Picked up what I hope will be a bit of a bargain on eBay, the Kurzweil 900 MX MicroExpander.

There’s not a lot of information out there, but I believe it was launched in 1989 as part of their Home Product range and features 63 sounds taken from their flagship K250 including pianos, bass and strings. Being a home product, there are some compromises such as using phono plugs rather than 6.5mm jacks and having a wall wart power supply rather than a built in PSU, but it does retain the 12 note polyphony of its older sibling.

This particular unit looked a little worse for wear on eBay, with some scratches on the top and no power supply. It didn’t look too bad when it arrived today though, but I had no idea if it would actually work.

Connecting a spare 9V AC PSU, the MIDI light flashed on for a second, but it appeared the backlight on the LCD was dead. I could just about read the text though and navigate through the sounds – so far so good.

The 900 MX uses a 16 character, single-line LCD so I set about sourcing a replacement, finally settling on a Winstar WH1601 which you can find on eBay. Unlike my Akai S2000, the LCD isn’t wired directly to the circuit board, so this should make it much easier to swap out. I’ll follow up with more details once I get the LCD replaced, but for now, check out this video from Espen Kraft where he demos the similar 1000 PX

Update 8/1/2021

Still waiting for the replacement LCD, but it has at least shipped now so should arrive next week. Meanwhile, I’ve started reviewing the pinouts on the old LCD as it’s in 2 rows of 7 pins (plus separate pins for the backlight) rather than a single row of 16 as is on the replacement.

This website has been quite illuminating (pardon the pun) and revealed that the pins are numbered in pairs.

LCD 101 – https://www.spikenzielabs.com/learn/lcd_how_to.html