Roland Jazz Chorus 120 "Schematics needed asap"

[studiologos]

Hi eveyone, I need help. I have a old first series (1975-1978) Roland JC120 amp, it works and plays, but has a horrible buzz, my buddy the amp tech needs the schematics to fix it properly, but we havnt found the schematics that we need, can someone point out where i can find one or buy one?

PS: I have the 1979, 1984 schematics and they are not the ones, we need the ones 1978 or before................. Thanks

[Enzo]

Hi, welcome.

Have you done a search on this forum? We have a number of JC120 threads, with various links and postings included.

[chipprogr]

Has he checked the main power supply caps for AC ripple? You should be able to do that without schematics.

[Enzo]

And should be able to isolate the problem to power amp or preamp.

[barryachi]

I have a roland jc 120 serial #272826. I've fixed the amp head part of the amp. It has been so long that I am not sure where the speaker wires go to the posts on the speakers. It must be one of the first ones and I can't find a schemitic for this amp. The wires coming from the head to the speakers are brown, red, black, and orange. I don't want to make a mistake at this point. Or do I just put them on and switch them around. Thanks barryachi

[vintagekiki]

... It has been so long that I am not sure where the speaker wires go to the posts on the speakers ...

may be helpful
http://music-electronics-forum.com/t7116/