Neo Geo AES SYNC HELP NEEDED

[BTD]

Classic case of "if it ain't broke, fix it until it is".

My AES was working fine. Decided I needed to replace the caps because... reasons.

Replaced 4 caps by the video chip. 2 10uf, 1 100uf and one 4.7uf.

Now of course, the video is garbled. Did I break the video chip?

Note, this isn't my first solder job or anything like that.

I have checked traces, checked PSU (it is 5v POW), etc.

I'm using scart to rgb+s bnc breakout cables into BVM. Doesn't work on OSSC either.

Board revision 3-4.

[Bratwurst]

Check and measure the composite and c-sync outputs of the CXA video encoder chip as a starter.

[BTD]

Check and measure the composite and c-sync outputs of the CXA video encoder chip as a starter.

Pardon my ignorance, but what exactly am I looking for?

[Bratwurst]

An oscilloscope would be the best tool here, on the pins of the chip you want to see .7vpp on the composite output and .7vpp or TTL which is 5vpp(??) for c-sync. I don't have a Neo Geo AES at my disposal to check what c-sync should be at exactly.

Possible that a vias for one of the caps cracked at the very start of the trace when you did your capacitor replacement, you could check continuity with a multimeter from each leg of the caps you replaced to the other end of the trace leading from that particular leg.

Is composite output working, have you tested that on another tv?

[BTD]

An oscilloscope would be the best tool here, on the pins of the chip you want to see .7vpp on the composite output and .7vpp or TTL which is 5vpp(??) for c-sync. I don't have a Neo Geo AES at my disposal to check what c-sync should be at exactly.

Possible that a vias for one of the caps cracked at the very start of the trace when you did your capacitor replacement, you could check continuity with a multimeter from each leg of the caps you replaced to the other end of the trace leading from that particular leg.

Is composite output working, have you tested that on another tv?

Firstly, thank you for the help thus far. It is appreciated.

Let me jump to composite... it works just fine. Dunno why I didn't think to try that.

All continuity has been checked. No issues there.

My oscilloscope knowledge is limited (really only used for audio repair). I do have a small one I could test.

I have been using this schematic to try and troubleshoot. https://wiki.neogeodev.org/images/c/ca/ ... ge-007.jpg

So I know it is outputing composite video signal fine. My understanding is that the sync in the composite out is the same as RGB + Sync just also mixed in with the video signal.

Now, while I checked continuity from the chip to other components throughout the board. I probably didn't check from the Sync out all the way to pin 7 of the DIN connector.

That's where I am.

[Bratwurst]

Firstly, thank you for the help thus far. It is appreciated.

Let me jump to composite... it works just fine. Dunno why I didn't think to try that.

All continuity has been checked. No issues there.

My oscilloscope knowledge is limited (really only used for audio repair). I do have a small one I could test.

I have been using this schematic to try and troubleshoot. https://wiki.neogeodev.org/images/c/ca/ ... ge-007.jpg

So I know it is outputing composite video signal fine. My understanding is that the sync in the composite out is the same as RGB + Sync just also mixed in with the video signal.

Now, while I checked continuity from the chip to other components throughout the board. I probably didn't check from the Sync out all the way to pin 7 of the DIN connector.

That's where I am.

Good composite video means the CXA encoder chip is most likely working. Check continuity from sync to the DIN connector.

Could be you got a bad cap, may need to replace it again.

Also check your cable and verify the sync line is not broken.

[BTD]

Firstly, thank you for the help thus far. It is appreciated.

Let me jump to composite... it works just fine. Dunno why I didn't think to try that.

All continuity has been checked. No issues there.

My oscilloscope knowledge is limited (really only used for audio repair). I do have a small one I could test.

I have been using this schematic to try and troubleshoot. https://wiki.neogeodev.org/images/c/ca/ ... ge-007.jpg

I was thinking the same on the chip. If it can downgrade RGB to composite, the pass through shouldn't be affected.

I've tried two different sets of cables. No luck. I'm wondering if the sync pin of the DIN socket has cold solder. I'll check that next after the continuity.

Never had a bad nichicon cap but I guess there's a chance. I'll pull them and their them on the tester.
So I know it is outputing composite video signal fine. My understanding is that the sync in the composite out is the same as RGB + Sync just also mixed in with the video signal.

Now, while I checked continuity from the chip to other components throughout the board. I probably didn't check from the Sync out all the way to pin 7 of the DIN connector.

That's where I am.

Good composite video means the CXA encoder chip is most likely working. Check continuity from sync to the DIN connector.

Could be you got a bad cap, may need to replace it again.

Also check your cable and verify the sync line is not broken.

Ok. So went ahead and changed the caps around video output. It's working now!


But some bad news. I 100% think it was fine before. EVIDENTLY, my bvm sync settings got all kinds of screwed up. Which happened EXACTLY after I changed those first caps out. At the same time, my new to me OSSC was not set to RGB. So both outputs looked wonky.

Sigh. I feel dumb. Ah well. Thanks for the help anyway. I will now go hide in shame.