afroaudio
Active Member
Hi gang,
I am in the process of restoring my AU717. I have so far completed the main amp boards (amp tested good after these were completed)
This week I managed to get my 2663 power supply board out and recapped. I also decided to replace all diodes with UF4004/1N4148 where appropriate as well as the Zeners (paid attention to 5.6, 6.2 and 13V versions) and the VD1212. Also replaced TR603 and the relay with an Omron MY02. Main filter caps also replaced with 15000/63 Nichicons.
I managed to get the PSU board and main caps back into the chassis and wired up today.. took me the entire morning! Powered up on a dim bulb which looked good but now measuring voltages at the top of the F-2663 board I am getting the following:
Between point 21 (gnd) and 23: - 34.8V
Between point 21 (gnd) and 19: +35.8V
Between point 22 (gnd) and 24: -15V varying to - 18V approx
Between point 22 (gnd) and 20: +15V varying to +18V approx
I checked the DC at the speaker terminals and set to near zero mV.. all good
Bias adjusts fine and is set at 20mV as per service manual.
Both channels of the amp play fine but the volume on Left channel is much lower than Right. I have a horrible feeling I will be needing to undo all my work today and take the 2663 board out again and figure out what went wrong there. Any pointers at trouble shooting would be great!
I am in the process of restoring my AU717. I have so far completed the main amp boards (amp tested good after these were completed)
This week I managed to get my 2663 power supply board out and recapped. I also decided to replace all diodes with UF4004/1N4148 where appropriate as well as the Zeners (paid attention to 5.6, 6.2 and 13V versions) and the VD1212. Also replaced TR603 and the relay with an Omron MY02. Main filter caps also replaced with 15000/63 Nichicons.
I managed to get the PSU board and main caps back into the chassis and wired up today.. took me the entire morning! Powered up on a dim bulb which looked good but now measuring voltages at the top of the F-2663 board I am getting the following:
Between point 21 (gnd) and 23: - 34.8V
Between point 21 (gnd) and 19: +35.8V
Between point 22 (gnd) and 24: -15V varying to - 18V approx
Between point 22 (gnd) and 20: +15V varying to +18V approx
I checked the DC at the speaker terminals and set to near zero mV.. all good
Bias adjusts fine and is set at 20mV as per service manual.
Both channels of the amp play fine but the volume on Left channel is much lower than Right. I have a horrible feeling I will be needing to undo all my work today and take the 2663 board out again and figure out what went wrong there. Any pointers at trouble shooting would be great!