ELKA Piano 88

[Jazz P Bass]

Customer brought in a Elka Piano 88.
Made in Italy.
Looks old.
Anyone have a schematic for this jewel?

[Enzo]

Hah!

What does it need?

[Enzo]

And might be more response at one of the vintage synth forums, but we can try to help.

[Jazz P Bass]

Well, it looks like it has two very vintage power supplies.
-40 & -17 Vdc. The -17 had a blown 500ma fuse.
I resoldered the power supplies. They are good.
There is one note that is always on & two keys that do not output a note.
Enzo, by your response I take it you have crossed paths with this black cat before.

[Enzo]

Honestly I don't even remember. I have worked on a variety of old analog pianos over the years. To me circuits are circuits, so I just dig in to whatever shows up on the bench.

Does this one have a whole row of circuits running the length of the keys? A small transistor circuit for each note? If the key contact is not stuck shut - check first - then I'd look for a shorted transistor sticking the note on.

Dead keys? First thing is check the key contacts. If there is a row of diodes with the key contacts, check for a bad diode.


Now I may be thinking of a totally different unit from what you have.

[Jazz P Bass]

BINGO, Enzo.
Same circuit.
Do you have anything even close as far as a schematic goes.
Looks like some kind of matrix setup.
I don't recognize the IC's at all.
Of coarse I did not resrach it yet, I am stuck on a QSC USA 850.

[Enzo]

Well, the QSC will probably be a bunch of bad transistors and a couple open resistors, and perhaps a bad hum balance trim pot.

If you have 88 copies of the same little key envelope circuit. Determine which one belongs to your stuck note. They should be in order up the board, so if it is the 34th key, look for the 34th circuit. I'd be thinking some voltage would look different on that circuit compared to the ones around it. My guts generally would lead me to look for a transistor that gave up.

Google "elka schematic" I did and found this right away. ANy similarity?
http://manuals.fdiskc.com/flat/Elka%...0Schematic.pdf

[Jazz P Bass]

Well, the Elka has a bad IC. TMS3612 7 stage divider.
Probably what took out the 500ma fuse on the -18 volt rail.
I found a replacement KS-180 that has a different pinout.
It comes with a small board to reconfigure the pins.
(Sounds like Peavey).

Anyway the QSC had a shorted PNP output transistor & it's driver.
What a joy. All it took out was the fuse! (Hello Beheringer!!)
Got replacements from QSC. All is fine.