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Turn on Thump and turn of "pop" K100C-8 [message #25965]

Sun, 26 February 2017 16:27

Saransk
Messages: 20
Registered: February 2017
Location: Northern Virginia

Junior Member

Picked up a "working" K100C-8 for basically shipping - and got a nice deal.
I've worked on amps for almost 40 years - first Kustom Tuck-N-Roll
Needs all 4 speakers and some cabinet work
Electronics seem to be in good shape - but show the usual aging. (New jacks for sure)
The usual grime and such, but no evidence of any "hacked" repair work.
After some capacitor replacing, and changing the AC cord and switch out for a 3-prong I fired it up

There is a loud "thump" when it turns on - not sure if that is normal, I know it can be typical for direct coupled amps.
And sort of of "pop" when I turned it off.
Voltages seem in good shape
Normal side works fine, Effect side - not so fine. (volume goes up then down - have to look at the feedback loop - issues with the tone stack)
The usual noise and such

Right now I'd like to find out if a turn-on "thump" is common, if not, any suggestions.
There is about 21mV dc on the output and it does swing back and forth when I shut down.
Is the thump just part of the "charm" (I once used a Fender FM100 that thumped enough to scare you) - or can it be lessened

Thanks

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