Hello Mr. Roland Sampler, please meet my friend Mr. Color Monitor

Tonight I experienced my Roland S770 sampler in full color, and it was deeply satisfying.

Roland S770 Color

First, a little story, and then I’ll try to give more of the technical details at the end:

Some of the old Roland samplers from the 80s have the luxurious option of a monitor output. On my sampler (the S770), there is both an RCA plug (for monochrome composite video) and a mysterious 8-pin DIN plug that supposedly would provide color video. Getting the monochrome RCA output to work is pretty easy, but I really wanted the color output. I already tried once to wire up a converter and failed miserably. Well, tonight was different.

After my initial failure, I decided to actually order the right parts and do a better job of wiring everything up. I bought an 8-pin DIN plug from Mouser (part 171-0288, to be exact) and picked up some different transistors. I set aside the breadboard and actually soldered everything together this time. The 8-pin DIN plug was a major pain, and the whole thing probably took me a couple hours. I’m very slow at soldering.

I plugged everything in and fired up the sampler with great anticipation:

S770 progress

I guess it was progress, but it was still pretty unusable. I felt a strange confusion of joy and disgust. After checking everything over a couple times and finding it all right, I honestly didn’t know what else to do. But at the same time, I had to admit that I was getting some sort of signal, so the theory behind the whole operation was pretty sound.

I went back and poked around on the circuit board, paying close attention to the wires that fed the horizontal sync. I replaced the transistor but found that the video display was still slanted. I began to lose hope. And with that, I also began to lose caution. At one point I disconnected the little yellow wire that fed my horizontal sync line to the monitor and was connecting and disconnecting it from its transistor. I’m sure that’s a very bad thing to do. At one point I accidentally brushed it against another leg of the transistor and the signal immediately snapped to attention. It was perfect! I was somewhat stunned.

I checked the schematics and found that my “fix” was definitely not in agreement with the official circuit. I didn’t really care though. I wired it up with the wire now touching the other leg of the transistor, plugged everything back in and quickly declared victory before it could stop working:

A happy Roland sampler

This has been a lot of work, but it’s really nice to have the color output. It adds something special to the whole Roland S770 experience. Here are a few more pictures, and then I’ll try to explain whatever technical details I can remember:

S770 Screen 1

S770 Screen 2


Technical Details from Someone Who Just Thoroughly Undermined His Electronics/Circuit Credibility:

The surest way I could find to hook up to Roland’s RGB output is with an old CGA monitor. If you’re in Europe, SCART is supposedly an option. However, I have no idea what SCART is and I’m not in Europe. Also, I happened to have an old CGA monitor laying around the house, so I went with that option. I’m using the super-old IBM 5153 monitor. Folks have reported success with various Commodore or Atari monitors also, but this IBM monitor is all I had. CGA monitors aren’t nearly as common as they once were, but I’m sure they can still be had for very reasonable prices if you watch eBay for a little while. I never see them at thrift stores anymore, sadly.

Information about the Roland sampler video format is scant but not impossible to find. In particular, this thread gave me some hope that it was possible to build an adapter to convert from the Roland output to a CGA input. In particular, they talked about a schematic. I studied the schematic long and hard, through it was a bit blurry. Then one day while I was flipping through my S770 owner’s manual, I found the exact same schematic in the back. So to help anyone out, here are some higher-resolution scans of that video schematic info:

S770 Video Diagram Wiring

Roland S Sample RGB schematics

As I mentioned, I bought the 8-pin DIN plug from Mouser. It feels a little cheap, but it did the trick and I didn’t initially see many alternatives for good 8-pin DIN plugs. The schematic drawing mentions a mysterious “DTC 11 AFE” transistor. I took the advice on that afore-mentioned thread and went with the more common BC550. That worked fine. For the cable, I just lopped off the ends of an old printer cable and used eight of the wires inside. Unlike CGA monitors, old printer cables are in ample supply at the thrift stores. I got the female D-Sub-9 connector for the CGA monitor to plug into at Radio Shack.

That thread mentioned not needing the 1k resistor for the vertical sync. I tested both with and without this resistor and found that it didn’t make a difference, so I left it in.

However, here was my change to the circuit that proved critical in getting it to work with my adapter. I have no idea if this is applicable to other monitors, but I know it was needed for my IBM 5153. Instead of connecting pin 4 on the DIN plug (the “H” line on the schematic) to the base of the transistor, I basically bypassed the transistor and just wired the straight into pin 8 on the CGA monitor’s D-sub connector. I’m not sure what I did there, but I’m not going to argue with a nice-looking color display on my monitor.

The only thing that isn’t working well is the horizontal offset on the screen. It’s just a little too far to the right, probably by about half an inch. Unfortunately, my monitor doesn’t let me adjust this. I’m not sure if there’s something I can do to the circuit or if I’m just stuck like this. However, it’s still very legible and I’m tired of working on the circuit instead of actually using the sampler, so I think I’ll just let this horizontal offset issue slide.

Anyway, here’s the final product. Please ignore those three op amps on the side. They were the beginnings of another project on that circuit board from years ago and I was too lazy to unsolder them. Despite several hours of soldering, it’s pretty messy, and it still looks pretty crappy. But I’ll throw it in a little case and forget about all that while I happily use the new color display on my Roland sampler.

S770 video converter

Teaching an 808 some new tricks

TR-808 and Korg KMS

I’ve been really happy with my Roland TR-808 ever since I got it a year or so ago. I bought it because I thought it would magically solve my inability to make good drum patterns. Percussion has been a weak point for me, and I thought that maybe I needed a better tool.

I first tried using a TR-707. It’s much cheaper than an 808 and yet it’s got a really useful-looking matrix that shows the drum pattern for all the different drum sounds at once. I thought that a visual aide was just what I needed. But it turns out that the 707 doesn’t let you change the pattern while it’s in the middle of playing. This was a major blow, since I wanted to be able to experiment with the pattern while it was playing.

So I eventually shelled out and just got an 808. It’s very simple and intuitive to program, which is exactly what a rhythm dullard like me needs. However, I confess that despite my satisfaction with the 808, I have found myself staring longfully at some of the other drum machines from the 80s. Sequential Circuits’ Drumtraks, the TOM, the Oberheim DSX or DX, E-mu’s Drumulator. The list goes on (though that is mostly it for me). However, these are all just drum machines with digital samples. I didn’t like the idea of amassing a bunch of drum machines (no matter how nice they look…and they do look very nice) just to access the samples. Yeah, I know that some of them have analog filters. Well, I also have samplers with analog filters. Problem solved. Almost.

I still liked the 808’s method of programming patterns. The best world would be to use the 808 but have some additional sounds. The 808 has three trigger outputs, and these could potentially be used to trigger other devices. But I usually want more than 3 sounds in a pattern. Instead of using the trigger outputs, I decided to run the individual audio outputs from the 808 through a box that would convert them to MIDI notes.

808 outputs

I first tried using an Alesis D4 to convert the audio into a MIDI signal. I always thought of the D4 as just a way to get some cheap drum sounds, but it’s also got a ton of trigger inputs. Alesis intended for folks to hook up drum pads to these trigger inputs, but it supposedly also accepted regular audio as triggers.

The D4 didn’t work so well at converting audio into MIDI. It worked ok on certain sounds, but less reliably on other sounds. I could never get it to convert the hi-hat sound, for example. I didn’t have much patience for the D4, and an Akai ME35T popped up on eBay for cheap. I actually meant to bid on the auction and then got busy and accidentally forgot about it. But luckily no one else bid on it and the seller relisted it. Hurray! Plus, I just think Akai gear looks nicer than Alesis stuff.

Alesis D4

The Akai worked like a charm, and it was also much easier to configure all the various triggers than the D4. Eventually my master plan is to sample various drum machines and build up a library for either my ASR-10 sampler or the Emulator III. In the meantime, I hooked the MIDI output on the Akai ME35T into the D4 and just used the stock sounds on the D4. It’s got a variety of classy-sounding 80s drum kits that are fun to switch through. Anyway, I made a little demo of the process:


[pro-player TYPE=”MP3″  image=”http://thecompleatsynthesizer.com/media/images/808.jpg”]http://thecompleatsynthesizer.com/media/audio/tr808triggerdemo.mp3[/pro-player]

It lives! It lives, it lives, it lives!!!

The Emulator III has returned! As of this afternoon it is now back in working condition!

How did this happen? Well gather round and let me tell you about today’s serendipitous events. It all started when I noticed a closed auction for sampler memory for Roland samplers. As I’ve thoroughly documented, I’ve got a Roland S770 that I’m going to keep, but I’d really like to max out its memory to a full 16MB. The memory that it takes is pretty old and not the easiest to find. The auction reminded me that I really should buy some memory and get it installed. I found a few auctions that were promising candidates, but I was still a bit unsure and decided to open my S770 and closely inspect some of the memory that was already in there.

As I was searching for information, I found a page that claimed that the E-mu EIII used the exact same memory as the S770. That got me thinking…maybe the EIII’s cryptic problem was just an issue with faulty memory? That would be easy to check! With the S770 opened up, I had some spare sticks of memory that I knew were good. This would be a great time to check. Soon I left the S770 behind and was on a rabbit trail tearing apart the EIII.

The EIII is a beast inside. The rackmount version has five long cards that slide into place. I had to take out the processor card in order to get the memory card out. Once out, I swapped out the SIMM sticks and put it all back together. And…

…nothing. It still didn’t work. Except this time, I didn’t even have funny characters on the screen. I had nothing at all. It wasn’t trying to check the floppy drive or anything. That’s when I started thinking about a post I’d read on an excellent E-mu website called eiiiforum.com. That post had talked about having a dead display when you try to power up the sampler. The cause was some errant voltages coming from the power supply.

Power supplies generally scare me. That’s probably cause I assume that all power supply problems are going to mean burnt-up transformers or dried-out capacitors. But things were different in this case. The EIII’s power supply has a small trimmer pot that allows you to adjust the output voltage. For some reason it can stray slightly, and that can lead the entire machine to crash. So I pulled out my multimeter and checked. Sure enough…the voltage was about 1 volt too low – enough to put it out-of-tolerance.

I followed the steps in the post and reset the voltage to 5.05 volts exactly, plugged everything back in, and it’s back in business! Such an easy fix! And to think that I’d been dreading that for months!

I’m really excited to have the EIII back and working. The 2012 Ultimate Sampler Showdown is back on!

I’ll leave you with this parting photograph. I think that the back of the EIII is pretty impressive. There really is nothing about this sampler that leaves you doubting that it means business. I don’t think I’ve seen quite this many jacks on a piece of equipment. Clearly, a formidable instrument:

One of these days…

… I’ll learn that there is no prize for collecting the most samplers. Here’s the latest, an Ensoniq ASR-10 rackmount:

I picked it up in Minneapolis when I was out visiting my brother. Anytime I find myself in The Big City (these days that means either Chicago or Minneapolis) I take advantage of the better Craigslist listings there. Usually I don’t find anything interesting. Even when I do find something, it’s a crapshoot. This ASR-10 fit that definition exactly.

Like a computer it needs to load an operating system for it to actually work. Unlike most computers, it doesn’t have a built-in hard drive. Built-in drives didn’t consistently start appearing in samplers until the mid 90s. Nobody knew it at the time, but by then samplers had already passed their zenith by then. Back to the story:

The seller wasn’t sure it it actually worked since he didn’t have the operating system disk. I thought I could be clever and show up with a working disk. My brother had a spare 3.5″ USB floppy drive, and he even had some spare disks. Pretty impressive inventory for 2012, I’ll say! But it turns out that the ASR-10 disk format is exceptionally unique. It is possible for a regular computer to write disks in this format, but the computer has to actually be running Windows 98 or something older for this particular utility to run right. So I decided to just show up and check it out in person.

The guy was really nice and although he didn’t actually play synths or know how to use it, he tried to do his homework. I spied a to-do list sitting on his kitchen table that included a note to check out the EPSDisk utility. I feel your pain, brother. Anyway, the thing powered up, and I was in a gambling mood so I bought it. Once I got back home to Michigan, I was able to use a venerable 486 running Windows 98 to create the disk. And the ASR-10 works! So why another sampler? Coming up next!