Something a little different today, two retro music oddities from Yamaha.
The 1987 Yamaha SHS-10 (aka "Sholky") and the 1990 QY-10.
Two very different marketing directions (the 'rugged' leather for the QY-10 has a lot to say) but both can run on batteries and both have MIDI support. Combining them makes a surprisingly capable portable audio workstation for the price of a single cable and a quarter kilo of AAs.
Although the Sholky isn't part of the Portasound family it still uses the same OPL FM chip you might know from the SoundBlaster 16. The QY-10 is more of a 'rompler' and uses a bank of samples for each instrument. A really great example of how quickly tech moved in the '80s and '90s.
Unfortunately my Sholky only runs off a power adapter right now so I need to do some repairs to get it portable.
Repair pics under the cut.
First off, here it is in one piece.
I love how the text is facing in every direction, just a really fun design choice. As the keytarist you can read all the buttons but the audience gets a nice big logo to enjoy.
There's no conductivity between the battery terminal, even after cleaning off some battery goop with vinegar, so it needs to be opened up and checked closer.
Inside we have the main PCB. The big chip on the green side is a gate array, the sound generator is the second smallest chip on the beige side.
This is what it's all about, the Yamaha 2420. Apparently a variant of the 2413 aka OPLL. If you've ever enjoyed the classic FM MIDI sound of a SoundBlaster 16 this is the source. I've literally built an entire desktop computer just to control this single chip before but that's for a different post.
Close up on some of the other chips. We've got some Mitsubishi CMOS RAM (smallest chip), a Yamaha ROM, and a Yamaha CPU (largest chip). I couldn't find any info on the two Yamaha chips other than a fantastic circuit bending write up:
Many thanks to the author Christian Windler Oliver. Apparently also the "teachmaster" of Logologie, the first cyberage religion. The details are mostly in German but I'll need to explore that further...
In the meantime my Sholky runs on mains power so I know the issue is somewhere near the battery terminals. Testing conductivity pretty quickly reveals the terminals are the problem and now that they're out of the case I can see the corrosion was much worse than I thought.
Some sandpaper, more vinegar and alcohol and it's back in working order! Taking out the PCB ended up being pointless but at least I got to see the main sound chip.
Quick reassembly and here it is hooked up to the QY-10. Only three years apart but two very different aesthetics. Also, both were released before the General MIDI specification was published in 1991 so it was a nice surprise to find the Sholky's was already on the right channel to control the QY-10's lead instrument.
