Trying to figure this one out, when my protection relay closes, especially if the unit was turned off, left for a minute or so, and then turned on I get a pop of DC out of both my left and right speakers. Measuring the DC shows roughly 100-200mv when the relay closes, quickly dropping to 0. If I cycle the power the relay will close with around 500mv (probably because the relay delay cap hasn't fully discharged and thus a shorter close time).
What I can tell is that the DC is coming from the preamplifier and not the main amplifier, as with the jumper switch in separated (DC) mode there is no pop and the DC offset is low when the relay closes. The only thing I can think of is if the protection relay is closing too soon (from what I can tell when the protect relay closes it also closes the reed relay in the preamp). Being that it is in both channels I would suspect the power supply, however, my +-33v rails are spot on. Is there anything that would cause the preamp to have not settled by the time the relay closes (or is the relay circuit closing too soon/not detecting DC how it should)?
I have been restoring it similarly to this thread (the only real change was UF series diodes instead of the diodes used here for the rectifiers, and replacing the two 2sc1636 in the protect circuit with KSC1845), so far only the power supply/protection and the amp cards have been done :
https://audiokarma.org/forums/index.php?threads/project-sansui-g9000.952191/
What I can tell is that the DC is coming from the preamplifier and not the main amplifier, as with the jumper switch in separated (DC) mode there is no pop and the DC offset is low when the relay closes. The only thing I can think of is if the protection relay is closing too soon (from what I can tell when the protect relay closes it also closes the reed relay in the preamp). Being that it is in both channels I would suspect the power supply, however, my +-33v rails are spot on. Is there anything that would cause the preamp to have not settled by the time the relay closes (or is the relay circuit closing too soon/not detecting DC how it should)?
I have been restoring it similarly to this thread (the only real change was UF series diodes instead of the diodes used here for the rectifiers, and replacing the two 2sc1636 in the protect circuit with KSC1845), so far only the power supply/protection and the amp cards have been done :
https://audiokarma.org/forums/index.php?threads/project-sansui-g9000.952191/