Saturday, June 30, 2012

Polysix finally gets MIDIfied

After a long wait, the Polysix has gotten the CHD Elektroservice MIDI retrofit kit installed! :)

Actually, I installed it a couple of days after installing the Poly-61 kit.

However, I couldn't get this Polysix kit to work straight away!
Knowing that my Polysix has had some problems in the past, I wasn't sure what caused it.

Depeche Mode - Tora! Tora! Tora! (Cover by me)

I just thought I'd make a link to a youtube upload I made a couple of weeks ago.
It's a cover of the Depeche Mode song "Tora! Tora! Tora!" which I recorded about a year ago.

I'm not too happy with the kick (sounds weak) and the spooky theremin-like sound in the chorus could've been a bit louder.
Other than that I guess it's alright :)

Here it is:

Again there is a soundcloud alternative if you prefer:

Saturday, June 2, 2012

TC5514APL-3 SRAM tester

Ok, this may seem a bit silly...
I recently purchased a tube with 20 pieces of TC5514APL-3 1024x4bit SRAM.
That's 4kbit, or 512 bytes if you will... Access time 300ns.
It's an 18-pin DIP chip.
Why would anybody want an old crappy memory like that?
Well because it's used in some old synthesizers of course!

As far as I know, it's used in the Korg Polysix (that I own) and the Korg MonoPoly.
Probably more machines than that. Or at least it might be possible to use it as replacement for other similar memory chips in other synthesizers.

Aaanyway... How do I make sure they work?
I don't want to open my Polysix, remove my chip, put a socket in its place and use the Polysix as a testbed for them. Also, that's not a fun way to test them.
Now I have an excuse to start yet another project: The TC5514APL-3 tester! :)

Replaced Prophet 2002 data potentiometer.

This is so stupid...
Whyyyyy!? Sequential Circuits Inc...
They like pissing people off by using potentiometers that are ever so slightly smaller than your standard off-the-shelf potentiometers.
They're called R-235 and seem to be linear 10k potentiometers.
Here are the measurements I got (using a caliper) from the one I removed.

Matrix-6 volume board (incl slider) replaced.

After giving up trying to find a replacement slide potentiometer that fits the Matrix-6, in combination with the awful condition of the small board the slider is mounted on, I found an old board for sale at .

They know how to charge for their parts but I figured it has been long enough without any other solution.
So, I ordered the volume board, took the old one out, installed the new one...