Roland JC120 no chorus

[pontiacpete]

Vibrato works and the switch tests good. So I narrowed it down to the mn3007 chip. Replaced it and now the chorus works and the vibrato but the normal, no effect, sound is very low and weak and distorted.
Does this mean I need to change out the 3101 IC, also?

thanks for any help.
pete

[pontiacpete]

changing the 3101 didn't do a thing.
But, and I probably should have tried this first, when inserting a short 1/4" plug into the 'main in' the clean channel volume comes back.
Not sure what this means, though

MN3007 has 14v on pin1 and 6.6v on 7and 8

[pontiacpete]

This is getting strange now. The sound is now back to being equal with/without effect, but the chorus is weak.
The depth and the speed seem not make much of a difference or if any difference at all. The vibrato does work and speed and depth are very apparent.
Any ideas?

[52 Bill]

A couple of things here. First the MN3101 is a controller for the MN3007. If the chorus and vibrato works, then both chips are usually okay.

The speed and depth controls only work on the vibrato effect. The chorus is preset to one setting.

Have you cleaned both of the main in jacks? Give all of the jacks a good cleaning for that matter.

Watch the speaker wiring, as phase is very important for the amp to sound right.

[pontiacpete]

Cleaned all the jacks again. Checked for the proper phase of the speakers..
Thanks for clearing that up for me. I guess I have noticed that about depth and speed controls only being for the vibrato.
Geez can't believe I didn't remember that..I've used these in past many times in studios. Now I'm starting to doubt that the chorus was ever broken in the first place. Guess the owner will know .
Thank you very much for the help!!
pete