Sony GDM-FW900 - Help Me Fix It?

[jrodefeld]

I've been having some trouble with my Sony GDM-FW900 CRT monitor off and on for the past six months or so.

Usually it's been working okay if I keep it on all the time. If it gets turned off, then I'll have a hard time getting it to turn on again. It will either display an image for a second, then turn off and the green light will turn to yellow and blink.

Sometimes it won't turn on at all and will immediately start flashing yellow.

I shot a video of what it's doing:

https://www.youtube.com/watch?v=_O-Y...ture=emb_title


Anyone have any idea of what the problem is?

I actually have another FW900 that is also not working that I could take parts from if needed.

Hoping someone here could shed some light on what might be wrong.

Thanks!

[stj]

Re: Sony GDM-FW900 - Help Me Fix It?

sounds like a bad capacitor - caps work better when warm.

you can check this theory with a hair dryer by heating different areas of the boards till it fixes it(temporarily)

[momaka]

Re: Sony GDM-FW900 - Help Me Fix It?

sounds like a bad capacitor - caps work better when warm.

Could be. Though Sony uses good quality caps (Rubycon, Nichicon, and United Chemicon) - GP usually, but still good quality nevertheless.

I suspect bad solder joints, though. The newer Sony CRTs (both TVs and monitors) are actually pretty notorious for bad solder joints, so I suggest the O/P to open his monitor and check everything. In particular, look at the G-board (power supply) first - any component mounted to a heatsink should have its joints checked throughly. On both of my GDM-FW900 monitors (one has a shot tube, but does power On still), the G-boards had lots of cracks around the heater and standby regulators. Coincidentally (or not), one would not come out of standby (i.e. sit with an orange LED light.) After reflowing the solder joints on the G-board, it came back without issues and has been working ever since. The other one had its power supply working, but had an arcing tube (lost vacuum - something that also isn't unheard of with these 24" Sony CRTs.)

**EDIT**
I watched the video, but have not seen this failure before where the picture slowly shrinks to a tri-color pattern. With that said, you may also have to pull the D-board out and inspect all solder joints on the horizontal output transistor and also all chips attached to a heatsink.

As for the blinking seen on the image before the picture went out - that seems like a classic modern Sony "G2 over-brightness" issue, which is a separate problem. For that one, you may need to do some work on the A-board (the board attached at the back of the tube.) Give me a few minutes, and I will edit this post with a link regarding information on that...

***EDIT 2***
Here is more info on the G2 over-brightness issue:
https://www.badcaps.net/forum/showpo...7&postcount=25

Removing the cutoff amp self-biasing circuit in a nutshell:
https://www.badcaps.net/forum/showpo...7&postcount=46

WinDAS software:
https://www.badcaps.net/forum/showpo...8&postcount=24

Some things to keep in mind when using WinDAS:
https://www.badcaps.net/forum/showpo...33&postcount=4

I think that covers the G2 over-brightness issue. But if not, I will add more. Or feel free to ask questions.

[R_J]

Re: Sony GDM-FW900 - Help Me Fix It?

would have been nice to see a picture and not that screensaver. It seems to flash red with retrace lines before it went out, Check the connections on the C board (crt neck board) and then check the connections on the A board on ic403, ic406 and cn407. that could also indicate a shorting red gun in the crt

[stj]

Re: Sony GDM-FW900 - Help Me Fix It?

i hope it doesnt go full-field,
widescreen tubes with narrow necks are notorious for gun-shorts!
usually blue or green because of the tube orientation

[CapLeaker]

Re: Sony GDM-FW900 - Help Me Fix It?

i hope it doesnt go full-field,
widescreen tubes with narrow necks are notorious for gun-shorts!
usually blue or green because of the tube orientation

My 12 gauge will fix that permanently, doesn’t matter the orientation!

[stj]

Re: Sony GDM-FW900 - Help Me Fix It?

that's only the enviromental disposal though, not the obtaining of a replacement!

i did fix one in a philips tv once though, i flipped the tube upside-down and re-wired the scan coils.
it's not always possible though because the anode ends up very close to the boards!

[brownvim]

Re: Sony GDM-FW900 - Help Me Fix It?

Hi Guys,

I have a similar problem with my GDM-FW9011 and its been getting worse over the years, takes around 5 mins of me turning it on and off before it stays on.

My monitor goes green though, not red. I could post a video?

jrodefeld did you manage to fix yours?

momaka im going to try the fix you posted on the A Board and do the WINDAS adjustment after.

I have read opening the CRT can be very dangerous, what precautions should i take? is there a video of someone dismantling one?

[elesin38]

Re: Sony GDM-FW900 - Help Me Fix It?

classic modern Sony "G2 over-brightness"

I just wanted to say huge thatnks to you and @Th3_uN1Qu3 for exporing and sharing the info about that issue.
I've just fixed an FW900 I've recently bought by following your messages.
You are my heroes

[stj]

Re: Sony GDM-FW900 - Help Me Fix It?

good news.
btw, your lucky to be in moscow - i think it may be the only place that still has a chain of electronic component stores!!!

[elesin38]

Re: Sony GDM-FW900 - Help Me Fix It?

Well, I was celebrating a bit early. The OSD colors are now fine with deep dark black (date of manucaturing info screen for example), but the picture from PC is still greenish.

Looking at the schematics it looks like the issue maybe somewhere on the path through the IC401 (INPUT SELECT) to the IC402 (RGB DRIVE) where the OSD and VGA picture are mixing together. Seems logical?

[stj]

Re: Sony GDM-FW900 - Help Me Fix It?

if you have a scope or good multimeter you may be able to trace it by grounding the 3 inputs or linking them all together and then comparing the 3 signals as they leave each chip

[elesin38]

Re: Sony GDM-FW900 - Help Me Fix It?

if you have a scope or good multimeter you may be able to trace it by grounding the 3 inputs or linking them all together and then comparing the 3 signals as they leave each chip

Thanks for answers!
Yeah, we a nice choice of real stores with electronic components here

All of the electrolytic capacitors on A board are severely out of their spec, all of the 47nF ones are measuring to 34-37nF, C467 is rated to 1uF, but it's measuring to 300 nF.

Guess I'll start by recapping all of the electolytes on that board.
If that would not help, the IC401, 402 and 403 are available on aliexpress, so I could swap them too

[momaka]

Re: Sony GDM-FW900 - Help Me Fix It?

I just wanted to say huge thatnks to you and @Th3_uN1Qu3 for exporing and sharing the info about that issue.
I've just fixed an FW900 I've recently bought by following your messages.
You are my heroes

Nice!
Good to hear someone is still interested in these old CRT beasts.

All of the electrolytic capacitors on A board are severely out of their spec, all of the 47nF ones are measuring to 34-37nF, C467 is rated to 1uF, but it's measuring to 300 nF.

Guess I'll start by recapping all of the electolytes on that board.
If that would not help, the IC401, 402 and 403 are available on aliexpress, so I could swap them too

Keep us posted and let us know what you find.

I suppose it's not too surprising that some of the caps are starting to go out of spec. After all, even these "latest" CRT monitors are approaching close to 20 years now. I would also suggest to check some of the clear-looking film caps (the gray/semi-transparent plastic ones, which I think are either PP or PE.) I read somewhere that when their plastic starts turning yellow, they too could be possibly getting out of spec, due to sealing issues. Can't confirm if that is true or not without taking one of mine apart and checking... and I have both of these monitors burried deep into storage, ATM.