Hello all,
fortunately, I managed to repair MM section. There were some faulty transistors at right channel but the most important was a missing line at PCB board. In my preamp, base of Q107 was not connected to R113 as indicated at schematics! I do believe that board was modified with an extra jumper when came out from factory, but maybe previous repairman removed this, didn't know that was mandatory for Phono right channel operation.
Next target: MC step-up board.
Meanwhile, I will be more than appreciated if someone send me the rest of schematics. Terje Sandstrom, Electrocompaniet designer, didn't reply to my messages at Facebook...
Stay tuned.
John P.
fortunately, I managed to repair MM section. There were some faulty transistors at right channel but the most important was a missing line at PCB board. In my preamp, base of Q107 was not connected to R113 as indicated at schematics! I do believe that board was modified with an extra jumper when came out from factory, but maybe previous repairman removed this, didn't know that was mandatory for Phono right channel operation.
Next target: MC step-up board.
Meanwhile, I will be more than appreciated if someone send me the rest of schematics. Terje Sandstrom, Electrocompaniet designer, didn't reply to my messages at Facebook...
Stay tuned.
John P.
Update: MC board seems to have signal amplification only at R(-) and L(-) inputs. MC phono has balanced topology with 4 RCAs. R(+) and L(+) do nothing... I am still searching for ECMC-1 board schematics to understand how this topology is implemented. I would highly appreciate if someone send me these.
John P.
John P.
Hi John.
In my case a simple cleaning of the pcb has triggered a problem:
a high frequency oscillation apparently on the right channel.
The input and output buffers are the first ones I checked.
Next I will focus on the line stage which appears to be the
source of the oscillation, if I have some free time I will
draw the related scheme.
-rb
In my case a simple cleaning of the pcb has triggered a problem:
a high frequency oscillation apparently on the right channel.
The input and output buffers are the first ones I checked.
Next I will focus on the line stage which appears to be the
source of the oscillation, if I have some free time I will
draw the related scheme.
-rb