Roland Drum Machine Repair?

JezWynd · March 2018

I have a problem with my CR-68 ComuRhythm. The Variation function does not seem to be working, or rather, it seems to be locked into that function so that it's constantly playing a variation rather than the basic beat. Setting it to Auto or Manual and using the external switch all have no effect. It's something that I could live with but I'd like to get it repaired if at all possible.

Is there anyone with knowledge of these boxes who could suggest something I could possibly do (I have contact cleaner but soldering is beyond me). Or else, is there anyone out there who can fix these things? Thanks for any advice.

Funkfingers · March 2018

The unit is repairable.

Open the box. Take a look at all of the connectors on the inside of the front panel. Something may have worked loose.

The likeliest point of failure is the Variation push button itself. It may have failed mechanically. The solder joints may have dried.

JezWynd · March 2018

Funkfingers said:

The unit is repairable.

Open the box. Take a look at all of the connectors on the inside of the front panel. Something may have worked loose.

The likeliest point of failure is the Variation push button itself. It may have failed mechanically. The solder joints may have dried.

Thanks for the advice. I know enough to reflow the solder joints (i think!). If the push button has failed, would that disable the footswitch (1/4" jack socket on rear)?

goldtop · March 2018

If all else fails, Synth Prof (in Suffolk/Essex). As FF says - definitely repairable.

Danny1969 · March 2018

Generally you can test the switch by working out which contacts are supposed to be made or breaked and then use a meter to confirm it is doing so. Often in a given piece of kit the same kind of switch will be used more than once so that can help if you need a good working example. Sometimes what looks like a big chunky switch is just something pushing against a far smaller micro switch on a PCB and this is a common point of failure

If it's a push to make flip flop switching circuit than a switch failed in the on state could well cause the external foot switch to become ineffective as it can't change the first condition

JezWynd · March 2018

Thanks for the responses. I did take it out of the case to see if there was a loose joint and took the opportunity to wave some canned air around and spray contact cleaner on the switch in question without success.

Thanks @goldtop,I've sent a message to Synth Prof as there is another fault in addition to the Variation button - the A/B switch is not doing its job, plus I don't think the drum sounds are quite as good as the TR-66 I have, so it would probably benefit from a full service.

@Danny1969, there is indeed an identical button to the Variation button, the Start button, and I did consider swapping them around but it would mean disassembling the whole board which is beyond me tbh and would likely result in more damage. I'll leave it to the experts.

frank1985 · March 2018

That is such a classic DM. Have you owned it from new? CR78 is my fave of the lot, it has the best snare sound of any drum machine I’ve heard

JezWynd · March 2018

frank1985 said:

That is such a classic DM. Have you owned it from new? CR78 is my fave of the lot, it has the best snare sound of any drum machine I’ve heard

I picked it up on eBay about 18 months ago but it's spent a lot of time since sitting in storage. I've only recently had an opportunity to give it a thorough workout. I love these old drum boxes, the TR-66 Rhythm Arranger, in spite of being very basic, is my favorite. As I understand it, all three, TR-66, CR-68 and 78 all have the same drum sounds though the 78 has a couple of additional percussion sounds in addition to its programming ability. After 30 years there's usually some drift in component values so short of getting one that's been fully serviced, it's a matter of luck if you find a good one. Run them into a delay unit and they start to get very funky...

johnnycashsboots · May 2018

Yeah I love the 68/ 78 snare too although prefer the 808/909 programability... James Walker at Synth repair services in Stoke is my go to guy. Lovely fella and what he doesn't know about old synths drum machines etc ain't worth knowing

JezWynd · May 2018

johnnycashsboots said:

Yeah I love the 68/ 78 snare too although prefer the 808/909 programability... James Walker at Synth repair services in Stoke is my go to guy. Lovely fella and what he doesn't know about old synths drum machines etc ain't worth knowing

Thanks for the info, I've sent him a message to see if he could assist.

HarrySeven · May 2018

johnnycashsboots said:

James Walker at Synth repair services in Stoke is my go to guy. Lovely fella and what he doesn't know about old synths drum machines etc ain't worth knowing

I'll second that!

jonnyburgo · May 2018

Wir fahren fahren fahren auf der Autobahn.

Funkfingers · July 2018

@JezWynd Any news on the CR-68 repair?

JezWynd · July 2018

Funkfingers said:

@JezWynd Any news on the CR-68 repair?

I sent a bunch of messages to different technicians and only a couple responded and then with high repair fees. In the end I sold it "as is". I still have the TR-66 which was always my preferred model despite its simplicity. I think more generally that I'm done with vintage drum machines; not having the ability to do my own servicing and. with their ageing likely to reveal new problems it's not a field that I can afford to stay in. Thankfully, the TR-66 is proving very reliable and its simplicity means there's less to go wrong. Fingers crossed.

Funkfingers · July 2018

Sad but entirely understandable.

HarrySeven · July 2018

JezWynd said:

In the end I sold it "as is".

Bollocks. Had I known, I would have bought it.

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