special_20
Active Member
I picked up a cosmetically minty looking Marantz 2015 this morning. Unit was advertised as having some issues: missing right channel and lights out. Bought it hoping it was dirty pots or maybe a bad capacitor. This one however has me a bit stumped. Unit is clean inside and out. No obvious part faults internally. I deoxited the controls and pots and switches work with no static or crackle in the working left channel. The balance switch does seem to not go all the way to right.
Hifiengine has a manual however, it's pretty sparse on details though. Based on schematic and info gleaned from threads here at audiokarma, the amp section appears to be working. I am getting the voltages listed in the service manual off the 4 output transistors (~23v for each) and I was able to adjust bias (7.5mv) and DC offset (~0.1mv) for both the left and right channel. So I've got juice, which means I'm not getting signal.
Seems like my problem exists somewhere between input and the amp. Tone controls seem to work fine; likewise switches seem to be fine - no pops or static in good channel when playing with the knobs and switches. As mentioned above, fader doesn't move all the way through it's mechanical range.
I'm hoping someone has some tips on how to trouble shoot this. Am I right to suspect the fader? Is there a way to test it by measuring resistance through the range? Is it worth taking apart and inspecting? Tips and suggestions appreciated. Hope to get this girl singing again!
Thanks in advance!
Hifiengine has a manual however, it's pretty sparse on details though. Based on schematic and info gleaned from threads here at audiokarma, the amp section appears to be working. I am getting the voltages listed in the service manual off the 4 output transistors (~23v for each) and I was able to adjust bias (7.5mv) and DC offset (~0.1mv) for both the left and right channel. So I've got juice, which means I'm not getting signal.
Seems like my problem exists somewhere between input and the amp. Tone controls seem to work fine; likewise switches seem to be fine - no pops or static in good channel when playing with the knobs and switches. As mentioned above, fader doesn't move all the way through it's mechanical range.
I'm hoping someone has some tips on how to trouble shoot this. Am I right to suspect the fader? Is there a way to test it by measuring resistance through the range? Is it worth taking apart and inspecting? Tips and suggestions appreciated. Hope to get this girl singing again!
Thanks in advance!
