Hi guys, need some help. Just got a working A&R SA200 power amp.
I noticed that a previous owner had probably exchanged the +ve and -ve fuses with M4 screws (as you would..) and burnt the rail resistors and the pcb itself. Someone repaired it.
It is working on that channel but I found that RV3 for the clip indicator is totally differently set in each of the identical channels. Whilst the one in the unrepaired channel is fully open (0.8ohm) the one in the repaired channel is set to 75k.
I am going to recap the amp and want to adjust but could do with some gudiance how this clip indicator circuit works and wha to set things to. Arcam are always good and helpful with schematics and I can find my way around their drawings but just lack the essential knowledge to work things out sometines.
The IC is an RCA 1458, the amp is from 1981 or thereabouts, it is a nice dual mono layout with proper discrete components in it.
I attach the schematic here, it's also available from HiFi Engine.
Any help, especially explaining how this part of the circuit works would be very welcome.
Many Thanks
I noticed that a previous owner had probably exchanged the +ve and -ve fuses with M4 screws (as you would..) and burnt the rail resistors and the pcb itself. Someone repaired it.
It is working on that channel but I found that RV3 for the clip indicator is totally differently set in each of the identical channels. Whilst the one in the unrepaired channel is fully open (0.8ohm) the one in the repaired channel is set to 75k.
I am going to recap the amp and want to adjust but could do with some gudiance how this clip indicator circuit works and wha to set things to. Arcam are always good and helpful with schematics and I can find my way around their drawings but just lack the essential knowledge to work things out sometines.
The IC is an RCA 1458, the amp is from 1981 or thereabouts, it is a nice dual mono layout with proper discrete components in it.
I attach the schematic here, it's also available from HiFi Engine.
Any help, especially explaining how this part of the circuit works would be very welcome.
Many Thanks