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FDP Forum / Fender Amps: Vintage (before 1985) / Took out a diode.



Apr 17th, 2017 12:32 PM   Edit   Profile  


I'm working on a Magnatone M6.

Started off pretty routine. Replaced the can cap and a dropping resistor on the rail to get rid of some hum.

A ceramic cap had broken off in the oscillator section. Replaced it and the vibrato came back.

Pulled out the death cap and added a grounded cord.

Anyway I'm checking voltages and accidentally grounded a plate off one of the power tubes. A big spark happens and a circuit breaker goes off.

After this the amp keeps blowing fuses immediately after turning it on. Bad tube? Replaced them all to no avail. Some sort of short in the socket? Nope. At this point I ran out of fuses.

Checking resistance to ground along the railI finally found that of the rectifying diodes went bad from the surge. I don't have any so now I have to wait for one in the mail...along with a bunch of fuses.

Sucks because I wanted to play it this weekend.

Contributing Member

So. Cal. USA

Apr 17th, 2017 01:24 PM   Edit   Profile  

Dang, it does happen however. No matter how careful I am every once in while the smoke come out of something.

I've begun using alligator clip on my meter of late. Clip on then power up. Shut down and repeat. It takes longer but as you know just one little shake of the hand and.....


Cincinnati, USA

Apr 18th, 2017 06:27 AM   Edit   Profile  

Hopefully it won't happen again but in the future you can jumper a light bulb across the fuse holder and it will indicate a short without burning through your fuse inventory. I had to do this to fix my pinball machine.

This is basically a stripped down dim bulb tester without the outlet.

Contributing Member

The spotlight

looks like a prison break
Apr 30th, 2017 03:18 PM   Edit   Profile  

Every time I walk into the shop, my dim bulb tester goes DING DING DING!

I hate that :o)

FDP Forum / Fender Amps: Vintage (before 1985) / Took out a diode.

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