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Author Topic: Issue with Sony Trinitron Monitor - Wavy Display  (Read 802 times)

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nick3092

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Issue with Sony Trinitron Monitor - Wavy Display
« on: October 08, 2019, 10:20:00 pm »
I have a 20 or 21" SGI monitor (Basically its a Sony Trinitron) that I use in my MAME cabinet.  I turned it on for the first time in a little while last week, and was greeted by some rather nasty horizontal blurring.  It seems to happen on the OSD as well, even when there is no image. I found the service manual for the monitor (link below), and proceeded to open it up, discharge the anod, and removed the power board, hoping maybe it was just a bad cap there.

I put it on my work bench and I was getting zero voltage on all the rails except the 8v standby rail.  Knowing that couldn't be right, I figured maybe the board needed a signal to come out of power save mode.  After consulting with someone smarter than me on it, they suggested putting some current on the POWER SW header.  The most convenient thing to do was to jumper that to +8 standby.  So I powered it up by jumpering the 8v standby power header to the power sw header and started to see voltage on the other rails.  I checked all the rails with my DMM, and got the following:

+8 standby = 7.76vdc
-15 = -17.4vdc
+15 = 16.7vdc
+80 = 93.3vdc
+200 = 251vdc

I also took screen prints of each rail on my Rigol scope.  But nothing jumped out at me as being bad.  When DC coupled, they all seemed to generate a fairly flat stable line.  The 80 and 200 rails had maybe a slight looking ripple/wave on DC, but didn't look like much.  The +/-15 rails were pretty much solid flat lines though.

I then ran the scope over them all AC coupled.  They all seemed to have the exact same looking noise/wave on the line.  If the scope's measurement is to be believed, its somewhere in the neighborhood of 170kHz and ranging from 80-100mV.

I noticed that there was a higher pitched buzz/whine coming form the board somewhere.  hard to say from where, but I think it was T640.  I also noticed that sometimes the noise wasn't there.  Particularly if i messed with the power sw jumper I made.  But I don't think my jumper was bad, as sometimes I would flip the mains switch off when there was no noise, not touch the jumper or even bump the board in the slightest, and the next time I flipped the mains on the noise was back.  I also noticed that when the whine/buzz went away, the +200v rail went up to 283vdc.

Thinking maybe there was something wrong with the 200v rail, I checked the voltage provided on the schematic for IC630.  Which the schematic labels a 200v regulator.  And oddly, this doesn't look like any voltage regulator I have seen.  There is no heat sink.  Its just a rectangular SIP chip with a square bump on the back, and on the front it says DM-60 NMB.  On pin 3 it should be 2.5v, and both when the whine was present and not, I got 2.54-2.57v.  So no issue there.  Pin 4 is a different story.  Either the voltage list is wrong, or I have a fault somewhere.  The chart says pin 4 should be 11.6v.  However, I only get 1.9v regardless of the whine being present.  Of course it's possible the voltage chart has a typo of an extra 1.  I would love to find some kind of data sheet to confirm what this IC expects, but I cant.

My friend I was consulting with thinks there is no issue on the power board, and rather I should turn my attention to the deflection board.  Specifically the areas around IC010 and IC007 which handles hsync. However, removing that board is kind of a pain, due to the fact I can't seem to get the two wires that go to the neck of the CRT to disconnect from the FBT.  And Sony decided to use the tray the PCB mounts to as a giant heat sink, so I'm going to have to clean off and reapply a ton of thermal grease.

Before I go any further, I thought I'd see if anyone here would have some advice.  My cabinet was somewhat built around this monitor.  So I really want to get it working again.  If it's as simple as recapping the power board, I can handle that.  If it's something n the deflection board, not sure I'm up to that.  I'm also not sure if I could find anyone local to repair it.  But I haven't looked really, so I can't say for sure.

TIA for any advice.  And here is the schematic:

https://www.manualslib.com/manual/990031/Silicon-Graphics-Gdm-5011p.html

buttersoft

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Re: Issue with Sony Trinitron Monitor - Wavy Display
« Reply #1 on: October 09, 2019, 10:54:38 pm »
I don't have any better repair advice than to test the voltages like you have been. For diagnostic advice, however...

That monitor has the ECS port for serial interfacing. It's under  the cover (part #24) shown on page 34 of the service manual you linked to, and the ECS pinout is shown in a few other places. It's a four-wire serial link but without the +5V as power comes from the monitor itself. I think this means you'll be able to interface with the service side of things using the Sony WinDAS software. I think the vid and description at this link is a good place to start - .

You can find a "hacktivated" copy of WinDAS floating around, if the one linked on that vid isn't it. It did take me a fair bit of googling to find it originally.

I've used the software but i haven't had to fix anything with it, the monitor i was looking at had been dropped and has physical damage as well. You can play with some voltages in the software like the screen voltage, but i don't know if it's going to be enough. IT was never designed for consumer use though, and you have to figure things out and make hexfile changes to update things.
« Last Edit: October 09, 2019, 10:56:33 pm by buttersoft »

nick3092

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Re: Issue with Sony Trinitron Monitor - Wavy Display
« Reply #2 on: October 12, 2019, 06:06:46 pm »
Thanks for the advice.  But I think at this point it may be beyond what I'm comfortable handling.  I put the power board back in the chassis, and powered it back up.  I could easily access IC630, so I took voltage readings again.  This time the 200v was at exactly 199v.  Pin 3 was still at 2.5, but now pin 4 was reading 5.4v, which is more than I got on the bench previously (1.9v), but still lower than the schematic (11.6v).  And I still think I could hear something buzzing/high pitched noise from the power board, but not 100% sure.

I'm not totally convinced though its a power issue, I'm beginning to lean more towards something on the deflection board.  And without knowing how to get the two wires off the fly back, I can't remove the board.  I was able to get a decent look at it though.  I didn't see any obvious leaking/bloated caps.  So I'm not sure what the issue could be.

Looks like I might be trying to track down someplace to repair it.  If anyone has suggestions for someone/someplace in the SE WI area, please let me know.

Mr. Peabody

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Re: Issue with Sony Trinitron Monitor - Wavy Display
« Reply #3 on: October 15, 2019, 08:16:19 pm »
Or get another.

nick3092

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Re: Issue with Sony Trinitron Monitor - Wavy Display
« Reply #4 on: October 15, 2019, 08:37:14 pm »
Not exactly a helpful reply. It's not like 20" Sony Trinitron monitors are readily available, let alone for a remotely decent price. And that's not even factoring in the fact it would most likely have to be shipped to me. At 70lb and it's size, that's not cheap either. I bought this for $20 or $25 like 12 years ago. Not to mention any other one I find could wind up suffering the same issue. I'm way better off trying to find someone local(ish) that is capable of repairing it.

Mr. Peabody

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Re: Issue with Sony Trinitron Monitor - Wavy Display
« Reply #5 on: October 18, 2019, 01:35:27 pm »
Look on CL/local 'groups'. Someone here in your area might have one.....