Originally Posted by jdelange
C103: I think it was deliberate and not an error. The values are also shown on the PCB layouts. I do use the (V-fet powered) phono quite a lot actually. Speed could be a reason.
C305, assuming this was deliberate too, what would Sony want to achieve?
My electronics knowledge is limited, but I think this works as a low pass filter? So a reduction in capacity increases the frequency range at the low end to pass through to the amp?
Could it be that they did get fried on the earlier amps? I do agree that the voltages shown do not make it logical at first sight. Further down C101 there is 97V on the power supply, but that doesn't get to the caps.
The increase to 100V is probably simply that they had suitable 100V capacitors on the production line already, so they decided to use them. I really wouldn't worry about it.
You are right about C305, it is a filter so that the amplifier does not amplify any DC offset. It is common in a lot of power amp designs. It should be large enough that the low end frequency response is not excessively limited, but small enough that the turn-on thump is not excessive. The thump is mitigated by the output relay however.