help fix a broken PVM Olympus oev143

[MattyP]

Spoiler

hello, after a very long wait I finally had the opportunity to buy an Olympus oev143. It worked fine for the first day but on the second day it appears to have suffered a vertical collapse. I briefly turned it on to snap these two pics. I wont leave it on for more than a couple seconds as I looks like the bright white line from the squished menus could cause burn-in. I looked at the service bulletins and saw the part C584. according to the service bulletin, this is supposed to be changed from a 160v 2uF to a 160v 1uF capacitor in the event of a vertical collapse. this part is on the A board near the deflection area. I took the PVM apart and removed the C584 capacitor. I was dismayed to see that this had already been changed to a 160v 1uF capacitor. I tested it with a multimeter and found the capacitor was only a little off spec. putting in a new capacitor didnt make a difference after it was reassembled and turned on again. Im uncertain how to fix it. Can someone give me any tips? im hoping this is a one shot fix sort of problem and someone else knows how to fix it.. thats probably too optimistic huh?
https://imgur.com/OgpEIxG
R G B lines near top of display

https://imgur.com/G3aEXdN
the menus look squished


I cant figure out how the embed the picture

[jd213]

Did you see this thread?
viewtopic.php?hilit=sony%20vertical%20c ... &p=1526804

There's a couple other threads here on OEV PVMs, I'm guessing it's a bad IC, voltage regulator, or possibly a resistor.

edit: Might also need a recap, I believe the RGB lines in the picture like that are indicative of bad caps.

[MattyP]

Thanks I'm giving that thread a read. I might as well start taking it apart again. I'm not totally sure what im doing but want to avoid unnecessarily throwing parts at it. At least I've made the safety discharge tool and am now familiar with taking it apart.

[jd213]

From my limited experience, the vias and traces on boards in the OEVs can be easy to damage, so you might want to get a good desoldering gun and practice on other 2-sided boards.

Hopefully someone else with more experience can give you some advice on how to find bad components, but here's what I can suggest:

When you test resistors, they can sometimes be tested in-circuit, others just need 1 leg desoldered to get a proper reading.

A cheap Chinese component tester is probably good enough for testing most other passive components out of circuit, but you'll need something more expensive for reliable readings.

As you may have seen on my thread about my OEV 143, I had one with a bad film cap, so there's many things that can go wrong.

[MattyP]

I am pretty good at soldering and have had a decent amount of practice but less so on PCBs. I just did one of those console 5 parts kit on a atari 2600 though. Oh man that thing was delicate. I lifted a few pads on the vias but the atari survived the ordeal.


It's the electronics diagnosis part the has me a little more worried than the soldering work. The block diagrams are a little headache inducing.. for now, I have a pretty decent soldering iron. It's a hakko fx-888 but I've had it for about 17 years. I'm probably going to upgrade to
an AXIUN T420D eventually . This is an imitation JBC soldering unit but I watched a disassembly video of the T420D.. it has a "free floating" torodial transformer power supply that doesn't output any voltages at the tip of the iron. it's good for working around delicate ICs.

I've been slowly upgrading my tools over time. There's a lot of items I'll probably order. For the time being I have enough stuff to get started

[matt]

That's almost certainly a bad transistor, diode, or resistor. The center of the picture is smashed together, while the top and bottom are stretched. If it was the boost capacitor, either the whole picture would be compressed or you'd be seeing foldover. IIRC the 14M2 doesn't have a discrete vertical deflection IC; the vertical circuit contains a number of transistors and passive components. So there are a number of parts that could be at fault.

Another clue is that it happened suddenly. Capacitor failures typically get worse gradually over time, while a defective IC (or another component like a diode or resistor) failing will cause a rapid change that's immediately noticeable.

For vertical deflection issues like this, the single most useful tool you can get is an oscilloscope. That will let you see what the waveform itself, how it translates to the picture on screen, and where in the circuit it's getting corrupted. You don't need anything fancy (it's just a 60 Hz 60 vpp signal) and nowadays there are cheap handheld units that will do the job fine. In this case, it would be invaluable as you can trace the signal backwards from the yoke and see where it falls apart.

[MattyP]

Thanks for the information. I don't have an oscilloscope.. If I'm unable to repair it I may consider sending it out. For now I'm having difficulty finding spare time to work on it. But summer is here
I'll have some spare time soon.

I did order a peak ESR70. I'm hoping to isolate a broken part with that tool.