Those Voltages are correct, you just measured them in the wrong place.
68.2 divided by 2 = 34.1 which is close enough to spec.
You just measured across both + and - Voltage rails, forgot the common center tap.
Same with low supply, 29.4 is the potential across + and- rails.
Both Preamp and poweramp supplies use a split supply where you have 3 wires from transformer the center tap is the common or Zero point.
Sadly none of this helps much as the amp is faulty.
There looks to be a mute circuit hung off pin 6 of U1b consisting of Q1 & Q2 which may have failed causing very low output.
Other here will know more.
Phil.
68.2 divided by 2 = 34.1 which is close enough to spec.
You just measured across both + and - Voltage rails, forgot the common center tap.
Same with low supply, 29.4 is the potential across + and- rails.
Both Preamp and poweramp supplies use a split supply where you have 3 wires from transformer the center tap is the common or Zero point.
Sadly none of this helps much as the amp is faulty.
There looks to be a mute circuit hung off pin 6 of U1b consisting of Q1 & Q2 which may have failed causing very low output.
Other here will know more.
Phil.