Ages ago I’d read that there were originally going to be more modules in the original Roland System 100 series, but nothing further was released (probably in Gordon Reid’s excellent History of Roland)

I hadn’t seen anything more about this until I spotted this brochure on eBay (long gone now) for the original units, with the following:

Also planned for the near future are: Audio Delay unit, Stereo Phaser, VCO bank, and other units.

…so maybe, 105 Audio Delay, 106 Stereo Phaser and 107 VCO Bank?

I could imagine the delay and the phaser being similar circuits to the equivalents in the 700, but I can’t think how they would have been designed to stack up on the System 100 – the top of the 102 isn’t particularly deep. Maybe this was part of the reasoning that led them to design the 100m?

While making a godawful racket with the System 100 on Saturday, I switched to PWM on the 102 VCO and the pulse width stayed unmodulated. The LFO light didn’t light, no matter how much I waggled the slider. Hmph.

Should be easy to sort out a broken LFO, right? I’ve built all the bits of a 102 on stripboard, so surely I should be able to fix it?

Fretting that it wouldn’t be as easy as all that, I peered at the schematic.

None of the outputs were working, so I reckoned the problem was in the tri-core, either the capacitor or the op-amp. Just to check, I measured the output of IC301, and it was pinned high.

At this point feeling strangely optimistic, I enlisted the help of my son, who was bored enough to come and watch/help/encourage/take the piss as appropriate. Is dad gonna be able to fix this thing?

I yanked out the CA1458G in IC301 with a desoldering gun:

I bunged a socket in, and replaced it with an MC1458 I had in the bits box. So far, so good.

Switched it on, and…

…it worked straight-away. WHOOOP.

I probably should have measured all the voltages and given it a bit of a once-over before I put it all back together, but my son was keen to start making some horrible noises, so I just had time for a couple of slightly wobbly bonus photos: here’s the VCO board – see all the keyboard specific components left unpopulated:

and here’s the ring-mod/S&H board

It’s missing the circuit board annotations that my 101 keyboard has, and the soldering on the back is without solder resist (more like earlier System 700s, or my SH-5). The serial number starts with 46, so according to that Boss serial number lookup chart, it was made in May 1976. My 101 keyboard serial is 60xxxx, which works out to be July 1977.

Here’s my Sys101 VCF/VCA for comparison.

I’ve not gone over the board to see if there are any differences in terms of components; there’s nothing extra soldered on to the back of the 102 VCF/VCA board, which suggests probably not. I pulled out the circuit board for my 104 sequencer recently, and it has a different circuit board layout to the one in the manual, with a load of bodged extra capacitors soldered to the back.

So, er, to cut a not-particularly long story short, I bought a System 100 102 expander a while back. It came with a 104 sequencer for an only-slightly-outrageous price, so I decided to have it. After all that faffing with trying to clone one, as well.

I’ve had fun playing with it in the little time I’ve had, there’s been lots going on this year.

It seems like there aren’t any going spare on the internet so I’ve drawn up a patch sheet for the 101 and 102, here it is:

system100patchsheet20151014

While we’re at it I’ve been peering at the “Being Boiled” patch sheets that Martyn Ware flashed up in various YouTube videos, here’s my attempt:

…and this is what it sounds like, with extra dicking around. Don’t get your hopes up.

…yeah, I know it doesn’t really sound much like the original record, but that’s what was written down, as far as I can tell.

I can’t think that over thirty years of aging components would have that much of a difference, so I suspect there was something else going on in the mix, maybe Ian Craig Marsh’s second 102 was involved.

Who cares anyway, it taught me that the CV timing input on the 104 sequencer is a fun thing to be used.

Update April 2023
Alex Ball just posted his excellent overview of the System 100, and it includes his attempt at the Being Boiled beat which sounds spot on, so go and listen to that instead of my wonky twiddling.