Hi folks. I have a Marantz 2252B here. It now has new caps and transistors on the board attached to the tone controls, all new caps/transistors on the board attached to the source selector, and I have cleaned and lubed the controls. I have also put in a new power switch (old one was going bad) and I have set the power supply, bias, and DC offset voltages, none of which were significantly off.
This still has the problem that it came to me with, which is a hum and crackle on the left channel. When I plug directly into the rear Main Ins, there is no hum/crackle. The hum/crackle vary with volume, and switch sides when I use RCA cables to swap the pre outs/main ins left to right. I tried running RCA cables from the Pre Outs to the Main Ins and the problem is still there.
Now, here's where it gets fun. When I push or pull on the relay in the right way, the hum/crackle vanishes entirely. I tried redoing all the solder joints on the relay and all the ones in the vicinity. No change. I tried replacing the caps and transistors around the relay. No change. I tried removing the relay and polishing the contacts. No change. I poked and prodded and pushed and pulled on the circuit board. No change.
The hum measures around .1 VAC on the left channel. No AC on the right.
At this point should I just put in a new relay, or is it likely to be something else?
This still has the problem that it came to me with, which is a hum and crackle on the left channel. When I plug directly into the rear Main Ins, there is no hum/crackle. The hum/crackle vary with volume, and switch sides when I use RCA cables to swap the pre outs/main ins left to right. I tried running RCA cables from the Pre Outs to the Main Ins and the problem is still there.
Now, here's where it gets fun. When I push or pull on the relay in the right way, the hum/crackle vanishes entirely. I tried redoing all the solder joints on the relay and all the ones in the vicinity. No change. I tried replacing the caps and transistors around the relay. No change. I tried removing the relay and polishing the contacts. No change. I poked and prodded and pushed and pulled on the circuit board. No change.
The hum measures around .1 VAC on the left channel. No AC on the right.
At this point should I just put in a new relay, or is it likely to be something else?
