Peavey KB2 Schematic - Please Repost

[bobvines]

Would someone please repost the schematics for the Peavey KB2 keyboard amp? They appear to have been lost when the other files here were lost earlier -- all I see is the gif of a white dot instead of the previously posted schematics PDFs.

I'm trying to troubleshoot a KB2 for a friend and have contacted Peavey asking for the schematics, but I'm hoping someone here can respond faster than they can since it's a long weekend. The KB2 has begun to "buzz" when low notes are played, but not on the higher notes. I noticed today that the power light seems to flicker in time with the buzz, so I'm thinking this is an electronics problem instead of a bad (coax) speaker. The output also seemed to be cutting out when I first powered up the KB2 -- the power light also flickered when this happened.


Thanks,

Bob

[Jazz P Bass]

Peavey KB2 Schematic

With the problems that you are seeing, I would take a long , hard look at the power supply soldering.
Reflow the board if it looks flaky.

[bobvines]

Thank you for (re)posting the schematics. I'll print them out on a large printer tomorrow. I will definitely look closely at the power supply soldering.

I also found a post here by someone whose KB2 had been dropped, breaking the power transistor connections. I suppose my friend's KB2 could have similar broken solder joints and the low notes that cause the buzzing are actually hitting the natural frequencies of the physical board/components and possibly causing the components to make & break contact -- giving the buzzing.

I'll report back with whatever results I get.


Thanks,

Bob

[bobvines]

Sorry for the *extremely* slow response. Either U2 or U3 (I forget which) had a broken solder joint and was vibrating at, I guess, a harmonic frequency when certain low notes were played. These two voltage regulators stand straight up on the board and their heat sinks are bolted on to them with no support. I assume that the relatively large unsupported mass of regulator & heat sink broke the solder joint. Reflowing all of the solder joints on both regulators fixed that problem.


Bob

[Randall]

I have a KB2 in with the same problem. Shame the PS is not included in the schematics.

[Enzo]

Page 1 of PA schematic shows PS doesn't it? Omits transformer but we know what that does anyway.