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FDP Forum / Amp Mods, Repairs, and Projects / Roland Cube 60 (SS) Lead channel oddity

archiestone
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El Californio

Jan 28th, 2018 03:15 PM   Edit   Profile   Print Topic   Search Topic

Clean channel works fine, Lead channel locked on one setting (fortunately a usable one - Tweed.) Rotary channel switch won't dial in other amp modes. Vol and gain are working.
I've never had an SS amp problem before -- wouldn't know where to begin. Amp was not dropped or abused so I have no idea why it's doing this.
Any suggestions? Willie?

willie
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Too Near Atlanta GA

Amp Tech Emeritus
Jan 28th, 2018 03:47 PM   Edit   Profile   Print Topic   Search Topic

Is this the Roland Cube 60 COSM model? There have been several Roland Cube model amps...honestly, I have very little bench time on Roland amps over the years. I would suspect that the COSM amps might well be surface mount (SMT) versus the older through hole technology which makes servicing a lot more complex. More than likely there is a switching component that has failed....a JFET or similar. These amps don't lend themselves well to servicing by other than Roland techs...unfortunately. They are well worth repairing though...great amps.

willie

archiestone
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El Californio

Jan 28th, 2018 04:31 PM   Edit   Profile   Print Topic   Search Topic

Thanks, I love it as an office & bedroom amp. Acoustic channel is quite usable too -- when it works! I'll let you know...

(and yes, it's a COSM model.)

(This message was last edited by archiestone at 10:28 PM, Jan 30th, 2018)

Peegoo
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Tried vegetarian:

miss steak.
Jan 28th, 2018 08:40 PM   Edit   Profile   Print Topic   Search Topic

If it has a foot switch jack for switching between clean and lead channels, try plugging a TRS plug into it and see if that changes the behavior.

willie
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Too Near Atlanta GA

Amp Tech Emeritus
Jan 28th, 2018 09:04 PM   Edit   Profile   Print Topic   Search Topic

Good suggestion....

w

archiestone
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El Californio

Jan 30th, 2018 05:54 PM   Edit   Profile   Print Topic   Search Topic

Peegoo, You got me all excited with your suggestion!... but, alas, no change.

Peegoo
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Tried vegetarian:

miss steak.
Jan 30th, 2018 10:55 PM   Edit   Profile   Print Topic   Search Topic

Sometimes the rotary encoders go bad on these things too. Find a Roland service center and get it checked out. These amps rarely go down for service.

willie
Contributing Member
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Too Near Atlanta GA

Amp Tech Emeritus
Jan 31st, 2018 09:24 AM   Edit   Profile   Print Topic   Search Topic

Fact...

w

Leftee
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VA

Life makes a man tired.
Feb 1st, 2018 02:46 PM   Edit   Profile   Print Topic   Search Topic

The rotary encoders on my (now) old PV Vypyr are giving up the ghost. I think it's time to move on.

She served well. I bought it (and the footswitch) cheap from CL.

Next!

archiestone
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El Californio

Feb 8th, 2018 03:50 PM   Edit   Profile   Print Topic   Search Topic

FYI - I took it to a Roland auth repair guy who diagnosed it as requiring a completely new "computer" (his word.) Unfortunately the cost is more than the amp's worth -- but it's still very usable as a 'JC Clean' bedroom amp and the fx still work so I'll just live with it until a used one shows up on local craigs which they do from time to time.

DrGonz78

United States Phx,AZ

Mar 26th, 2018 04:51 AM   Edit   Profile   Print Topic   Search Topic

To me the symptoms explained on this amp point towards a broken switch. I don't buy the amp tech's diagnosis and I would have a closer look at that ch2 rotary switch. The one I fixed had rotary switch where the contact broke loose. In doing so the voltage divider circuit became stuck on the first base voltage. You see as you rotate the switch each turn it has a bank of resistors that alters a voltage, each voltage is a different amp sim setting. You open up the unit and test voltage divider circuit with a voltmeter to see if the switch changes the starting base voltage with each turn. You can also test for continuity of the switch to make sure the contacts are making a connection to the corresponding circuit traces. What happens is the metal contacts on the rotary switch are held to circuit board by supporting plastic part in the switch. When the plastic cracks it can't hold enough pressure to make the metal contacts on the switch touch the circuit board. I literally super glued the little metal contact wiper on the switch, which was not too easy, but the fix has worked 3 years and counting. Probably the best idea is to replace that switch with a brand new one. The reason I posted all this is that I am very confident that the switch is the only problem with your amp.

(This message was last edited by DrGonz78 at 07:05 AM, Mar 26th, 2018)

Steve Dallman

Merrill, Wisconsin

Age is just a number...mine is big
Mar 27th, 2018 07:17 AM   Edit   Profile   Print Topic   Search Topic

I bought a PV Vypyr a year ago, cheap, because the rotary encoders did not work...any of them.

I sprayed the each with cleaner/lubricant and they all work fine. Not a problem since.

I actually was surprised it was this simple and I've been doing amp work for decades.

DrGonz78

United States Phx,AZ

Mar 30th, 2018 01:47 AM   Edit   Profile   Print Topic   Search Topic

Of course this is merely a rotary type switch so yes it can be cleaned off like any old analog switch. Not sure it is same as peavey vyper amp? It is not really an encoder since it is passing merely analog voltages to a multiplexer that sends that to the dsp chip. That's exactly why I don't think dsp is to blame for the failure. Since the dsp is working on the first selection of the voltage divider then I would bet the switch or something related is not functioning correctly. Look at this post from another site for the repair I did.

http://music-electronics-forum.com/t18748/

(This message was last edited by DrGonz78 at 03:48 AM, Mar 30th, 2018)

Leftee
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VA

May 18th, 2018 03:20 PM   Edit   Profile   Print Topic   Search Topic

"I bought a PV Vypyr a year ago, cheap, because the rotary encoders did not work...any of them.

I sprayed the each with cleaner/lubricant and they all work fine. Not a problem since."

I just did this with my old Vypyr. Works like a champ again.

I'm gonna sell it on CL along with the Sanpera I. I really have no room for it.

I stuck a Blue Marvel back in it - one of the speakers from the Special 212 I purchased to replace the Vypyr. I had closed in more of the back of this amp (Vypyr) a while ago. Actually, the BM sounds pretty good in this now.




I said BM

Peegoo
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Always

trust your cape
May 18th, 2018 03:33 PM   Edit   Profile   Print Topic   Search Topic

"I just did this with my old Vypyr. Works like a champ again."

That's weird. A Champ is a completely different amp. Hee hee


Yeah, sell that thing before it gives up the ghost again!

Leftee
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VA

May 18th, 2018 04:09 PM   Edit   Profile   Print Topic   Search Topic

And it doesn’t even have a Champ model in it. ;-p

Leftee
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VA

May 19th, 2018 09:14 AM   Edit   Profile   Print Topic   Search Topic

So... I have a hard time selling anything these days. About a year ago I sold a Celestion V30 on CL because I knew I was never going to use it. I don't even remember what amp I bought it for. Or where it came from. Maybe it came out of an amp or cab.

But dang... if I like something I just can't part with it these days.

I sold a lot of gear in years gone by. Some of it I regret parting with.

[sigh]

If I knock this wall out...

Leftee
Contributing Member
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VA

May 19th, 2018 05:05 PM   Edit   Profile   Print Topic   Search Topic

False alarm. Turns out I had a stacking option I hadn’t considered.

FDP Forum / Amp Mods, Repairs, and Projects / Roland Cube 60 (SS) Lead channel oddity




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