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

Page 1/2
| 2

By cr4zymanz0r

Rookie (17)

cr4zymanz0r's picture

07-09-2017, 05:41

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?

Login or register to post comments

By Alexey

Guardian (3375)

Alexey's picture

07-09-2017, 11:50

Looks like MSX successfully boots and starts the game (Nemesis 2?). The problem is with synchronization. Please check the components that form CSYNC signal. If I remember correctly there should be transistors and electrolytic capacitors in that circuit that could be faulty. Capacitors could have leaked too.

Which model is this btw?

By cr4zymanz0r

Rookie (17)

cr4zymanz0r's picture

07-09-2017, 15:56

It's a Sony HB-F1XDJ.
I did find some info about the caps going bad on these after posting. Sure enough after I removed the surface mount caps on the hybrid board that the video encoder is on, there was leakage underneath. Traces appear to be intact but the solder pads are pretty dirty. I'll have to clean those up and order some caps.

I haven't seen anything about the transistors going bad though. Do you have anymore info on that?

By meits

Scribe (6498)

meits's picture

07-09-2017, 17:29

They're notorious for their caps on this daughterboard (forgot the real name). Mine is being redone as well. All for preservation. Good luck on yours Smile

By Alexey

Guardian (3375)

Alexey's picture

07-09-2017, 17:39

Transistors are rarely affected. Usually the evil leaks from the caps. Wink

I would recommend to replace the electrolytes with tantalum capacitors.

By cr4zymanz0r

Rookie (17)

cr4zymanz0r's picture

08-09-2017, 01:44

Is it recommended to replace any/all the through-hole electrolytic capacitors on the main board, or do I only have to worry about the surface mount ones on the hybrid/video/daughter/whatever board?

By meits

Scribe (6498)

meits's picture

08-09-2017, 01:47

The ones on the daughterboard are notorious suiciders...

By cr4zymanz0r

Rookie (17)

cr4zymanz0r's picture

08-09-2017, 03:16

Well, turns out I had some spare capacitors that were the right spec for the 3 on the hybrid board.....but that wasn't good enough. It's "better" now where I can see the image sometimes, but still completely unplayable.

By cr4zymanz0r

Rookie (17)

cr4zymanz0r's picture

08-09-2017, 05:11

Here's a video of what it's doing after replacing the caps on the hybrid board: https://youtu.be/wj7mjk0ty_E

By Jipe

Paragon (1551)

Jipe's picture

08-09-2017, 11:46

resembles the sound mixed to the video
check the sold on the mini-card

By Alexey

Guardian (3375)

Alexey's picture

08-09-2017, 15:33

Conductive electrolyte could have leaked around and under the board. I would wash all around with white spirit.

Page 1/2
| 2