Neo Geo Speaker Pop

nerdygrrl

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I picked up an empty Neo cab from a friend. He had switched out the old box style PS for a switcher. I noticed that when I power it on, the speakers make a pop sound. I thought little of it until I plugged the board in and noticed a split second of scrambled graphics when powered on, I tried a second board and it did the same thing.

I tested my PS and it is putting out the regular volts, but I am guessing that split second of flipping the switch is sending a power surge. Does that make sense? I am going to go through and recheck all of my grounds, and I guess I should replace the switch. Is there anything else I should check?

I can't tell you how much I am looking forward to this as the Koam cabs are so easy to work on with their in tact back panels and all. It took me close to two hours to get the coin door of because of limited mobility.

I guess I could remove the monitor, break out my rock climbing gear, affix a pulley to my ceiling and lower myself down.
 
Could simply be bad caps in the audio section of the board.

The Neo Geo uses 2 470uf @16v caps in the outputs. You'll find them in-line with the JAMMA edge connector. They are used as DC blocking capacitors to keep the DC component output from the audio amplifier chip off the speakers.

Replace them and see what happens.

A split second of scrambled graphics is normal... The Neo Geo runs through self tests at boot time and the screen will do some strange looking, but regular things during those.
 
Channel, thanks. My Taito F3 did the same thing in the beginning. Speaker pop/graphics glitch and all.

On a side not the sound caps finally went in my Geo. I ain't got no sound now.
 
Bumping this. Even with a different Jamma board in there the speakers pop. None of my other games do this.

What should I be looking for?
 
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