Galaga buzz

KazooBR

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I've seen a lot of threads about Galaga buzzing but never seen anything more than recommendation to cap the sound section of the PCB or check the marquee bulb. I've disconnected the marquee light altogether and recapped the PCB with a Bob Roberts kit. This game does have an arcadeshop switcher installed before I got it.

Here is a video of the noise:
http://www.youtube.com/watch?v=tcV_y43ztrc

Any other ideas on what I could try?
 
That sounds like an open ground somewhere... Bad trace or pulled plated thru hole... Could also be a bad cap that hasn't been replaced yet...
 
asteroids was renowned for the buzzing,i know mine did when i bought it and i mean real bad.there were lots of suggestions on how to solve it,some things worked for others and not for some,i first tried sappping the cap on the transformer,no good,i then replaced the edge connector and it went away.
:)
 
I'll tackle the grounds first and then consider the edge connector. I appreciate the input and will post back results!
 
I have this same issue. I played with the edge connector and swear it went quiet at one point,so I cleaned the contacts both on board and the connector with no improvement. Since then the buzz has been consistent. I also capped the sound circuit and checked grounds. Is yours fixed?
 
It going quiet at one point is probably due to your fingers adding capacitance where it was needed. Amps on arcade boards always were cheap and nasty, you only notice as you have a cab somewhere quiet, in the din of the arcade there was no point in them spending money making it hifi.

If I were you I would google the amp chip and find the datasheet, they always contain the recommended circuit, which will show the input caps on the 12V rail. You should check your board has them, and also check the ESR of all the caps in the amp section. You will need an ESR meter to do this but you may find the old input caps are shot. Electrolytics do no like being warm, and being in close proximity to the amp heatsink is not the best environment for them.
 
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Hmmm, so it shouldn't be an issue to put a large cap inline to see if that'll level out the buzz wave? Wonder how many farads I should shoot for? Just make sure the voltage is higher than 12v I spose.
 
put a large cap inline. got rid of the buzz, but no sound haha. Did I missinterpret this? Wonder if one of those small inline transformer looking filters you see on car stereo harnesses is a better route?
 
I have this same issue. I played with the edge connector and swear it went quiet at one point,so I cleaned the contacts both on board and the connector with no improvement. Since then the buzz has been consistent. I also capped the sound circuit and checked grounds. Is yours fixed?


No - I haven't gotten around to checking it yet.
 
I'd just swap the power supply out with another one and see if that takes away the buzzing. I've had tons of games that the power supply caused problems.

Just for giggles take the coin door bulbs out and see if that changes it.
 
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