Issue with Sony Trinitron Monitor - Wavy Display

[nick3092]

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]

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.

[nick3092]

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]

Or get another.

[nick3092]

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]

Look on CL/local 'groups'. Someone here in your area might have one.....

[nick3092]

I'm reviving this thread, to see if I can maybe find anyone who has an idea of what is going on with this monitor.  Or can at least help me troubleshoot it further.  I was unable to find anyone around here who still works on CRT monitors, so self repair seems to be the only option here.  But I don't know how to troubleshoot a CRT.

Between October and now, I have ruled somethings out.  I found the voltage readings I was getting earlier in the thread when bench testing the power board were inaccurate on the bench.  The board does not like being run outside the chassis for somereason.  The readings look very good while the monitor is in the chassis:

-15v rail (measured -14.5v)
+15 rail (measured 14.5v)
+80 rail (measured 78.2v)
+200 rail (measured 199.3v)

I figured out how to disconnect the fly back so I could remove the deflection board.  So I recapped the board.  No change.  Since then, I have replaced pretty much every electrolytic capacitor in the monitor, board by board, checking the monitor after each one.  No change after any of the recaps.  I looked over the deflection board for any broken/cracked solder joints, I couldn't find any.  To be safe, I reflowed a bunch of joints on the board, focusing on anything attached to a heatsink.

I did notice that the ripples running up and down the left and right sides of the screen change slightly if you mess with the geometry settings.  Except in one spot on the screen.  This spot on the screen never changes.  Its always the static plateau, valley, plateau, valley while adjusting it.  Not sure if that means anything.

Its possible whatever this is, is a defect across all similar Sony chassis.  Someone else found an eBay listing of a Sun monitor with a Sony chassis exhibiting the same thing.  Although, it looks worse than mine.  And according ti the service manual, for that monitor, the deflection board is about 99% identical to mine.  So my money is on a common issue with this monitor.  The million dollar question though, is what?
https://www.ebay.com/c/13014969428

I have a scope and can post screen prints of any points of interest.  but I'm not that great with using it or troubleshooting CRT's.  So I need to be told exactly where to check, preferably with what scope settings as well.  Due to the construction of the monitor, its almost impossible to get to the back of the deflection board though, so almost any measurements have to be taken from the component side.

This is a really nice 21" monitor and I would love to be able to get it going again.  My cabinet has been idle way too long.  I could have used the distraction of playing it the past 2 months.  Hopefully someone can help me fix this.  I know its a bit more complex than your usual arcade monitor, but the core functionality/troubleshooting should be the same.

Thanks!

[Zebidee]

I'm shooting from the hip here, because I don't know your monitor at all and I'm far from the most knowledegable person on these boards, but I would have a look at the horizontal deflection circuit - identify the ICs that do the job, "horizontal deflection oscillator", nearby components and power supply to that part of the circuit.

If you have horizontal deflection then you have power (and obviously vice-versa) as horizontal deflection drives the power circuit. If the B+ looks good then it must be in the deflection circuit. Fluctuating power might possibly cause the problems you have, but even then a possible cause could be the horizontal deflection or the part of that circuit (optocoupler) which feeds status info back for regulating the B+.

That is a long way of saying if you have power at all, then the part(s) responsible are failing but haven't completely failed yet.

It is pretty base advice, but some "swaptronics" (swapping out suspect parts like ICs for known good ones, not just electro caps) in horizontal deflection area might reveal your problem or at least rule some things out.

[nick3092]

Turned out to be IC007. the deflection processor.  Apparently Sony used this same design (N3 chassis) in several of its own and re-branded monitors, and it was quite common for this IC to fail in that chassis and cause these symptoms. I found an NOS one for a reasonable price and found someone local who does SMD rework for a reasonable price as well.

Monitor is now happy, and so am I.

[Zebidee]

Good News!

I had a feeling it has the horz IC as it was a Sony. I've had techs tell me similar about Sony PVMs.

I recently remembered I have a Panasonic TV in an arcade cab that had symptoms like yours, but the solution was power supply related - had to replace a large blue ceramic disc cap near the huge resistor at the end of the B+ section. The blue ceramic cap had been pushed against the resistor's leg, and the insulation had been worn/melted away, thus the emerging problem. I replaced the ceramic cap with an NOS one, and couple of other aging electro caps, and the problems went away.

[buttersoft]

That's huge news, and certainly one to bookmark. Congrats on seeing it through, and here's hoping you get many years use out of it!

Now, i have a busted monitor sitting around somewhere i'm going to examine for this issue...