Oddball Roland JC-120 Jazz Chorus schematic needed

[audiopete]

I need a schematic for a 81-82 Roland JC-120 with brite switch and toggle switch chorus/vibrato. I've checked 3 different available schems and they don't match. This amp has an MN3004 BBD chip and MN4013B CMOS clock. I see a trimpot but not sure if it is BBD bias or not. I want to see if I can calibrate the chorus/vibrato better.

Thank you very much.

[g1]

Try the 11016 version in here:
http://www.schematicsforfree.com/arc...d%20JC-120.zip

[audiopete]

Thanks but the zip file is empty (0kB) I went to the site but apparently my download limit is exceeded by downloading an empty zip file twice.

[audiopete]

I found the correct circuit in the JC-60 schematic, so don't worry about it, but thank you g-one. The trimpot is a balance pot for the bbd outputs. Bias is resistor set. I'm going to look at it on the scope and see if it is set for optimum balance and bias.

[g1]

Sorry about that, here they are, a few at a time as some are large:

[audiopete]

Sorry about that, here they are, a few at a time as some are large:

Bingo! Thanks again! The 11016 was the one. Same chorus circuit as the JC-60 I found.

I checked the chorus circuit and it was pretty much still calibrated to optimum and sounds great.

The client also had an issue with the imbalance in hiss between the two power amps. He noticed it when the amp first fires up and the chorus side power amp comes up. It is hissier than the clean amp. I told him that was normal. I also told him all these amps are hissy - a common complaint of these over the years.

I scoped the two power amps before and there was maybe a 2dB difference in output - not really detectable by ear. Both sides are even by ear without any effects but I think the clean speaker/effected speaker was throwing him, not realizing the architecture of the amp.