LegginsWill
Member
Hello all!
I have started restoration of a Pioneer QX-8000a due to some weird sounds (high pitched oscillating sound) and hissing in the left front and rear channels, but I’ve ran into an issue. I have replaced all the blue Sanyo caps on the head amp, control, logic, and decoder board, as well as replaced the 2sc1344 transistors on the head amp. This was successful in getting rid of the weird sounds I was getting, but I still have the hiss in the left channels, the rear one is also slightly distorted. Right channels are clear as day.
Now, I have cleaned all pots many times before and after recapping the boards to no avail. I have also tried to find the source by eliminating which boards it could be.
Notes I have found trying to find which board it could be:
The hiss is controlled by the volume in both left channels, except it disappears when the volume is a little below halfway, and at full blast.
When the main and pre amps are separated by the switch, the hiss goes away. When separated and connected with RCA interconnects, the hiss returns. This lead me to believe Pre-amp was the issue.
Treble controls make the hiss worse as it increases in the respective front/rear left channels.
I am new to stereo repair and this is my first try at electrical work on a receiver. I’d like to save this receiver if I can as I’d like to get back into quad and I’d like to succeed at my first electrical repair, but I just can’t seem to solve this hiss… if anyone has any suggestions or has ran into this issue in the past, I would greatly appreciate any info on what I can try to do!
Thanks!
I have started restoration of a Pioneer QX-8000a due to some weird sounds (high pitched oscillating sound) and hissing in the left front and rear channels, but I’ve ran into an issue. I have replaced all the blue Sanyo caps on the head amp, control, logic, and decoder board, as well as replaced the 2sc1344 transistors on the head amp. This was successful in getting rid of the weird sounds I was getting, but I still have the hiss in the left channels, the rear one is also slightly distorted. Right channels are clear as day.
Now, I have cleaned all pots many times before and after recapping the boards to no avail. I have also tried to find the source by eliminating which boards it could be.
Notes I have found trying to find which board it could be:
The hiss is controlled by the volume in both left channels, except it disappears when the volume is a little below halfway, and at full blast.
When the main and pre amps are separated by the switch, the hiss goes away. When separated and connected with RCA interconnects, the hiss returns. This lead me to believe Pre-amp was the issue.
Treble controls make the hiss worse as it increases in the respective front/rear left channels.
I am new to stereo repair and this is my first try at electrical work on a receiver. I’d like to save this receiver if I can as I’d like to get back into quad and I’d like to succeed at my first electrical repair, but I just can’t seem to solve this hiss… if anyone has any suggestions or has ran into this issue in the past, I would greatly appreciate any info on what I can try to do!
Thanks!
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