Hi, I have a Roland JC120 and the chorus doesnt work, some recommendation to fix it?
could I turn on to check it without speakers? (I mean is a transistor amp)
Thanks everyone
Roland JC120 (CH doesn´t work)
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Stevem
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Re: Roland JC120 (CH doesn´t work)
Yes, I have worked on many of them and you can power them up with no speakers hooked up, just tape off the ends so they can't short to each other or the chassis.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Roland JC120 (CH doesn´t work)
First off there are many circuit veriations of this amp over the years so I would contact Roland cus service to see how they can help you determine what you have.
I have a schematic at home that I will look at later to see if I can give you any pointers.
I have a schematic at home that I will look at later to see if I can give you any pointers.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
-
Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Roland JC120 (CH doesn´t work)
Since that amp has a stereo chorus and it sounds like neither side is working here’s my best guess as to what’s wrong.
1). The A side of IC5a/b is a 8 pin 2 function IC which is the splitter / input driver to IC6 and IC7, so that’s a pretty good suspect for being bad.
2) Transistor Q18, 19, 21 and D21 control the chorus on/ off function of the foot switch, so any of these semiconductors being bad could kill the chorus .
If the Amps reverb and distortion work, then the basic 15 volt + and - supply is basically ok, but there could be a open power supply resistor feeding that IC5a/b
1). The A side of IC5a/b is a 8 pin 2 function IC which is the splitter / input driver to IC6 and IC7, so that’s a pretty good suspect for being bad.
2) Transistor Q18, 19, 21 and D21 control the chorus on/ off function of the foot switch, so any of these semiconductors being bad could kill the chorus .
If the Amps reverb and distortion work, then the basic 15 volt + and - supply is basically ok, but there could be a open power supply resistor feeding that IC5a/b
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!