ROLAND JC120

[69tele]

Hi folks.. hope you guys can help out

Have my dads Roland JC120 in for repair as he is getting a very flat sound.

He's "repaired" the speaker leads (soldered them !) and I think he may have connected them incorrectly.

If anyone has an early JC120 would they be able to post a pic of how they should go ?

At the moment both speakers work, the main channel sounds very flat and has no reverb.

Thanks in advance !

[52 Bill]

He's "repaired" the speaker leads (soldered them !) and I think he may have connected them incorrectly.

The black and brown wires are the grounds from the right and left channels, so they should both go to the same side speaker terminal. So, switch the wires on one of the speakers and you should be good to go.

The reverb only works on the chorus channel.

[Fragger]

I went out to the net and found a picture of a working JC120 for sale. It agrees with what 52 Bill said.

[69tele]

Thanks guys ! seems to have done the trick

reverb still not working on the main channel though, get noises from the tank when I move it but no reverb when the pot is opened up

[Leo_Gnardo]

get noises from the tank when I move it but no reverb when the pot is opened up

Test tank output for @ 200 ohms. If it reads open, pull out the tank and have a look inside. There may be a broken lead from the output connector to transducer. If that's the case, and you can re connect the tiny wire, you're back in business.

[52 Bill]

Test tank output for @ 200 ohms. If it reads open, pull out the tank and have a look inside. There may be a broken lead from the output connector to transducer. If that's the case, and you can re connect the tiny wire, you're back in business.

I would think just the opposite. If the amp is making spring noises when the tank is shaken, the output transducer is probably okay.

Check the connections to the tank, and as Leo suggested, check the small wires inside the tank itself. The JC-120 used a number of different brands of tanks, OC, Accutronics, etc. They all work on the same principle, and they all fail fairly regularly.

[Leo_Gnardo]

I would think just the opposite. If the amp is making spring noises when the tank is shaken, the output transducer is probably okay.

Check the connections to the tank, and as Leo suggested, check the small wires inside the tank itself. The JC-120 used a number of different brands of tanks, OC, Accutronics, etc. They all work on the same principle, and they all fail fairly regularly.

The way I read it, 69tele can hear the springs sproinging around in the tank box, but not thru the amp. I could be wrong. 69tele will need to clarify. Either way a look inside the tank may reveal the problem. And if need be, replacement tanks can be had from several sources including Antique Electronics.

[69tele]

Guys thanks for your help it was just a loose wire to the RCA connector into the tank ... wire is very tight on length though so had to do it in situ .. all sorted now !