"At idle, with no input, the front (short) tube should have the following DC voltages on its pins:
1/6: 150 to 200 or so
2/7: 0
3/8: 2.6 (but 3.6 might be ok)
The two tall tubes should have the following DC voltages (both tubes should have the same DC voltage on same pins)
2: 0
3: 10
6: not sure - floating for DC, so DC measurement doesn't mean much
7: 350 - 400
8: 350 - 400
If pin 3 is 3.6v that's too low, something is wrong
TPA at 404 and TPB at 354 is probably ok, it just means your power transformer is a little hotter than the original."
-----------------------------------
DanK, thanks for the reply. I've just returned from vacation, re-read your post, and made new measurements.
At idle, with no input, the front, short tube measures:
1/6: L 199, R 203
2/7: L 0, R 0
3/8: L 3.76, R 3.78
Two, tall tubes:
2: L 0, R 0
3: L .48, R .48 (multimeter set to 60 vdc knob where steps are 600m, 6, 60, 600, 1000)
7: L 435.8, R 436 (both of these have small flick/spark when measured)
8: L 0, R 0
It is entirely possible--and I wouldn't be surprised or offended--that I'm measuring wrong. I watched some YouTube videos on "how to measure DC." I turned the chassis upside down so that it rests on the power transformer and a cut 2x4. The bottom of the chassis is, right now, exposed so that I can access the board. I put the black lead on the chassis ground and the red lead to the points indicated. These measurements were at volume 0. The amp hums very very quietly, but at volume 0-6'ish, it squeals/whirls very high pitched. At more than 6 volume, it disappears and the amp is very quiet--just the slight, barely audible hum.
Here are two more photos:
image2-1 by
Jason, on Flickr
image1-1 by
Jason, on Flickr