Roland Cube60 problem

[drewl]

So, did we ever come across any schems for the later designed newer Roland cube amps?

Got one that had a bad output amp, replaced it but it still has a strange problem.
It seems to be screwing up the power supply and has noise/hum/DC on the output.
Any ideas? Thanks.

[Enzo]

Is yours different from the one at Schematic Heaven? That is the version in my files.

Isolate the problem, run the pre out somewhere for a listen, and run something into the power amp in for a listen. And scope that power supply.

[drewl]

Thanks, I'll check and see if that's the schem for the Cube60D.

Amp has output up to the headphone jacks, then looks like it runs into a couple little surface mount transistors before hitting the output chip amp Lm3886 i think.
One of the supplies is loaded down a bit and both have a nasty sawtooth from what I remember.
I have to pull the output amp and see, thought I'd get lucky and it'd be fixed when I changed it.

Thanks for the Carvin X100A schem (old 1981 model) in your gallery, a little too late as this site nor ampix were not coming up for me for a few days so I had to fix it without a schem!

[Enzo]

The Cube 60 I have and SH has must be older than yours, there is no 3886 or any sm stuff, just discrete outputs.

[drewl]

Well I pulled out the output amp chip and the power supplies are a nice clean + and - 40v.
Input signal is there, and I have a mute control of -12v....is that correct?
I'm going to check for any wierdness then try another LM3886 amp....maybe I got a bad one or killed it while installing, we'll see.

Thanks.

[drewl]

Okay, found a bad solder trace on the -v input pin of the LM3886 and all's well.

[Enzo]

Schematics? We don't need no steenking schematics.

[drewl]

Had to use the microscope at work....the eyes aren't what they used to be.