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Peavey Bandit 65 transformer

Started by mr.death, May 17, 2024, 05:31:22 PM

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mr.death

Hi, Recently I was given an old peavey bandit 65 amp with issues. I replaced the old electrolytics and in the process some solder dripped across the board bridging some traces. I turned the amp on not knowing and fried the transformer as a result. I need a replacement transformer but am having a hard time finding one thats not bloody expensive. What criteria needs to be met when looking for a new transformer? Can I buy not peavey branded, generic? The part number for the fried part is 70518713.
Thanks


mr.death

Yeah, expensive. Looking to do this on the cheap. Makes no sense to add a hundred dollar part to a 50 dollar amp.

g1

The value of the amp has nothing to do with what parts cost.
If you can get another bandit 65 for 50 bucks, buy it and use it for parts.  You probably won't find an adequate transformer for that price.
Sorry if that sounds harsh, but that is the reality of parts costs.

You need a power transformer that puts out 60V center-tapped (30-0-30) good for at least 120VA.  If it's not the exact peavey unit, you will have to drill and cut to make it physically fit the chassis.

DrGonz78

What method did you use to make the conclusion that the transformer is shorted?
"A person who never made a mistake never tried anything new." -Albert Einstein

DrGonz78

#5
I mean from the description of what caused a failure of the amp we have little to go on. What is the status of the main transistors? We have no idea what traces you bridged. With so little information I personally can't say go buy a transformer. With more information then I might have more of an answer.
"A person who never made a mistake never tried anything new." -Albert Einstein

Tassieviking

It would be better if you added your location to your personal info, there have been times when someone had one and was happy to send it if the recipient paid the postage.
I remember one time it turned out they lived in the same town so there was no need to send it in the mail.
There are no stupid questions.
There are only stupid mistakes.

mr.death

Quote from: DrGonz78 on May 19, 2024, 12:19:47 AMWhat method did you use to make the conclusion that the transformer is shorted?
I watched a dlab vid. He shows how to check the transformer. I did his test and it failed. Also when I turned the amp on I could hear the transformer frying, bubling sound. Its toast.

mr.death

Located in Toronto Canada. Thanks thus far...

DrGonz78

Quote from: mr.death on May 22, 2024, 04:11:09 PM
Quote from: DrGonz78 on May 19, 2024, 12:19:47 AMWhat method did you use to make the conclusion that the transformer is shorted?
I watched a dlab vid. He shows how to check the transformer. I did his test and it failed. Also when I turned the amp on I could hear the transformer frying, bubling sound. Its toast.

Okay just had to ask or we might have let someone trash a power transformer. I like D-Lab a lot and he is a solid provider of good services. I never heard a bad transformer make bubbling noises. I mean I have heard a buzzing sound from old worn out transformers. But most bad transformers and we're talking fuses blowing when turned on.
"A person who never made a mistake never tried anything new." -Albert Einstein

mr.death

Quote from: g1 on May 18, 2024, 02:25:27 PMYou need a power transformer that puts out 60V center-tapped (30-0-30) good for at least 120VA.  If it's not the exact peavey unit, you will have to drill and cut to make it physically fit the chassis.
Im looking at the schematic... looks like it says 42.8V+, 42.8- coming out of the transformer after the diodes. Then goes through a pair of resistors down to 15V+, 15V-. Dont I need a transformer that is 42.8-0-42.8? Im not good with transformers so bear with me..Thanks.
 Rick.

DrGonz78

The 30 vac refers to the AC voltage but after rectification to DC voltage it will be higher. 30vac * 1.414 = 42.42vdc.
"A person who never made a mistake never tried anything new." -Albert Einstein

mr.death