Hi guys! I'm quite new to SGI and old hardware in general. I have an SGI GDM-20E21 monitor that seems to have died. :(
The Story:
I pulled an old SGI GDM-20E21 monitor out of my parent's basement and attached it to my dreamcast via a VGA cable. Every time I started it up I heard a bunff 60 hz which I assume is a degauss noise. I also heard crackly static noises like normal. It started at half width and eventually fanned out until it took up the whole screen but the lines were all interlaced incorrectly and wobbly for like 2 minutes until it all stabilized. My father says it's "always" done this. Once stabilized it looked amazing with no convergence or sync issues, etc. When I would turn it off I would hear the usual crackly static noises.
One day I started it up and while it was slowly correcting its sync issue like normal the image all of a sudden got smaller and darker and then disappeared. Upon turning the monitor off and then on again, I heard no degauss noise, crackling or anything. Silence. Now the monitor constantly has a blinking yellow power led, and I can't turn the monitor "off" like the led won't turn on or off with the power button. I guess it's never turning on in the first place because of some errors/issues?
The Symptoms:
*No degauss at startup. No fun crackly noises anymore :(
*Constantly blinking yellow power LED under all circumstances
*Power button doesn't really change anything when pressed.
*+B Detect error in Sony DAS.
Information I've gathered so far:
There's another post on this forum:
http://forums.irixnet.org/thread-2990.html.
This post has the same monitor but with slightly different symptoms. I think I was able to get further than them with a better match on the Sony monitor service manual and I was able to get further than them with a more compatible version of MS-DOS Sony DAS instead of WinDAS. The rest of the post basically boiled down to telling them to do a recap which is good advice and i'll do that myself once I order the caps and a desoldering gun.
The GDM-20E21
user manual says that blinking power LEDs mean a possible monitor malfunction. Thank you SGI very helpful.
This monitor appears to be similar to the "Sony GDM-20SE2T" with the "n2h chassis" so the
service manual for that has a lot of similarities with mine. The G board (Power board) is even nearly identical barring a couple silkscreening inconsistencies!
Service manual at:
https://elektrotanya.com/sony_gdm-20se2t...nload.html
I should hopefully have some luck sourcing caps using this manual if I go down that route.
I got a bunch of Sony DAS information off this very useful youtube video:
https://www.youtube.com/watch?v=Lt1NtRH4BOg
which gives cracked versions of the sony DAS software. I found that the GDM-20SE2T monitor I think is like mine is in the JA101 sony das version folder and that version of sony das seems to be able to communicate with my monitor. No idea if adjustments work correctly or anything else for that matter. I was able to get this working on a windows XP laptop with a USB rs232 TTL converter I use for arduinos. I installed windows xp compatible drivers from 2012 for the rs232 chip on my module directly from FTDI's website. The COM port was set to COM5 by default and I don't think DOS likes that so I set it to COM2. My other windows xp computer didn't work and it was set to COM3. Maybe that was the reason it didn't work? The DOS based sony DAS software doesn't allow you to choose the com port your monitor is on but I didn't work on setting DOS environment variables to line up the ports because I didn't think of it. Anyway if your DAS software isn't connecting to your monitor but you know the rs232 module works on your XP install (By shorting rx and tx and seeing loopback work) it could be COM port shenanigans.
When I opened the failure information page in the program I got normal for all the issues except for "+B Detect" which had an error. Literally no idea what this means. Maybe beam voltage or something?
My (Likely flawed) diagnosis and plan:
The degauss isn't going at startup and I hear no crackles so I suspect the power board (Board G on this model).
I inspected the G (power) board by eye and can't see any cracked solder joints or leaky capacitors. No burns either. Everything looks good minus the dust.
There's a fuse on the G board and I checked it's resistance is 0 so it appears good. :(
I should probably recap the board since even though they all look fine they could probably be bad?
What I need help with before diving into a recap of the power board:
* If someone has the service manual for my SGI GDM-20E21 I would love them forever. The user manual is not super helpful.
* Does anyone have a better match for this monitor than the the Sony gdm-20se2t?
* Does anyone know what this +B Stop error means? Googling and ChatGPT lead me in the direction of it being like a power beam voltage issue but I don't know for sure and have no idea what to do with that info other than maybe poke the board with a multimeter while it's running.
* Has anyone had a similar situation and what helped in it? Is this a common issue that has an easy resolution?
* There's a spec for the voltages for every pin on every IC on each board in the service manual. With this info are there any voltages that jump out to you that I should be checking? I don't wanna do much live probing on this thing since I'm aware of how scary this G (power) board is.
* Other forums that I could ask on that might help
* Please send help I don't know what I'm doing
(past: 
)