Roland MC-505 Groovebox

This came in the mail today. Never had one before. It looks very cool and I really hope I get it working again because it’s sort of broken 🙂

Technical specifications:

• Polyphony – 64 Voices
• Oscillators – Acoustic Simulation and ROM Samples
• Filter – real-time resonant filter
• Drums – 26 kits
• Effects – 24 effects
• Arpeg/Seq – Has Arpeggiator and Sequencer (up to 95,000 notes)
• Keyboard – 16 small keys/buttons
• Control – MIDI
• Date Produced – 1998

This particular one was advertised as ‘broken / for parts’. It had been online for some time so I mailed the owner to see if I could find out what was wrong with it.

The owner replied: some buttons don’t work due to a crack in the PCB.

Right. As it was almost free I had it shipped to me and it arrived today. First thing I did was power it up to see what was working and what not.

Powered up just fine:

The previous owner said that the display works fine. Well, almost then 🙂

These machines are notorious for missing lines in the display and this one is missing 2 lines. Not really a problem and because all these things suffer from this problem there are a million how-to’s online on how to replace the display. This is a cheap repair so maybe I’ll replace the one in this device. Someday.

Pretty much everything works except for a bunch of buttons at the bottom. Especially the white and black ones you use to play something. Only the four on the right were working. I put it in test mode to find out what else was wrong with it. You have to press a special combination of buttons and then power it up. So I got it in test mode but you select the tests by pressing the SHIFT button and then one of the 16 buttons of which 12 don’t work :’)

So I got my screwdrivers and opened it up:

Well there’s your problem 😀

It’s not to bad actually. There are 2 traces that are disconnected due to this issue. So I got my super glue and soldering iron and got to work:

First I super glued the broken part back into place. Then I soldered 2 bypass wires onto the PCB, tested for continuity and everything seems to be okay!

Note to self: the soldering looks absolutely horrible. Fix it. And if my wife is reading this (:D highly unlikely): I need a proper soldering iron and it’s my birthday soon so there you go 😎

I put the back cover back on the MC-505 and switched it on.

Hmmm some switches that didn’t work before now work but there are still problems. It seems that switches 1, 3, 5, 7, 9 and 11 don’t work. 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 work fine. There is probably a problem between buttons 11 and 13 somewhere because 13 and 15 work but all the other odd numbers don’t.

Let’s have a look:

Another crack! The problem is the bottom lead close to the screw hole. The one above that looks a lot worse but it’s actually okay. I soldered another bypass wire to bridge this problem and closed it back up.

Now everything works except the #7 button. Almost there! 🙂 It’s late so I’m going to fix this last button this weekend. I put it through all the self tests and all the buttons / sliders / encoders seem to be working fine. What an easy fix this has been so far! 🙂

Beer time.

Update april 29th 2016:

The #7 button that didn’t work was right at the point where the piece had broken off the PCB. I had a look at it and I missed a trace that was on the other side of the PCB. So one more bypass was required to fix that. Below a picture of the last repair and a picture of all the repairs that were necessary:

I’ve tested it and everything works fine now! 🙂

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