Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: LooseChange on February 04, 2011, 11:21:20 am
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See the attached schematic.
The fuse blows only when the footswitch is connected.
Trial and error could blow lots of fuses.
What might be the problem??
Thank you!
>>>>I updated the schematic and attached to a reply below.
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Somehow I'm not finding the footsw on the portion of the schematic posted. But, meanwhile, maybe use a circuit breaker, instead of a fuse, until the problem is resolved.
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The foot switch circuit is the circuit just the the lower right of the bridge rectifier. It says "6 PIN DIN" at the top of the connector. Don't have a circuit breaker device. Thanks!
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Don't have a circuit breaker device.
Do you have a light bulb current limiter?
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Do you have a light bulb current limiter?
Yes. Do you think that will work and actually give me some visual feedback? The fuse just protects one small part (27v) of the circuit.
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Oh, sorry.....thought it was blowning the mains.......no, that won't help.
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Here is the schematic with the Foot Switch circuit in the red box.
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lamp limiter will likely still pop fuse - ckt is limited to <30 watts.
with S7 norm/bypass open or closed? if either way there is likely a short in the cable.
look for a short between pin 3 and the shield pin 5 otherwise i'd suspect C33-37 or CR3-5, but that just doesn't seem possible - there are 470 ohm Rs in series with each relay ckt. so the most current that would flow if there were a short behind R54,55, or 56 would be 27V/470R or ~60ma hardly seem enough to blow a 1A fuse. look for cable/connector problem.
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Does it work - switches - without the footswitch? I mean switching thru pannel switches?
Maybe C48 went south?
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I didnt see this thread until now. Let me go look at that schematic. I have worked on a lot of those peavey amps. I made this circuit breaker 5 years ago or so. Fuses are too expensive to go through them until you find a problem
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I made this circuit breaker 5 years ago or so. Fuses are too expensive to go through them until you find a problem
plexi, whats the part #/ spec's on it?
Thanks, Brad :smiley:
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The parts in my red square are all i can see in the circuit that could cause that fuse to pop. I have heard a pop when switching using the footswitch before and changing those caps was the cure for me
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I made this circuit breaker 5 years ago or so. Fuses are too expensive to go through them until you find a problem
plexi, whats the part #/ spec's on it?
Thanks, Brad :smiley:
There is no part number on this one. I got it at my local parts house here 4 years before they closed up
There was a box of about 50 of them. I knew then i should have bought at least 3 of them but i was in a hurry as usual
It was one of those 75 year old electronics part houses that had everything from tubes, testers to scopes and speakers,cloth wiring you name it
What a bummer it is that they closed up. You can get a small breaker like this a from Newark or Mouser im sure