Centipede audio

shuyge

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So apparently I've screwed up.

I took a working (I don't know how) Centipede and I've lost audio.

When I got the machine home, I discovered that R29 on the ARII board was blown. I also had some burned pins on the board. I know that this is a common problem.

So I replaced big blue, recapped the AR2 with a kit from ArcadeShop. I also repaired the burned pins on the edge of the board with 1183 tape.

I know that I need to replace the connector, I just haven't gotten to that yet.

So anyways, as I was going through powering up the system, I plugged J8 of the ARII board in while it was powered up. I don't think I had the board plugged in, but I heard a snap.

I get the rest of it going, and now I have no sound.

I currently own a decent digital and analog multi-meters and a logic probe.

Can I use these tools to track down where the problem is?

Can I use the multi-meter on AC mode to track where I have audio signal?
Can I use the logic probe somehow to track it?

I haven't really used the logic probe before so I'm a real rookie on that front.

While I do want and plan to buy a scope, it isn't in the cards at this moment because I blew all my current funds and my wife's patience on a Galaga already this week.

Any help would be appreciated.

Thanks,
Stan
 
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First step is to check all of your voltages, on the AR. +5V, +12V, and -5V.

Next, try to figure out what snapped. Visually inspect every component closely. If you think you know the general area it came from, start there first. If you can figure out what blew, that will be the biggest clue in determining what to do next. If it happened when you plugged the speaker output connection in, it could be one of the two TDA2002 amps on the AR. If that's the case, you can replace it and that may fix it.

Sometimes you can use your nose as well, to sniff out a burned component. (Weird, but true.)
 
First step is to check all of your voltages, on the AR. +5V, +12V, and -5V.

Next, try to figure out what snapped. Visually inspect every component closely. If you think you know the general area it came from, start there first. If you can figure out what blew, that will be the biggest clue in determining what to do next. If it happened when you plugged the speaker output connection in, it could be one of the two TDA2002 amps on the AR. If that's the case, you can replace it and that may fix it.

Sometimes you can use your nose as well, to sniff out a burned component. (Weird, but true.)

Andrew,

I will definitely check my voltages when I get home tonight.
Assuming that my voltages are all fine, can I use the tools that I have to actually follow the audio signal to find where it stops?

Does the test mode have any setting where it emits a continuous tone or something that I can follow through the audio circuit?

I'm not sure that I can pick up any TDA2002 amps around town and certainly don't have any laying around.
 
There are only two real components in the audio circuit. (3 if you include the Pokey.) there is an LM324 amp on the game board, and the TDA2002's on the AR, which do the power amplification.

It's very likely one of the TDA's. They're obsolete, but you can get them on eBay. You can also use TDA2003's, which are a drop in, beefier substitute.
 
Andrew,

I will definitely check my voltages when I get home tonight.
Assuming that my voltages are all fine, can I use the tools that I have to actually follow the audio signal to find where it stops?

Does the test mode have any setting where it emits a continuous tone or something that I can follow through the audio circuit?

I'm not sure that I can pick up any TDA2002 amps around town and certainly don't have any laying around.


i stock NOS ones and any other part you may need on that ar board including cap kits and rebuild kits.
 
Thanks for the help guys.

I forgot that I had been looking at the marquee and that the speaker was part of the same connector. They work better when they're plugged in.
 
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