1992
NAD 906 6-channel power amplifier
10 min 1: 27,4 2: 31,8 3: 37,4 4: 34,9 5: 36,2 6: 33,1 mV
20 min 1: 26,1 2: 30,4 3: 35,8 4: 33,5 5: 34,8 6: 31,8 mV
40 min 1: 25,8 2: 29,9 3: 35,4 4: 33,2 5: 34,4 6: 31,5 mV
80 min 1: 25,4 2: 29,8 3: 34,6 4: 32,7 5: 33,5 6: 31,0 mV
160 min 1: 25,2 2: 29,5 3: 34,2 4: 32,5 5: 33,0 6: 30,8 mV
I will clean the internals and try to adjust offset a little better, probably not opened since -92.
EDIT:
After cleaning I adjusted the idle current to 5 mV according to the manual, however there seems to be no adjustments for offset, so the DC voltage at the outputs remains the same as before.
Another thing I noticed:
When bridging channel 1+2, 2+3 and 5+6 I got much lower readings of DC
1+2: 2,7mV
3+4:1,7 mV
5+6: 4,7 mV
I dont know why, maybe sombody can explain this
"Before" pic
After cleaning