palomar 300a keeps blowing fuse when turned on

[adgitater]

It keeps blowing fuse in the back of amp, the power supply buzzes before it blows. any idea what is happening?

[Fixer]

I would check for a shorted rectifier in the power supply first. Other possibilities are a shorted power transformer and filter caps.


Alan

[721HACKSAW]

Safety first, before you do anything inside make sure those capacitors are dis-charged!
Make note of the tube placements, then remove them from their sockets, attempt to power up the unit then..
If the fuse holds you have a bad tube, which isn't uncommon for an old rig like that. Power down the unit and reinsert one tube at a time until you find the bad one. Remember, safety first...
Good luck and enjoy.

[tulmkr]

I have had a few of those boxes, and one of the weak points is the rectifier board. A shorted rectifier will blow the fuse right away. Put the amp on standby, and set it to low, turn it on, see if it pops it. If it doesnt blow the fuse, turn it to operate with the amp on low, that takes the driver tubes out of operation. If it doesnt pop the fuse, you have a bad driver tube, or tubes (there are two driver tubes in that amp). If it pops, you have bad rectifiers, or a bad power supply. Also look for bad (bulging, or leaking) caps. Replace any that are leaking or show signs of bulges.