david winter
Classical music lover.
Hi,
I'm trying to fix this preamp which appears to be an early version.
So far I had one defect 4013 chip and several relays with open coil (I replaced all of them with yellow HB2E-DC24V).
After powering it up, I found that the LEDs of 2>1 Tape Copy and Low Filter always dimmed (or turned on after pressing the corresponding button).
I checked the schematic and found that my pcb was an early version without 3 1N4148 diodes. The dim effect disappeared after adding the two diodes, each between the anode of the relay diode and the LED circuit. One of these two is D41, the other is connected to the anode of D12, but can't reat its reference on the schematic.
Moreover, there's another diode to add, but here again the reference is too blur: it's either the diode under D41 or the other in the empty space on the middle of the pcb (right to the 76800 reference in the SM).
Is there a clearer version of this SM to see where the third diode goes ? Can someone picture those diodes to get their references ?
Thanks.
I'm trying to fix this preamp which appears to be an early version.
So far I had one defect 4013 chip and several relays with open coil (I replaced all of them with yellow HB2E-DC24V).
After powering it up, I found that the LEDs of 2>1 Tape Copy and Low Filter always dimmed (or turned on after pressing the corresponding button).
I checked the schematic and found that my pcb was an early version without 3 1N4148 diodes. The dim effect disappeared after adding the two diodes, each between the anode of the relay diode and the LED circuit. One of these two is D41, the other is connected to the anode of D12, but can't reat its reference on the schematic.
Moreover, there's another diode to add, but here again the reference is too blur: it's either the diode under D41 or the other in the empty space on the middle of the pcb (right to the 76800 reference in the SM).
Is there a clearer version of this SM to see where the third diode goes ? Can someone picture those diodes to get their references ?
Thanks.