i have an old acoustic 150b. i gigged with it for a long time with no problem. i plugged it in the other day and it turns on but makes no noise. but if i let a string ring then power off, the sound comes on for a second then turns off. any suggestions?
You can round up a schematic. see the wikipedia page on "Acoustic Control Corporation"
I doubt the amp has a soft start, Or it may have a protect mode that is engaging and disconnecting as the power supply bleeds off.
Look inside for a relay.
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my amp only makes sound as it powers down 
