Troubleshooting an RE-201 reverb unit

[hovmod]

Hi.
I just got a Roland RE-201 Space Echo in the house, and the reverb unit doesn't work on it. The preamps and tape echo bits are fine. I'm trying to narrow down the problem with the few tools I have, and... well, here's what I did. If someone can look at this and diagnose it I'd be thankful:

I first disconnected the spring reverb tank, and shorted the i/o cables with a double female RCA plug, thus bypassing the tank. This added a noise pulse to the output signal from the 201, and I assume that might tell me that the cables are OK (?).
The pulse disappeared when I disconnected the short. The amplitude of the pulse didn't change when I turned the Rev amp knob, but I guess there's some serious mismatching going on with the rev preamp and the missing coils and whatnot...

I then connected the output from the 201 straight into the reverb unit (using known good cables), and got nothing. Nada. A typical springy boing when I touched it, but nothing went *through* it. There's no preamp or anything, so this might not be a good test. What do I know (this is why I'm asking)?

Is it fair to assume, after such crude tests, that the coil on the input side is broken?

Or do I have to do more sophisticated tests?

Should I expect a good, useful signal from the shorted i/o-cables bypassing the reverb tank when I turn up the rev level?

Please help - the result of this decides whether I keep it or give it back to the seller, who was kind and honest enough to admit he hadn't tested the rev and would take it back rather than pay for repairs. But if I can repair it myself I'd like to keep it...

So. Anyone familiar with this? Am I struggling with a known problem?

Tormod

[52 Bill]

Originally Posted by hovmod

I then connected the output from the 201 straight into the reverb unit (using known good cables), and got nothing. Nada. A typical springy boing when I touched it, but nothing went *through* it. There's no preamp or anything, so this might not be a good test. What do I know (this is why I'm asking)?

Should I expect a good, useful signal from the shorted i/o-cables bypassing the reverb tank when I turn up the rev level?

I'm not sure, but I don't think that jumpering the input to output would give you a clean signal.

The first test would be to plug the tank back into the unit, turn up the reverb control and shake the tank. If you hear the springs boing, then you know that the reverb tank output coil is ok, as well as the return circuit in the 201.

If this checks out so far, then plug in the tank backwards, with the output cable going to the input of the tank. Then shake the tank again. Here you are testing the input coil of the tank. If the coil is ok, then you will still hear the spring boing, just not as strong as when the tank is plugged in correctly.

[hovmod]

OK, thanks a lot.

It didn't make any boings 'in the box', but when I connected the rev unit directly to an amp with nothing else connected, I got boings from both the input and output side.

So I assume the rev unit is OK.

Next I'll replace the cables, then I'm afraid I have to suspect the rev preamp or the output circuitry...

If you know what to do next, please fill me in. I'm in unfamiliar territory...

[52 Bill]

Originally Posted by hovmod

It didn't make any boings 'in the box', but when I connected the rev unit directly to an amp with nothing else connected, I got boings from both the input and output side.

So I assume the rev unit is OK.

Yes, if you got boings from both sides, the tank is ok.

Originally Posted by hovmod

It didn't make any boings 'in the box'...

If it didn't make any sound while in the box, either the return cable is bad/loose or the reverb recovery circuit is not working. Check the cable first, if it isn't the cable, then it will require circuit repair.

[hovmod]

OK, I replaced the cables that run to and from the reverb tank, but no joy. Good tank, good cables, no reverb.

I'm debating whether to try to troubleshoot and fix or to ship it back. If it were my old trusted echo I'd try to repair it, but this is a unit I bought under the impression that it was in working condition, and he's willing to take it back if I don't feel I can fix it.

Any more good advice? What would I need in addition to the service manual and a soldering iron? I assume I'd need a signal generator and a scope plus do some math to figure out what to expect on the various nodes on the card. I feel confident that my findings so far are sound (ironically) and that no harm has come to the unit as a result of my interference, but from here I feel its less safe...