IBM 5154 Troubleshooting

[modem7]

I've acquired five 5154s

Quite a lot.

Does anyone elses do this on the screen when not connected to a computer?

As I am sure you are aware, expected is what is shown at [here].

I made a video of one, what do people think?

Vertical deflection problem.

Done a thorough visual inspection ?

I have fixed various (including 'weird') vertical deflection problems in the 5154 by replacing the TDA2653A chip, but there can be many causes.

Do you have an oscilloscope and the knowledge of how to use it? If so, do you have the SAMS Computerfacts document on the 5154 ?

Also I don't know if it makes any difference but I'm in Australia so the monitors are 240V.

No difference.

If you can deliver (and fetch) the problem monitors to the south eastern suburbs, I will freely look at them in my spare time.

[TRS-Ian]

Thanks Modem7, that gives me much to go on. Yes I have a scope and soldering rework station, and now with the Sams guide.

I've had a look and the 2653A (if that turns out to be the problem) is available locally and not for very much $.

I plugged in a 3rd one of these yesterday and while the filter caps blew one after the other pretty quickly, the clear white screen was observed this time, so I'm going to focus on that one first and come back to the other two with the obvious deflection probs later.

Cheers,

Ian.

[nztdm]

Anyone want to help +1 to the pile of repaired 5154s?

A friend recently won an auction for a small haul of IBM stuff, mostly faulty. Among them was a 5154 which they'd bee wanting for ages. I offered to repair as much of the IBM stuff as I could, including the 5154, and got myself a 5151 I wanted and a few other doodads in exchange.

This 5154 has had a lot of hours put in so far, and I am not too sure where to go on yet.

1) RIFA caps in PSU, and the commonly bad small caps had to be replaced for it to fire up.

2) the pots relating to sync and size were all wrong. I got that working for both Mode 1 and Mode 2.

3) someone else had already had a go it seems. The convergence was way off and one of the ring tabs was snapped off. I think they tried to adjust convergence without loosening the main ring. I have re-converged it the best I can. It is still imperfect around the edges. I don't know if that's normal for this monitor (it's still better than my 5153, but my 8513 is perfect). First time I've tried converging a CRT, and I spent a good few hours.

4) Nearly there I think. The problem now is that the image is wobbly on startup for a good few minutes. The wobble get less and less until it looks like a vibration (not seen on camera), until finally, the picture is solid. But after that, it still glitches occasionally, and one time, it even went complete out of focus for a moment before coming back.
This video shows all of that. The out-of-focus event is near the end.

I have replaced all the caps on the video board, and some of them on the main board. The remaining caps for the main board are on their way.
I have applied fresh solder to most of the joints and inspected the rest.
Someone said it may be the tripler. I have found a replacement, but the shipping cost is high, so I would rather rule other things out first.
The FBT has no part number, but that person said the tripler is far more likely to go than the FBT.

[nztdm]

To add on to my prior reply:
I have just finished replacing the rest of the electrolytic caps in the 5154.
This has solved the wobbly sync when cold. I still occasionally get the bursts of out-of-focus picture, especially when cold. Not sure what to check for next so I may try find a replacement tripler.

[TheDrip]

I identified a 'only when cold' issue on another system by spraying each component with an upside down can of canned air. Maybe not the best for an intermittent problem, but it sure identified the temperature sensitive part quickly.

[rittwage]

Bursts of out-of-focus *could* be the flyback. Any cracks/leaks or sounds near it?

[nztdm]

Bursts of out-of-focus *could* be the flyback. Any cracks/leaks or sounds near it?

I don't hear anything odd near the flyback.
The flyback and tripler are separate units on this, unlike most CRTs where they're combined.
I have cleaned the tube neckboard, socket, and fixed some suspicious solder joints there, to no effect.

According to a schematic (Sam's), there are separate horizontal output and high-voltage output transistors. Perhaps the high-voltage output circuit has a problem. I don't have the tools to probe that section however. I could check the power supply though.

Also, I noticed that even though the main wobbly sync issue is gone, there is still a slight one that persists. You can see it in my video here: https://photos.app.goo.gl/i1CeZRKESLTcXuPW9