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Hoffman Amps Forum image Author Topic: Bogen CHB14 Power Transformer Replacement  (Read 2118 times)

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Offline Ifudontlikebees

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Bogen CHB14 Power Transformer Replacement
« on: December 23, 2021, 03:43:40 am »
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!
« Last Edit: December 23, 2021, 02:36:24 pm by Ifudontlikebees »

Offline Latole

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Re: Bogen CHB14A Power Transformer Replacement
« Reply #1 on: December 23, 2021, 03:59:26 am »
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
« Last Edit: December 23, 2021, 04:07:24 am by Latole »

Offline sluckey

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Re: Bogen CHB14A Power Transformer Replacement
« Reply #2 on: December 23, 2021, 07:29:56 am »
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.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Latole

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Re: Bogen CHB14A Power Transformer Replacement
« Reply #3 on: December 23, 2021, 07:47:43 am »
Sluckey is right :


Offline Ifudontlikebees

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Re: Bogen CHB14A Power Transformer Replacement
« Reply #4 on: December 23, 2021, 02:35:28 pm »
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.

Offline Latole

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Re: Bogen CHB14A Power Transformer Replacement
« Reply #5 on: December 23, 2021, 02:39:54 pm »
, 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.

« Last Edit: December 23, 2021, 03:06:11 pm by Latole »

 


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