Working on music takes a good deal of persistence. Stuff generally just doesn’t work. That applies to both musical ideas (I can’t count how many times I’ve written up a supposedly great counterpoint line only to find that it clashed badly with the melody) and with the technical side (the extremely fickle Emulator III is back in the non-working camp). Part of the difficulty in sitting down to work on music is coaxing myself past the knowledge that what I produce this evening is probably going to be crap. No, really. I’m not being coyly modest. My ears have heard things that sound very, very bad, coming straight out of my very own synthesizers. But the only way forward to better songs is through the slough of cheesy, disinteresting, annoying and unoriginal song ideas. In honor of that, I present the latest mis-attempt: wiring up a monitor output for my Roland sampler.
The Roland samplers from the mid 80s (the S-550, S-750 and S-770) are a pretty cool bargain right now. They all sell for less than $150 and they’ve got some cool features. One of those features is a monitor output, a rarity for music equipment in the 80s. They actually have two monitor output jacks on them. One is an RCA jack and it’s really easy to hook it up to most TVs. Most tube TVs since the 90s have a composite RCA video input (color-coded yellow). This is very fool-proof, but sadly the display is monochrome. You just get black and white or blue and white or whatever the TV decides to do.
The other output is a “digital RGB” output, and it offers that elusive possibility of color output. I’ve wadded through many forums and read contracted arguments over what this term exactly means, and what standard it ascribes to. Roland apparently made a monitor that was perfectly compatible, but it has been wiped off the face of the earth. My friend Jacob has been a quest for this holy grail of monitors and can scour up only a few ad promo photos. In the absence of this monitor, people have devised several ways to convert the output to VGA, CGA, SCART and who knows what else. I surveyed the mess and decided that the easiest thing would be to hook it up to my old IBM CGA monitor.
The circuit is supposed to be pretty easy: just a handful of resistors and two transistors. Roland includes a schematic in the back of the sampler’s manual for the “RGB-25I” cable, and I think this is supposed to be compatible with CGA monitors. The transistors are labelled DTC 11 AFE. I have no idea what that means. So I tried standard 3904 NPN transistors. The trickiest part is actually the connections. The plug for the sampler is an eight pin DIN plug, which isn’t very common anymore. I found some plugs on Mouser but I wanted to test out the circuit immediately, so I just stuck wires into the appropriate holes in the DIN jack. On the monitor side, I needed a female DB25 plug, which I picked up at Radio Shack. An hour or so later and I had this unholy mess:
Yeah, it’s pretty shameful. Yeah, it actually took about an hour. I’m a little slow.
Eagerly, I switched on the sampler and the monitor and found…
…nothing. Just a quiet, very blue monitor. It’s an attractive blue but sadly, a non-working blue. I checked my circuit a little more to no avail.
But I threw this together in such a slip-shod way that I actually would have been more surprised if it had worked. Come on! Wires in the DIN socket? Masking tape to keep the resistors insulated from one another? So I’m just going to do this the right way now: order up the actual plug online, and solder everything onto a real board. It’ll take a little more work, but hopefully I’ll soon have a post about a working color monitor output for my Roland S-770.