Home » VintageKustom.com » Repairing Kustom Amps » Kustom Bass III Channel 1 Hiss (extreme amount of hiss on channel 1 board (PC5127))
Re: Kustom Bass III Channel 1 Hiss [message #28745 is a reply to message #28739] Sun, 21 August 2022 09:11 Go to previous message
thespeakerport is currently offline  thespeakerport
Messages: 11
Registered: July 2022
Junior Member
Again, sorry for the delay in responding. Been a crazy past month with workload. The customer decided to take back the unit and just disconnect this channel and use the other for the time being. He needed it back and could not wait any longer. But to answer as many questions as i can, see below:


This brings up another question, your brite switch shorted and on all the, because that adds a lot more hiss? <-The bright switch did not really make any different in the hiss...but it is effective to the sound.

On boards 5066 boards made after 11 of 1971, R29 was changed from 8200 to 4700 to add more gain to the 5067 board, so maybe try going back to 8200. <-Did not know this, if the customer brings it back in....i can give this a try.

Just to confirm and go back to square one here, when you turn down the volume pot on that 5067 board all the added hiss goes away, right? <- that is correct. No hiss at all if the volume is all the way down.

On the 5966 board do R6 and R16 both test within 10%? <-Initially all resistors tested within spec with the exception of about 3 or 4 carbons. The entire board had all the resistors replaced. The low tolerance resistors i used metal film versions. I did not have 1% grade versions, but i went through what i had and tested each until i found ones that were as close to target value as possible. None of this work made any difference at all.

And does R5 test within 1% ?

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