Category Archives: Sampler

Roland S-330 power cable replacement

Lately my Roland S-330 sometimes hasn’t started when I’ve pushed the power button on the front. I’ve noticed that if I moved the power cable downwards it powered on, although a bit glitchy if I didn’t pull it hard enough. So when I had the S-330 out of rack I opened it up to see if everything looked alright near the power supply. And everything did, the soldering looked perfect. Moving the power cable made it turn on and off. I reckoned there must be some kind of breakage in the power cable, probably where the cable goes of the case.

I've unscrewed the metal plate in which a plastic part is mounted through which the power cable goes.
I’ve unscrewed the metal plate in which a plastic part is mounted through which the power cable goes.

As you can see the cable is run through a bit of plastic that is mounted on a separate metal plate. Removing the plastic was a major PITA, the trick is to rotate it a bit and using a pliers and push it from inside out. After the plastic bit is loose, it’s possible to open it with a flat screwdriver. As you can see in the photo below, the plastic piece has deformed the cable so it looks like a U.

The power cable has been U-shaped by the plastic piece, and it's here the power cable is damaged.
The power cable has been U-shaped by the plastic piece, and it’s here the power cable is damaged.

I bought a new power cable with a Euro plug, the original cable is an old style ungrounded plug.

The old plug (bottom) was an old style ungrounded one, the new cable (upper) has a Euro plug. This is the reason why I bought a new cable and not just cut away the damaged part of the old one.
The old plug (bottom) was an old style ungrounded one, the new cable (upper) has a Euro plug. This is the reason why I bought a new cable and not just cut away the damaged part of the old one.

To start with, I cut away the bad part from the plastic piece.

The plastic piece is modified, it's the part that's cutaway that damages the cable.
The plastic piece is modified, it’s the part that’s cutaway that damages the cable.
The evil part is loose.
The evil part is loose.

The I tried to unsolder the old power cable. That was unsuccessful and the tubing on the brown hot cable was damaged, so I fixed it with some yellow heat shrink tubing. I then cut the old power cable and solder it to the new one. Before I soldered I did remember to run the new power cable through all the bits and pieces that the original cable went through.

I tried to desolder the hot cable (brown one) without success. I damaged the brown heat shrink tubing so I put on some new. The new cable was solder together with the old one.
I tried to desolder the hot cable (brown one) without success. I damaged the brown heat shrink tubing so I put on some new. The new cable was solder together with the old one.
I mounted the new cable exactly as the old one.
I mounted the new cable exactly as the old one.

I powered it up and it worked perfectly. By the way, putting the plastic piece back was an even harder task than to remove it, but with a lot of patience I succeeded. The S-330 is now back in the rack, but before I reassembled it I took some bonus photos of it’s inside. Notice all the custom Roland chips and the HxC SD Floppy Emulator as well as all the different outputs.

Repair photos

Bonus photos

Oberheim DPX-1 CPU problem?

In early March this year I bought an Oberheim DPX-1 on eBay. This example had the latest OS and the rare 8 output expander plus a brand new PSU! Unfortunately it was probably dropped on the ground on the journey from the US to Sweden. I was refunded but got to keep it since the buyer wasn’t interested in paying the shipping back to the US.

This night I opened the DPX up to try and find any clue of what was wrong. Not being an electronics expert, I tried usual of way of troubleshooting, namely removing part by part and see if anything made a difference.

The error could simply be described as the DPX not booting. When it’s powered on it immediately shows a strange character in the LCD display and then lits the MIDI CHANNEL, DATA DUMP and ERROR leds. See the video below day I shot when it arrived.

What I did tonight was:

  1. I started to remove the floppy cables and power cables. No difference, Same error.
  2. I removed the cable to the expansion board. No difference, same error.
  3. I removed the OS chips and doing that on a working unit would most probably generate an error. But no difference, same error.
  4. I removed the CPU, and without the CPU it’s certainly guaranteed that nothing should work, but no difference, same error.

However, removing the CPU, the most important part in a digital instrument, and not getting any other error points to the fact that the CPU might be the problem. I also remember that when I looked at DPX the last time when it arrived broken, the CPU had popped out. What I also noticed now was that one pin of the 64 pins were missing.

CPU is missing pin 1, also known as 'D4'. The CPU will certainly not run at all without this according to a forum member with lot's of 68k experience.
CPU is missing pin 1, also known as ‘D4’. The CPU will certainly not run at all without this according to a forum member with lot’s of 68k experience.

The CPU is a Motorola MC68000P10, a version of the in the 80’s widely used 68k family. I looked it up in the data sheet, and the pin is number pin number 1, named ‘D4’. I asked in the 99musik forum, and someone replied that the CPU most definitely can’t start without D4.

I took a look at some photos taken when the DPX arrived, and in those photos the pin is actually there. However, it could have been very loose then, just waiting to fall off. I’ve looked for the pin in the DPX, but I guess it’s like looking for a pin in a haystack.

I found a Chinese seller on eBay that sells  Motorola MC68000P10s for $8 including shipping to Sweden, I’ll order one of these within the next days and hope that it’ll bring the DPX-1 back to life again. To be continued…

Another Oberheim DPX-1 bought

I just bought another Oberheim DPX-1 from a guy in Stockholm since the one I bought in the US arrived in a non working condition. This also has the 8-output and cd-rom expansion. I thought those were rare…

Another bonus is the sticker from “Music Mania” which was a music store where I bought my first synth/rompler, the Korg NS5R in 1996. I still have that one, but I don’t like any of its  sounds anymore.

Oberheim DPX-1 arrived all dented

I just got the DPX-1 I ordered from eBay, unfortunately in a non working state. The front panel is dented, so someone has probably dropped it during transport. I contacted the seller who had just refurbished it and replaced the PSU. He wasn’t very happy to hear the news and offered me a refund.

If I want my $100 custom fees back I had to send it back. However, the transport to the US cost $150. So I decided to keep it and maybe try to repair it someday. Or use it for parts. Now I’ll have to find another one, they’re not too common.

By the way, I opened the DPX-1 and saw that the CPU was loose. Someone must have dropped it really hard. I put the CPU back in its socket, but the DPX-1 still wouldn’t start.