Pac Hum Bar

FrizzleFried

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Anyone have any idea why one Pac PCB would produce a hum bar while another runs fine? My understanding of the hum bar issue is that it's likely a connector or fuse issue (ie: cabinet hardware that remains the same between these two boards).
 
Less common, but it happens....the caps in the power supply section of a Pac can (also) cause a hum bar. Alternately, the edge connector could be marginal and just "bite" one board better than the other (this assumes the edge connector is original).

Edward
 
Bad regulator on the pac board can be a problem too.

Check the soldering at those large diodes.

Recap the Pac board (axial leads! ) .
 
And check the diodes for reverse leakage. You might have one on the way out.
 
Humbar is usually an a/c issue or power supply. Bad fuse holder/capacitors/connectors/

You know arcadeshop has a pac/mrs pac hum bar repair kit. I wonder what it includes?

Dave
 
Humbar is usually an a/c issue or power supply. Bad fuse holder/capacitors/connectors/

You know arcadeshop has a pac/mrs pac hum bar repair kit. I wonder what it includes?

Dave

Hum by definition is AC in a DC circuit. Doesn't seem fuses could cause it, but definitely on the right track with the power supply.
 
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