Blues Jr. Mod Problem

[jguay]

Hi All. I just installed a few of the BillM mods in my BJ and ran into a possible problem. Just curious if anyone here could give me any insight at all into what may be going on with my Blues Junior.

1) Installed tone stack mod - no problems.
2) Installed audio-taper master volume pot - no problems.
3) Installed twinstack mod - no problems.
4) Installed power supply stiffening mod - no problems.
5) Installed simple adjustable bias kit - POSSIBLE PROBLEMS.

After removing R51 & R52, I then carefully drilled the 2 holes and installed/soldered the trimpot along with the wire connecting the middle lead to an open hole for R51. Removed EL84's, powered up & measured/set voltage at C- (top of R31 or R32) to -13V. OK so far. Reinstalled & secured board, put EL84's back in, powered up, then measured the voltage between the OT RED & BROWN and adjusted to 2.56V (based on RED/BROWN resistance of 102.5 ohms). The problem is my meter goes wild when I try to measure between RED & BLUE. Measuring just RED to ground is 328V, BROWN to ground is 326V, and my meter goes wild again when I try to measure from BLUE to ground.

Then amp sounds and plays fine (the improvements are evident), but I'm very nervous about the problems I described above. I would GREATLY appreciate ANY help or insight into what is happening with my amp. Thanks, in advance

jguay

[jguay]

I emailed BillM last night and got an answer to my questions - sounds like the Phase Inverter was oscillating while I was taking readings. Bill reassured me that all should be fine. Thanks anyways (and a BIG THANK YOU to BillM).

[danii]

Say, did you order your parts for the mod off of BillM or through somewhere else? I've been wanting to mod my BJr for a while.