Dodgy MVS wiring.

PCB problems and fixes
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FriedGoat
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Dodgy MVS wiring.

Post by FriedGoat »

So my astro city came with an MVS 1 slot inside, whoever previously had the cab has hacked some of the strangest wiring into it.
I've managed to revert a lot of the hack jobs but this one on the MVS motherboard I have left for now as when I remove the wire it has no sound.

What the heck is this? And would it be the reason the cab crackles like a mofo for a second when I switch it on?

Image

Image

Its connected to the big capacitor from underneath.
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nem
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Re: Dodgy MVS wiring.

Post by nem »

That's ridiculous.

Looks like it goes to the negative leg of the cap, so some kind of grounding thing.

I would remove everything. Should be easy enough to spot what is stock wiring and what's not.
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Re: Dodgy MVS wiring.

Post by FriedGoat »

The problem is, if I remove the wire, I no longer have audio. The wire seems to be hacked onto the jamma audio wire, without it all sound stops. Could it be bypassing something faulty on the MVS board? Just trying to work out what the point of it is and how I can get audio if I remove it.
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Re: Dodgy MVS wiring.

Post by nem »

You don't have any other boards?

I guess there's something wrong with the audio output of the MVS motherboard, but I don't see any reason why you would want to keep it like that. Working MVS motherboards aren't very expensive.

Check the PSU for the connector pinout. You should have SP+ and SP- going from there to the jamma connector (SP+ goes to pin 10 parts side, SP- goes to pin 10 solder side). They're just straight wires, nothing in between.
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FriedGoat
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Re: Dodgy MVS wiring.

Post by FriedGoat »

Well, it seems sound + and sound - are connected to the pins you mention. The white cable seems to be spliced onto the sound +.

And I don’t really want to keep it like this, but if the sound works.... the question is what damage could this potentially cause.
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FriedGoat
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Re: Dodgy MVS wiring.

Post by FriedGoat »

Ok so get this. At further inspection of the board the trace from pin 10 has been removed all the way to the white line.
(this is not mine but the exact model i have, you can see the trace for pin 10).
https://retrogamingstuff.files.wordpres ... g_0939.jpg

I'm going to attempt to connect this white wire directly to the trace.
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Re: Dodgy MVS wiring.

Post by FriedGoat »

Image

Guess the only way to get sound is with the cable, i tried on the exposed area and sound is exactly the same as when attached to the back. Looks like I will need to buy a less messed up MVS board.
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Re: Dodgy MVS wiring.

Post by Sunder »

Well if you don't want it you can sen it to me, I'm always making CMVSes for friends.
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