Audio aero capitole mk2 need help repairing

Yes.

Sorry for the typo, 18.5 volt should be 38.5 volt.

I own my Audio Aero Capitol since new (2004? can't remember exactly). It is a silver unit, there is no mkii marking but it does have the built-in pre-amp. Till this day I am always amazed by its natural and relaxed sound and see no real reason to change.

Which brings me to the question how to keep the unit operational for another decade? I have bought some JAN 6021W tubes and contemplate ordering a CD Pro 2 drive from Enco.

However, it has now developed a problem which has recently gotten worse. It does not unmute when turning on. Usually it can be overcome by toggling power or switching inputs.

I have opened the unit and discovered that the power supply appears weak? The tube supply which is 40 volt at turn on, drops to 18.5 volt when the transport spins up. Also, I find it strange that the balanced line drivers in the output section operate on 13.6 volt as I would have expected the more common 15 volt for such circuits.

I read on this forum that the unit is sensitive to AC power quality and since I am using a balanced power source (Equi-Tech), I have inserted a 1:1 isolation transformer thinking that it may like an unbalanced power source better. This also raises the AC voltage a bit to 130 volt and it did do better for a while but slowly its getting harder again to turn the unit on (unmuted).

Does anyone have some additional thoughts as to what I may try to remedy this muting issue?

Thanks,
Simon

Did some more measurements and it doesn't look too good. The mute control signals are ok but the DAC (AD1853) doesn't get data. The word clock (192K) and bit clock (12.289M) are present but the SDATA line is low. The next part upstream appears to be the Anagram upsampling module but since it is partially covered under the analog input board it is not easily accessible. If the fault happens to be in the Anagram module, repair may get difficult as this company is out of business too? Anyway, I'll think about it for a while before making my next step. In the meantime, I am using the digital output to drive an external DAC.