Aragon r4004 mkii right channel no sound

[pjstone]

I have a 4004 mkii that the right channel produces no sound. This is what I have observed. The relay looks terrible through the plastic. I havent tried to take it out or open it.

I have biased and set dc offset which is pretty much spot on at +-2mv dc offset and bias at 9.9. I see no burned parts fuses are good rails are 70v.

I have measured a high esr on the right channel driver board of 5 or 6 ohms on one of the orange 1000uf 16v caps. Not sure if that would cause the issue.

I have not tried to bypass the relay on the right channel to see if i get sound. I have noticed that if i tap the case sometimes the left channel will go out and a tap will make it come back.

I have ordered a new relay from mouser or digikey cant remember which right now. What do you think? Am i on the right road?

Thank you so much

Phil

 

[Buck Rogers]

Usually you just smack the relay a couple of times and if it's the contacts you will get intermittent sound.

High failure part.

 

[pjstone]

i can tap it and get the left channel to drop in and out but not the right. hmmmm....

 

[chazix]

fuses are good

FWIW, I recently had a 2004 mk2 with a channel out, and the rail fuses for that channel looked good, but measurements on the "downstream" fuse clips showed that the fuses were open.

(And the amp worked normally after just replacing the fuses, which was a bit of a surprise. Made me wonder what could have been the fault condition that would make both + and - rail fuses blow, but apparently with no harm elsewhere in the amp. I guess shorted speaker wiring could act like that.)