Hello fellow forum members,
I've purchased this amplifier in used condition for mid-bass duty in a bi-amp setup. The problem is when idling it gets too hot. Can you help me set the correct bias voltage? I see two test points on the main board TP1 and TP2. Below I attach a photo of the amp. You can see the heat damage on the pcbs. Any help greatly appreciated.
I've purchased this amplifier in used condition for mid-bass duty in a bi-amp setup. The problem is when idling it gets too hot. Can you help me set the correct bias voltage? I see two test points on the main board TP1 and TP2. Below I attach a photo of the amp. You can see the heat damage on the pcbs. Any help greatly appreciated.
Attachments
Also on the silk-screening is "IDLE", presumably on the other side is the bias trimmer.
Found the schematics/service manual:
Inter m r150 r300 r500 Power Amplifier Service Manual
TP1 and 2 are either end of two 0.47R emitter resistors.
As its an emitter-follower output stage try in the first instance for 50mV between testpoints TP1 and TP2, ie about 50mA per output pair.
Found the schematics/service manual:
Inter m r150 r300 r500 Power Amplifier Service Manual
TP1 and 2 are either end of two 0.47R emitter resistors.
As its an emitter-follower output stage try in the first instance for 50mV between testpoints TP1 and TP2, ie about 50mA per output pair.
Well that's not unreasonable, it ought to be running cool. Can you measure the actual current consumption from the DC supplies?
Or the actual values of the emitter resistors - if they've changed in value that could be a reason. Also oscillation (ultrasonic or RF) might be another possible cause.
Thanks for the schematic but this is from the older model I have the plus model and I already have the service manual for that model. As for the bias I've set both channels at 30 mV. Now it runs a little colder on idle. If anyone knows the exact voltage it will be great.