Your opinion would confirm my measurements, because I have not found differences in the resistance measurements between the left and right channel, I suppose that is synonymous with careful construction... by the way, I have discovered the - probable - cause of the failure of the original potentiometer.....
I'm sorry if I'm going too far from the original topic, but since I don't have much to tell, it's not justified to open a new thread just for this.
Regarding the failure of the potentiometer (obvious volume differences between channels and in position 0 it does not completely cut the volume) You can see the remains of carbon from the tracks (the dark color) scattered in various parts of the potentiometer. And it had already been cleaned with cotton swabs and isopropyl alcohol, it was much worse! I conclude that the carbon in the tracks has degraded over time and with use, poor quality contact cleaners have probably helped this process. Be careful with that. Here we only get one brand, which says "does not attack plastics", it is assumed that it would not attack the carbon on the tracks.... 🤔
Regarding the failure of the potentiometer (obvious volume differences between channels and in position 0 it does not completely cut the volume) You can see the remains of carbon from the tracks (the dark color) scattered in various parts of the potentiometer. And it had already been cleaned with cotton swabs and isopropyl alcohol, it was much worse! I conclude that the carbon in the tracks has degraded over time and with use, poor quality contact cleaners have probably helped this process. Be careful with that. Here we only get one brand, which says "does not attack plastics", it is assumed that it would not attack the carbon on the tracks.... 🤔
Attachments
Well, without haste but with enough pauses, the amplifier is working and almost in perfect working order, I will open a new thread (the failures and the consequent repairs of the Sansuí AU 4900 is a widely publicized topic on the networks, and not all opinions agree on the diagnosis) so I think my experience can help someone, I know people who love this small but beautiful vintage amplifier and they haven't been able to repair it, so they keep it just to show off along with the rest of their system.
"Almost perfect" is an issue that I consider easy to solve, but it is always good to know what others think. That will be tomorrow, it's already late here.
"Almost perfect" is an issue that I consider easy to solve, but it is always good to know what others think. That will be tomorrow, it's already late here.
Attachments
