"N_Cook" wrote in message
...
Anyone happen to know of a designed-in function that would switch out 1
amplifier of the 2?
Analogue signal of right levels is getting to the inputs of both amps,
which
both agree quiescent DC fashion but some control line is erroneous, I'm
assuming.
Anyone happen to know what switches the A/AB class function , via the 2x
DG211 analogue switches , I assume the user select, amp type, 16 way
encoder
switch, but which for A and which for AB ? but either way seems to control
both amps simultaneously, not isolating one amp.
I thought it would be the 4 way power switch on the rear but that is
switched attenuators only to both amps, no control function. The phones
change over function via the MAX333 an. sw. should divert both amps by the
single ground switch in the phones socket .




Looking at my database, one of these had a mainboard failure (i.e. digital
stuff), uneconomic to repair, One I changed the MAX333, a zener and standard
diode, another was dirty switching contacts (power selector, headphones,
speaker sockets).

I would change the MAX if only to eliminate it. Could be an achilles heel.
I remember years ago I usd to regularly find blown analogue switches - a bit
like the old RAM chips in that they were obviously more prone to failure
than most other chips for some reason.




Gareth.