very jumpy while it happens and the monitor lets out a loud high pitch ringing noise. I was thinking maybe the flyback may have a part in this. What could it be?
http://www.dealextreme.com/p/104325
G2 voltage
Video amp (after the "drift correct" is bypassed)
Tube
Heater voltage
Cranking up the heater voltage resulted in the expected response of the picture getting BRIGHTER, so it appears that the tube neck temperature curve following the brightness drift is a mere coincidence. Now, i see that this monitor has a HV regulator, so my attention points to it. The fact that picture size and position also change slightly following the brightness reinforces the idea that this is a HV issue. Unfortunately i have no means of measuring EHT directly, so i'll have to probe around the chip for any drifting voltages.
Sony was kind enough to include detailed diagrams of every board and voltages at various testpoints, BUT the construction and mounting of the D board makes it basically impossible to probe live. The only solution as far as i can see is to cut the shield in the area where the HV reg is (the HV reg is SMD, on the bottom of the board).
Stay tuned.
Your issue sounds like it has to do with the power supply (G board).
About the only thing left for me to try is to try and keep the filament powered from an external supply while allowing the rest of the monitor to cool down, and see how it behaves when i turn it back on like that. If it still does it, this will rule out the tube 100%, but that still means we haven't found our problem.
Edit: You know, the best answer isn't always the correct one, but the safest one. For now, i'll be letting it be. The issue is more pronounced in the winter when it's cold inside, and right now it doesn't bother me. In fact, if you're used to how bad it was before you bypassed the drift correct circuit, you may not even notice it at all.
Besides, i'm not so sure i want to keep it anymore. I spotted a iiyama Vision Master Pro 21" for $25 locally. Those were expensive as hell back in the day and they're the best CRTs ever. Yes, better than our P1110s and P1130s - they do not have a glossy screen, thus they need no antiglare coating - no scratches. And the picture is better too. I had one of those a while back and managed to break it, because it was filthy and i washed it. I've washed electronics before and they ended up fine, but this one decided 1 day was not enough drying time for it, and it never powered the EHT up again. I felt really bad when i broke that one... looks like it's time for another one.