Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Ifudontlikebees on December 23, 2021, 03:43:40 am
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Hey guys! I recently acquired a bogen chb14a that I wanted to convert to a useable guitar amp as is. I alligator clipped in a 1/4 inch jack for the speakers and guitar input and plugged it all in. I got no sound and noticed a bright flash of light from the 6V4 tube and then smelled and saw smoke coming from the power transformer. Not really sure how it fried but it happened! Would anyone know a suitable new replacement for the power transformer? I’d like to get this amp up and running again so I can start working on it. Thanks guys!
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You don't replace a transformer just on these simple and insufficient observations.
There is a cause that made the transformer smoke. It must be found and repaired otherwise a new transformer will smoke too.
IMO there is a short somewhere after the 6V4 rectifier.
Use bulb light limiter to test.
Concerning the current transformer, you have to measure the voltages with all its wires disconnected. You will see if it is still good and it is very possible
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The Bogen CHB14A uses a SS voltage doubler rectifier, not a 6V4 tube. What you describe is probably a CHB14, which does use a 6V4.
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Sluckey is right :
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Ah my mistake this is the CHB14 becauses it does have the 6V4. I'm also realizing that this amp seems to never had a fuse which is weird, nowhere to be found and no holes in the chassis. I apologize for any newbie questions or remarks too, I am new to working on tube amps but have been extensively researching safety precautions and studying schematics to get a good understanding. So I guess I'll start off by building a lightbulb limiter and checking the caps. Upon further inspection I noticed that the .01 ceramic disk capacitors that are on the two 6GW8 tubes are bubbling. Obviously that's not good and they should be replaced, but would that cause the PT to smoke? Thank you all to have responded! Wishing you happy holidays.
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, but would that cause the PT to smoke? Thank you all to have responded! Wishing you happy holidays.
See first answer please.
There is a short after the PT or after le rectifier tube.
Tube rectifier, Power tubes, Output transformer , filter caps to name a few.