Where can I get the scematic for the Veco 21 STC voltage control circuit board?
try mailing the manufacturer
hot transistors are usually shorted out, or driving a short!!
a multimeter across the 3 transistor legs (TO-3 transistors have 2 legs & the case which is the 3rd leg) will reveal if they're dead (remove the transistors first as the circuit may give a false reading) - if you get a zero ohms reading between any of the legs it's dead - don't forget to check the smaller driver transistors too,, as a dead main transistor will kill its smaller driver transistor
speakers are marked,, usually 4 ohms or 8, though sometimes 16 ohms - use a multimeter to ensure you have something very close to these values according to the label on the speaker box & measure from the wires at the point where they connect to the amp
power the unit without any speakers or speaker wires connected,, if the transistors still get hot, you're very likely looking at bad transistors
Feb 21, 2015 |
Audio Players & Recorders