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neo geo mvs 2 slot sound problem

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monkeymagic View Drop Down
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    Posted: 07 Nov 2018 at 6:20pm
hello is there anyone on here who offers a repair service for  neo geo boards i have one and it needs re capping the sound is breaking up cheers 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TheDaddy Quote  Post ReplyReply Direct Link To This Post Posted: 07 Nov 2018 at 6:45pm
Hi , are you sure its just caps ?? There is folk on here who repair. I repair but to busy at the minute.

Dave.
AKA Wonderboy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thegreathopper Quote  Post ReplyReply Direct Link To This Post Posted: 07 Nov 2018 at 7:05pm
The sliding volume pots often go on these, have you tried the headphone socket to see if that is also cutting out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 07 Nov 2018 at 11:50pm
There is a lot that can make audio go wrong sadly. Sometimes yes it's caps and others the volume pot.
However it can also be due to track corrosion around the audio z80 cpu and YM chips (helpfully very close to leaky batteries).
Probably best to get a video and post it up showing what the audio does over time.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote monkeymagic Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 2018 at 4:37pm
hello thanks for the help and reply's everyone iv tried the head phone sockets and it is the same i do not think it is a problem with the chips on the board the sound is working i would just describe it as low quality sound like a badly tunes radio iv had this same problem a few years ago on a data east pinball and it was the caps  when you say your busy Dave its not urgent at the moment i can wait and send you a message in a few weeks and see if your still busy cheers terry 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pulstar Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 2018 at 4:44pm
It could be the caps, but it could also be the OP-AMP going bad. One of mine had fuzzy audio years ago and after changing the caps it was no different. Turned out to be the OP-AMP. At least I don't have to worry about caps going bad for a years now though.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 2018 at 7:04pm
I have one that starts fine, but begins to go fuzzy and clicks once it's been powered on for a while. That strikes me as being a cap issue, or a dryjoint heating up over time somewhere.

Another that's on the repair bench previously had a z80 error from track corrosion. That was fixed, but now it's started clicking and the audio is sometimes corrupted / acts oddly. Definitely not a cap thing there.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ace` Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 2018 at 7:06pm
It usually is bad caps on multi slots, single slots don't seem to have the issue. I remember recapping a 4 slot a year or two ago and about 70% of them were way out of spec.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote monkeymagic Quote  Post ReplyReply Direct Link To This Post Posted: 09 Nov 2018 at 4:27pm
the single slots are mono i think  maybe that is why the caps dont go wrong there not as complex 
thanks for the help everyone a member has said they can help fix it so it looks like it will be sorted cheers 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 09 Nov 2018 at 5:39pm
All boards process the audio in stereo, just to maintain jamma compatibility the one slots downmix it to mono for output. It's possible to remove a couple of small resistors and tap out the stereo audio from points on the board. A small PCB with power + capacitors is needed to boost the signal before the final stereo output. JNX have a bunch of how-to's for the various versions.
However because they are normally modded for consolation, nobody has done a solution that maintains the mono audio out on the jamma edge.
I'm pondering a board with a switch that maintains that compatibility - effectively creating a daughterboard with the MV1-FS stereo / mono switch on it, for MV1A / MV1F / MV1FZ mobos.


WTD: OutrunDLX, Rainbow Islands, Rolling Thunder, Wonderboy pcb
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