Pomegranate
Active Member
Hi everyone!
I recently bought an Onkyo Integra amplifier that I've been on the lookout for for a long time. Onkyo Integra A-R700, identical to the A-8780 model. It's in really good condition on the outside, but it had two issues when I turned it on.
First, when the volume knob was turned all the way down, from the left speaker came music at a normal volume. And secondly, the left channel was a little quieter than the right one.
For the first problem, I read a post by someone else that the rotary potentiometer had two plastic discs inside and one of them was cracked. This line of amplifiers use a motorized, two-way rotary potentiometer made by Alps (I believe also called Blue Velvet?). Replacements are very expensive and most likely fake, so I decided to open up the potentiometer and glue that disc back together.
It's quite difficult to access the assembly, I had to take the entire front plate off. But I got to it in the end, took it apart and glued the disc with some super glue. I put everything back and now the issue with the left speaker is resolved. I guess it made sense why the left channel had the problem, as it is the disc closest to the end of the shaft and gets more tension when turned. Probably the previous owner turned it with too much force.
But the problem with the slight imbalance on the channels is still there. Do you think the potentiometer is still to blame for this? I sprayed contact cleaner on the other potentiometers, on the fuses and on the main relay. I couldn't open the speaker relays also, but this problem appears on both channels, so I don't think they are the problem.
One thing I also suspect is the knob for switching between Tone and Source Direct. It has a linear switch inside that I also sprayed, but sometimes when I switch it on Source Direct, the right speaker gets much louder than on Tone. Or maybe the main capacitors? They look like they have started to bulge, but I'm not sure. And the other capacitors in the circuit seem to be fine.
I'm also planning to look for a spare potentiometer, just in case my repair won't last long. But the ones I see for sale have only three prongs for each channel, whereas mine has four. Would the ones with only three work?
I recently bought an Onkyo Integra amplifier that I've been on the lookout for for a long time. Onkyo Integra A-R700, identical to the A-8780 model. It's in really good condition on the outside, but it had two issues when I turned it on.
First, when the volume knob was turned all the way down, from the left speaker came music at a normal volume. And secondly, the left channel was a little quieter than the right one.
For the first problem, I read a post by someone else that the rotary potentiometer had two plastic discs inside and one of them was cracked. This line of amplifiers use a motorized, two-way rotary potentiometer made by Alps (I believe also called Blue Velvet?). Replacements are very expensive and most likely fake, so I decided to open up the potentiometer and glue that disc back together.
It's quite difficult to access the assembly, I had to take the entire front plate off. But I got to it in the end, took it apart and glued the disc with some super glue. I put everything back and now the issue with the left speaker is resolved. I guess it made sense why the left channel had the problem, as it is the disc closest to the end of the shaft and gets more tension when turned. Probably the previous owner turned it with too much force.
But the problem with the slight imbalance on the channels is still there. Do you think the potentiometer is still to blame for this? I sprayed contact cleaner on the other potentiometers, on the fuses and on the main relay. I couldn't open the speaker relays also, but this problem appears on both channels, so I don't think they are the problem.
One thing I also suspect is the knob for switching between Tone and Source Direct. It has a linear switch inside that I also sprayed, but sometimes when I switch it on Source Direct, the right speaker gets much louder than on Tone. Or maybe the main capacitors? They look like they have started to bulge, but I'm not sure. And the other capacitors in the circuit seem to be fine.
I'm also planning to look for a spare potentiometer, just in case my repair won't last long. But the ones I see for sale have only three prongs for each channel, whereas mine has four. Would the ones with only three work?
