S-330 Sampler Repair

I recently bought two Roland S-330 Samplers from a fellow musician at a synthesizer meeting for a reasonable price. Two things made me take them: Firstly, I´ve never owned a Roland S-series sampler and secondly one of them was declared defective. So that rose my ambition to get it fixed. And oh was I surprised about what was the cause of the error!

The previous owner told me that, when switching the unit on, the only thing happening was the LED of the disk drive lighting up. My initial thought was well, at least it still does something, so it can´t be too bad…

Checking it myself I also noticed that the Roll button LED was blinking very fast, and it was not a random flicker. It looked more like a clock-driven reset. My first assumption was that many times there is something wrong with the power supply, in a manner that, at a certain point of the boot process, the unit would draw so much current that a defective PSU would drop in voltage, thus causing a reset and put the unit into an infinite loop. So I was getting ready to recap the PSU but all voltages measured just fine, even under load. Also, all parts really looked okay, so it had to be something else.

So I dismounted the mainboard, performed a visual check of the top side and everything looked fine. Then I flipped it around to check for dull solder pads. And it was not very long until I discovered this:

S-330 mainboard w. troubling wire

S-330 mainboard with troubling wire

If you find it hard to locate it then maybe beauce someone used a blank piece of wire to bridge two points on the board. It was drawn between a pin of the floppy controller to an output of a transistor array. Maybe some kind of pull-up hijacking to fix an unreliable DMA controller. To be honest I did not investigate any further, because it was quite obvious that blank wire across the mainboard touching at least four other pins that where most likely not meant to be part of the equation would cause some sort of trouble… I could imagine that at the beginning this wire was arranged in such a way that it didn´t touch any other pin, but eventually did so, caused by bumps or similar movement. I really can´t believe that someone did this and then said ‘well, I tried something but it didn´t work’!

So at the end a simple fix. Replaced the short-cutter with an isolated wire and, surprise surprise… a working unit! And this one is even in better condition than the unit that was working all along, and to no surprise. Probably the faulty unit has been sitting in a rack unused long enough to prevent some parts from wearing out. The display is still bright like on the first day and the disk drive runs smoothely compared to the ‘ever working’ unit.

But I´m not going to stop here. I am planning on getting one of these MSX to USB adaptors for easy control of the unit. And also there is a schematic for a Roland DIN to VGA adaptor (Roland RGB-25I adaptor cable), so I want to try that out and see if I can hook the unit up to a standard flat screen.

Red Glue Problem

Some older Roland keyboards suffer from a bad choice of material. The metal  plates that give weight to the keys are glued in with a red substance that eventually looses its consistency and drips onto the keybed. Roland did offer a replacement for applicable devices, but it appears that they are now out of stock and can therefor no longer provide that service. Affected devices are mainly JD-800 and D-70. Both my units were affected so I had to come up with a solution. Fortunately not much harm has been done yet so I just had to do a little cleaning.

Here is an image where you can see what it looks like when the glue starts to flow

JD-800 bad key

On the next picture you can see the consistency that it takes on. I used a screwdriver to push back or scrape off the red stuff on seriously affected keys.

JD-800 key scrapeoff

I then took a hot glue gun and sealed the red glue along the edges. This should prevent it from flowing. At least I haven´t experienced any leakage again since then.

JD-800 bad key sealed

The whole procedure took a good hour and about ten sticks of hot glue as the black keys need a little more filling.

KORG M1 realtime control

I never thought I´d ever own a KORG M1. But when I recently found a used one at a very reasonable price I couldn´t resist. Now I am not really interested in its famous piano or organ sounds, or the internal sequencer for that matter. I rather want to explore its capabilities to produce drone like soundscapes. And for that, at least a little amount of realtime controllability would be apreciated.
Fortunately all relevant parameters are editable via SysEx. And as I found out the M1 reacts fluently to parameter changes. The only oddity is that the parameter numbers in the SysEx message depend on the structure of the program, and so double oscillator programs have a different parameterset than single programs. I therefore settled for a control set for double oscillator programs as polyphony is not an issue for me. The fact that the display of the M1 also jumps to the currently modified parameter is a nice touch as well…