Sony MSX2+ suddenly has bad video (acts like no sync)

[cr4zymanz0r]

So here's what my MSX is doing https://youtu.be/cKYXDu1Yew4

I haven't used it much in a while, but when I had been testing various systems with the OSSC I noticed the MSX was acting up some where colors were heavily bleeding to the right and wiggling the cable (maybe by coincidence) seemed to help. I thought maybe my RGB cable was flaky and I'd take a look at it when I had time. I turned it on a few weeks later and after a few minutes of a stable picture it got stuck doing similar to what you see in the youtube video.

Tonight I took out my RGB cable (actually a RGB RCA breakout box) to verify all my connections and soldering and everything looked fine. I hooked everything back up and it worked great for maybe a whole minute or two, then started acting the same as if there was no sync. Even If I just use composite video output from the RCA jack built into the MSX it's the same result except black and white.

It appears to have a Sony CXA1145 video encoder and I verified it's getting 5v. I also tapped composite video straight off the encoder and ran through a 220uF cap for testing but it didn't help. I'm pretty confused since it's barely been used in the past 2 or 3 years and has been sitting in the same spot undisturbed. Got any good troubleshooting ideas?

[ApolloBoy]

Have you recapped it yet? The Sony MSX2+ machines are notorious for leaky caps (especially the SMD caps on the hybrid board) and can cause weird video issues.

[cr4zymanz0r]

Have you recapped it yet? The Sony MSX2+ machines are notorious for leaky caps (especially the SMD caps on the hybrid board) and can cause weird video issues.

I haven't, but all the caps and areas around them look fine visually.
1.) Do you have any sources about these having caps issues? When I tried looking around I couldn't find much of anything about MSX video/cap troubleshooting.
2.) Also, by hybrid board do you mean little daughter-ish PCB that the Sony CXA1145 is on?
3.) Are there any places that sell cap kits for these, or am I just going to have to take inventory of the caps myself and order from Mouser or Digikey?

[ApolloBoy]

1.) Do you have any sources about these having caps issues? When I tried looking around I couldn't find much of anything about MSX video/cap troubleshooting.

Mostly from personal experience, I have an HB-F1XDJ that I've done a partial recap on, and I also did a full recap on another XDJ for someone years ago. In both cases I found that all the SMD caps had leaked and in the case of the one I was sent, my customer complained of having video problems and doing the recap helped fix that (in addition to fixing loose solder joints on the AV jacks). I even found regular leaded caps near the audio section of the motherboard that had leaked. This is also a well-documented problem with a few MSX2/2+ machines, here's a thread on it: https://www.msx.org/forum/msx-talk/hard ... ghterboard

2.) Also, by hybrid board do you mean little daughter-ish PCB that the Sony CXA1145 is on?

Yes, that's the technical term for it.

3.) Are there any places that sell cap kits for these, or am I just going to have to take inventory of the caps myself and order from Mouser or Digikey?

AFAIK nobody I know sells a cap kit, but they're all common values so it should be cheap to order the necessary caps. Watch out for the big filter cap near the power transformer since anything that's even the slightest bit larger won't fit inside the case.

[cr4zymanz0r]

Sure enough, when I removed those surface mount caps there was obviously leakage underneath. The traces look to be intact, but the solder pads on the bigger one are pretty dirty looking. I'll have to find a good way to clean it up so the solder will stick then order some caps.

[cr4zymanz0r]

Turns out I had some spare compatible caps for that hybrid board. Replace those caps and now things are "improved", but still horrible https://youtu.be/wj7mjk0ty_E

I don't know if my only option now is to blindly replace all the caps on the main board (which looks to be quite a few).

[ApolloBoy]

I would try recapping the rest of the system, certainly wouldn't hurt. Have you also tried reflowing the solder joints on the RCA jacks and RGB connector?

[cr4zymanz0r]

Well I did get it working again

I'm not entirely sure what particular thing fixed since I went back and did a few things:
* Cleaned the whole top of the hybrid board with rubbing alcohol and q-tips (rather than just the area around the faulty caps when I was replacing them)
* Reflowed and added new solder to:
- The hybrid board's pins on the top and bottom of the board
- Some of the input pins on the CXA1145 video encoder (didn't think I could do all of them without bridging something
- AV connectors
- VDP chip

After that I tested again and it was working fine. I then put it all the way back together to play some Knightmare and Nemesis 3 on a 55" HDTV via the OSSC