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Roland Cube 60 intermittent internal popping

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  • #1

    Roland Cube 60 intermittent internal popping

    Local artist brought in a Roland Cube 60 that has been around. He said there was a problem with the reverb channel, which I later confirmed is what I encountered below.

    I powered it up cold, no instrument plugged in, and turned up the reverb knob and in seconds was random popping/gunshots. It was controllable with reverb control. I turned down the (preamp) volume and the noise continued. When I disconnected the reverb tank output, the noise stopped. Same with disconnect RT input. So it looks like it is coming from the SIP chip amplifier circuit that drives the reverb tank. The problem is, the noise stopped and only occurrs now very sporadically...before I could put a scope on anything. I left it off over the weekend, and today powered it up and it is quiet with a few random pops. I probed, poked, tapped, and nothing will provoke it. I dont have any spray coolant so that will be my next step.

    My thought is, this must be an instance of a generally occurring type of problem with a twenty or thirty something solid state amplifier, whether it be voltage source or signal path issue... Any thoughts or comments would be appreciated. Thanks.
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  • #2
    Why MUST it be?

    No spray chiller? Got some contact cleaner? Any aerosol spray has a chilling effect. Better than nothing.

    Your noise is only in the reverb path. You seem to have isolated it to the drive side. Replace the drive IC, or swap it with another one from the amp. If rep[lacing it works, great. If swapping two around causes the reverb to become OK, but now some other issue pops up, we can assume the old IC was bad.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      "Must" may be too strong, but "usually" or "often" could work in terms of a device failure mode...My thinking is that perhaps it is a capacitor that somehow reforms, then fails, and repeats over a period.

      Problem is the SIP is an oddball that costs around $30 bucks...probably more than the amp is worth. But it belongs to a good customer. We'll get some coolant.

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      • #4
        TA7200p?

        B&D Enterprises seems to have it for $12.

        B&D Enterprises International - Search Results for "ta7200"

        NO chillers? It has a heat sink tab. get a bunch of test lead clips and clip them to the tab. They will act as additional heat sink.

        Your description sounds like a noisy semiconductor. I tend to not think it is caps fooling around, especially at 15v or less.
        Elsewhere, Fahey one suggested it would be simple enough to cobble a TDA2030 in its place.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Yep thats it. B&D didnt come up when I searched. Never heard of them but they appear to take paypal which is handy. Worth a try at !2 bucks. Thanks.

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          • #6
            Hi all,

            I had the exact same problem with a vintage orange Roland cube 60. Turned out to a defect headphone jack. Solved the problem.

            I’ve updated the speaker - I got mine used and with a hifi-type Philips speaker with a soft cone - to an Eminence Beta12. However this speaker lacks warm bass. Maybe it’s noy suited for the small cabinet volume. Any advise from someone? Heard good things about emi cannabis Rex. Opinions?


            Ps: I realize that this is an old thread, but since an answer was never posted, I hope this can be helpful to other forumites.

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