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Thread: Peavey Delta Blues Hum - Recap and Cleanup

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    Peavey Delta Blues Hum - Recap and Cleanup

    MEF members:

    A friend asked me to look at his Peavey Delta Blues. The amp has a loud hum - the power supply type. We plan on replacing the caps in the Power Supply. Before doing anything else, I was doing a visual inspection and found something around CR11 to CR14. These are the diodes for the low supply. Am I looking at old adhesive that is discolored or do you think something else could be going on there?

    Thanks,

    Tom
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    Woah, man! That's a weird one. What does that substance feel like, when you probe it? Hard, soft, flakey, sticky?

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    Lifetime Member Enzo's Avatar
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    That is hot melt glue, it is from gluing the nearby filter cap to the board. The two resistors on the right - on the next board - run warm, and the heat has discolored the glue puddle near the leads.

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    Education is what you're left with after you have forgotten what you have learned.

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    xtian and Enzo....

    Yes, after a closer examination, it is hardened glue. Thank goodness cause I didn't want to send it to the lab for a biopsy.

    For those visiting this thread, there are some videos on YouTube related to "Peavey Classic 30 Hum Recap" etc. The Classic 30 and Delta Blues are identical so you'll see the process for doing this. In addition to the Power Supply Caps, there is one more you might check and consider changing. It is C65, 1000uf, 35v IC brand capacitor. The IC brand have been known for, well let's just say, a lack of quality? On the schematic, you will find this cap close to V7, look down then left.

    Since I do not "stock" boxes of caps, we decided to buy a Capacitor Kit from a dealer on eBay. He sells F&T. I just happen to have a 1000uf cap for C65.

    I'll report back next week on the Hum after replacing the Power Supply caps.

    Go Niners !!!!

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    Lifetime Member Enzo's Avatar
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    Niners-schminers... I'm rooting for "the kid".

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    I'm all about the Puppy Bowl!

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    All I can see in that photo are those darned connecting wires between boards. They give me chills.

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    It's weird, because it WAS working fine.....

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    When you get the boards out look closely at all jumper wire connections between boards, the solder often cracks there. Also re-solder all the tube sockets. I've also had trouble with filament connections for the power tubes. The four are connected in series so a bad solder connection on any jumper carrying heater current will cause all power tubes to die.

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    Supporting Member TomCarlos's Avatar
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    I am working on the recap. Oh my lord, glue glue everywhere!! I think someone on the Peavey assembly line went glue happy and they let this one through! I have been very careful to extract the caps. As you can see from this photo and the one above, it is a mess. You can see a resistor totally encapsulated in glue.

    Randall, yup, the connecting wires are a concern. And as I look at the touching points of the pc boards, there is little room between solder points and traces from one board to the next.

    Back to work...
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    Oh... one more thing I found ... next to the diodes that were swimming in goop... I thought it would be a good idea to check the fuse holders to make sure they were clean. As you can see from this pic, the 10 amp fuse socket had melted glue and the fuse itself. So I cleaned that up too!!
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  11. #11
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    Epilog...

    Amp is working. C42, a 22uf, 450v cap was open. As noted above, I replaced all caps in the Power Supply with F&Ts and C65. All is good.

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