"Josh9.0" <squalene...@hotmail.com> wrote in message

> Hi.
> I recently bought a 2nd-hand Roland HP-860 electronic piano (88-key,
> analogue).
> It has a louder hum than the piano notes.

> I'd like to fix it myself. I have been learning electronics most of my
> life & I'm in the 3rd year of Electronics Trades at TAFE NSW
> (Australia).

> I've removed the plug from the final stage PCB (Revo board), and the
> amplifier is quiet. This makes me think that somewhere before the amp,
> there is hum being made.
> I could poke around with my CRO, but I wouldn't know what to look for.

> This piano has heaps of boards, for which I've worked out most of the
> features.

> I could try replacing all the aluminum electrolytic caps, but that
> could just be a waste of time.
> It was made some where between the late 70's and early 80's.

> I looked for date codes, and only found 1, I think.

> This piano uses a wiring loom design, with some PCBs using plugs, but
> most are wired up (soldered).

> To see pics of it, search Google images for
> "roland hp-860"
> use quotes and thaisecondhand.com has the pictures.
> NOTE: I have the 240VAC version.

> Please help! :)
> TIA