VOGONS


First post, by Boohyaka

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Hi guys,

Long time reader, first time poster. I recently broke the promise I made myself to stick to emulation and never purchase old PC hardware, and honestly couldn't be happier (and coping well with my wife's eye rolling, haha). Which means I'll have a good reason to try and be a more active part of this community, and hopefully benefit from the incredible amount of knowledge hanging around here.

So I scored pretty much big time by finding a Sony Trinitron Multiscan CPD-G500 screen for basically free. Those are superb 21" monitors. It works quite well, except that I immediately noticed the screen was too bright and suffered from a kind of greenish tint. During BIOS, it's obvious the black is not deep black, even with brightness set to 0. It almost looks like there is a back light, if that makes sense. And the black, with the screen reset to defaults, definitely look greenish.
I attached a picture snapped with my phone, the problem is even exacerbated, it looks greener than reality!

By turning brightness to 0, raising the red and setting the green to 0, I almost get something that looks like a normal picture, but definitely not perfect.

Googling around I did not find anything specific to monitors, but found some topics of green tint on Sony CRT TV's, apparently a common issue, but I'm not really sure it applies to my case.

- Would anyone know what is happening, and/or know ways to make a better diagnostic?
- I am quite well equipped with tools, (de)soldering station, etc.. but I am definitely not very experienced with them, I got basic soldering skills. I also know CRT can be dangerous to open and work with. Does it seem possible and reasonable to service it myself with proper direction?

Also to let you know I tried different VGA cables and different computers/graphic cards, it's definitely the screen.
Let me know if there's any other information I could provide.

Thanks a lot guys, hope can someone help me restore this beautiful screen to its former glory!

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Reply 1 of 28, by Doornkaat

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Hey and welcome to the forum. 😀

While it is certainly not as hazardous to work on an UNPLUGGED(!!!) CRT as many claim it was, being rather inexperienced working with and troubleshooting CRTs and similar devices it is very possible you'll do more harm than good. So if you want it fixed I suggest you take it to an experienced technician or practice troubleshooting with some dispensable CRTs first.
As far as I know (and I'm no expert by any means) a common problem with Trinitron CRTs is one electron gun giving up much sooner than the others. In this case the tube itself has to be changed and sourcing a replacement will be very tricky by now. 🙁

As for safety precautions:
The tube is operated at very high voltages and acts as a capacitor holding a charge for long after it's turned off. There usually is a bleeder resistor in there that is supposed to discharge the tube but that can fail and should not be relied on. This is why the tube should be properly discharged before working on it. The low capacitance of the tube is not enough to kill a healthy person, even at scary voltages like 25000-30000V, but it will hurt quite a bit to become the discharge path and you might get secondary injuries from the inevitable twitch. Also if you don't pay attention when discharging the tube you might fry other components within the assembly.
Same as with all switching PSUs there are also large mains voltage capacitors within the power supply that can hold a charge and give you a good shock.

I know there are many sensational stories of CRT discharges on the web, so don't take my word for it but that of Prof. Thomas H. Lee from Stanford University.
Yes, a 9 inch Mac CRT is much smaller but still a 21 inch CRT discharge does not hold more electric energy than a single impulse from an electric pasture fence.

Reply 2 of 28, by Boohyaka

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Hello, and thank you!

Thanks for sharing the article! That was a great read. It's true that we immediately associate high voltage with danger. Also thanks for all your good advice - I definitely don't want to risk doing more harm than good, I really like that screen and would love to give it a lot more years of use. Basically the point of this topic was to check if there was some known issue that was easy to fix. Unfortunately it seems you're saying there is potentially a known issue that is NOT easy to fix 🙁

I will wait for more input, but in any case I was already trying to find a proper technician in parallel.

Reply 3 of 28, by imi

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you could try a factory reset or if there are any adjustments in a service menu that help... other than that there might be adjustments for the colors inside somewhere.

service manual: https://elektrotanya.com/sony_cpd-g500.pdf/download.html
obviously be careful when working inside.

it might be something that can be fixed with a few simple adjustments, or it might not be.

Reply 4 of 28, by Boohyaka

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Thank you for the service manual link, that can be very useful!

I did reset the screen and it's definitely not normal, even after a factory reset. As said I can improve it by using the color adjustments and controls, but it's not great, there definitely is an issue.

Reply 6 of 28, by Doornkaat

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Boohyaka wrote on 2020-02-13, 12:53:

Hello, and thank you!

Thanks for sharing the article! That was a great read. It's true that we immediately associate high voltage with danger. Also thanks for all your good advice - I definitely don't want to risk doing more harm than good, I really like that screen and would love to give it a lot more years of use. Basically the point of this topic was to check if there was some known issue that was easy to fix. Unfortunately it seems you're saying there is potentially a known issue that is NOT easy to fix 🙁

I will wait for more input, but in any case I was already trying to find a proper technician in parallel.

Again I am by no means an expert on CRTs and I can not give a reliable diagnosis. An overly green picture can be caused by many factors including but not limited to the gun. It may be something as simple as a degraded resistor or transistor which can be easily replaced or even just a connection issue on the neck board. A skilled technician can determine the issue quickly and as long as the tube is ok they will be able to repair the fault as well. Maybe you know somebody who knows a retired television technician who'll do it for a couple of bucks or maybe there's a repair cafe nearby, they tend to have just that kind of people. 😁
Generally I'm an advocate of doing it yourself. If it was some random used 17 inch CRT that can easily be replaced with another used one for a couple of bucks I would tell you to get a service manual and go to town on it! 😉
But because this is something that may be a little harder to reaquire and the fault is not easily determined maybe this is not the best place to start learning.

Whatever you decide to do with it I hope it ends with the screen working perfectly again! 😀

Reply 7 of 28, by ShadowofBob

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Try letting the monitor warm up for 30min then going into the menu then color options. Use the "Image Restoration" feature. If that doesn't work I'd recommend the WinDAS guide over at HardForum. Even if Image Restoration fixes most of your issues I'd still advocate a WinDAS calibration if you can as these greenish tint on black issues are usually a G2 voltage fix that is controlled via WinDAS. I adjusted my P1130(G520) and it was well worth the effort.

https://hardforum.com/threads/windas-white-po … n-crts.1830788/

Reply 8 of 28, by Boohyaka

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Many thanks ShadowofBob! Image Restoration I already tried and made 0 difference. The WinDAS calibration's interesting, I quickly glanced over the link you sent and it was a lot of info, quite overwhelming, I need to take some time to go through it 😀 looks like I'll be needing hardware? I'll read it and come back if I have questions, thanks again 😀

Reply 9 of 28, by ShadowofBob

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Yes, it's rather daunting the first time you read through it. Took me a while to gather everything then dedicate a couple dark hours to calibrate the monitor.
Hardware wise you'll need:

  • a USB or RS232 to TTL adapter/cable
  • a spare floppy power cable to use as the connector to the monitor(the pins on the monitor for the TTL connection's are larger than standard pin headers for most motherboards and can break the usual quick connectors/pins when removing if you don't use a floppy power cable).
  • A colorimeter such as the i1DisplayPro or DTP-94(Both of those are the preferred colorimeters)
  • A computer to run WinDAS and connect to the TTL adapter
  • A computer to drive the monitor and display test slides

Here's another thread that more details the setup. Check the back of your monitor. I had a little removable plastic flap and did not need to remove the shell of the monitor to attach the TTL adapter. You can see the larger pins while this person didn't use a floppy power cable those quick connects are probably not useable on anything else again.
https://forums.blurbusters.com/viewtopic.php?t=504

Reply 10 of 28, by Boohyaka

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YES! You just gave me a lot of hope 😀 I actually found by myself one of the links in that thread you just shared and was currently reading it:

http://www.piclist.com/images/com/geocities/w … /gregua/windas/

I'm currently looking into sourcing a cable, if you have any tip please let me know!

Reply 11 of 28, by ShadowofBob

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I just used this RS232 to TTL adapter: https://www.amazon.com/gp/product/B01JYNHNW6/ … e?ie=UTF8&psc=1
If your computer doesn't have a Serial port then this should work just as well: https://www.amazon.com/Adapter-Serial-Convert … s/dp/B075N82CDL

Don't forget a Serial extension cable if you go the serial RS232 adapter route.

Reply 12 of 28, by Boohyaka

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Great I found a local cheap USB-TTL adapter, that should do it. I also found a "cheap" i1 DisplayPro, i've been wanting to get a calibration device for a long time.
I hope I'm giving this beauty a new life! 😀 thanks to you again

Reply 13 of 28, by Boohyaka

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Going link to link from what you shared, and other links I found, I ended up on this thread that seems to be some kind of mother of all threads on this problem:

https://icrontic.com/discussion/19549/dell-p1 … tor-too-bright/

So glad I posted here and you came around ShadowofBob, you're the man! This sounds exactly like my issue. Apparently, it's very well known, particularly on Sony G500....the model I have. Yay! At first people solved it by soldering a resistor inside it somewhere, until someone further down the thread reverse-engineered the Sony DAS stuff and managed to achieve better results through software.

The hope is very much alive! I ordered everything I need and can't wait to try and solve it! Will keep you posted 😀

Reply 14 of 28, by fitzpatr

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I would strongly recommend following the Image Restoration path a couple more times before doing anything else. I have the exact same monitor, and had the exact same problem. Run it for a good while with a signal, and then use it again. Mine was just as bad when I powered it up after receiving it, and it fixed it perfectly.

MT-32 Old, CM-32L, CM-500, SC-55mkII, SC-88Pro, SC-D70, MU2000EX
K6-III+/450/GA-5AX/G400 Max/Voodoo2 SLI/CT1750/MPU-401AT/Audigy 2ZS
486 Build

Reply 15 of 28, by duga3

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Definitely run WinDAS as ShadowofBob suggested, it is the best way to align everything again. Image Restoration is a feature available only on a handful of monitors and is meant as a last resort if you do not have the time/tools to perform the white point procedure from WinDAS. After calibration you should never press Image Restoration again because it will mess with the calibration, so you will need to perform the (much better) white point procedure again (or just load the backup .DAT memory file).

I calibrate in total darkness. Note it really takes a couple of minutes for your eyes to adjust to the dark. During the G2 step I have a full black pattern loaded and adjust G2 until it is invisible. By invisible I mean totally black but not any more than it needs to otherwise it will be crushing shadows and later washing out saturated colors if you try to fix the shadows with ICM calibration. On some CRTs YMMV with this step so if something is not working in your case, try a different approach.

98/XP multi-boot system with P55 chipset (build log)

Reply 16 of 28, by Boohyaka

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Simply fantastic!

So I had already tried Image Restoration several times with no change whatsoever. Today I received the USB-TTL adapter and already fixed a proper cable two days ago, so I could go ahead with WinDAS today. After a bit of struggling with making the software work (in the end I've had to install XP on a laptop for it to work, in spite of people saying it worked for them under Win7) and also TX and RX cables are reversed for some reason. After reading the screen settings in WinDAS, the G2 was set at 177, and after several tries I ended up reducing it to 140 to get a very good black. Yay, problem fixed! Or was it completely? It was still a bit on the greenish side. I tried another Image Restoration, and this time it came out PERFECT! I'm so happy 😀 one of these days I'll try to do a proper calibration to get the best out of it. It really is a wonderful screen.

Thanks to ShadowofBob first of all, and all the advice from everyone else, you guys are great. Awesome!

Reply 18 of 28, by duga3

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WinDAS works in later Windows as well, running it there myself, just need a bit of fiddling.

TX should connect to RX. RX should connect to TX. ("sender" to "receiver" basically).

G2 of 177 is very high.

98/XP multi-boot system with P55 chipset (build log)