More Synth Work Chronicles

This weekend I’ll be doing minor repairs to the Roland JX-3P and Realistic/Moog MG-1 synthesizers, as well as some modifications to the Marantz PMD-221 cassette deck and Intellijel Eurorack 2HP passive Mult module.

Roland JX-3P

  1. Record example sound with chorus off, chorus on. Check volume pot and output level switch. DONE
  2. Replace volume pot, output level switch as necessary. VOL POT DONE, OUTPUT LVL SWITCH OK
  3. Replace MN3009 BBD x2 DONE
  4. Close up and test. Re-record example sound with chorus off, chorus on. DONE. FAIL. NEW ARTICLE WILL BE POSTED SHORTLY.

Realistic Moog MG-1

  1. Record example playing of all keys – explore defective notes. Explore delay from poly to mono osc.
  2. Replace octave divider(s) as necessary.  BUILT TWO OCTAVE DIVIDER REPLACEMENT BOARDS USING BOB GRIEB’S PCBs
  3. Confirm defective notes are repaired.
  4. Replace CV extraction capacitor per Bob Grieb’s recommended keyboard delay mod.
  5. Test keyboard delay.

Marantz PMD-221 Pitch Control Mod

  1. Test deck in delay loop. DONE
  2. Install “pitch control while recording” mod DONE

Modify Intellijel 2hp passive Mult module

Intellijel Mult Front PanelI used some quick ‘n dirty tactics to turn this simple Eurorack Mult into a Dual V-Trigger to S-trigger Converter.

I took some pictures while I worked. It will get its own article later this weekend.

Tested. An S-trigger is generated when the voltage goes above approximately +0.55V. All things said, this was a very worthwhile mini-project. New article with details will follow shortly.


Coming up…

Next priority jobs:

    • Sequential Multi-Trak – Tauntek Update IN PROGRESS

(This job would have been my top priority this weekend, but Mouser decided to not ship my Schottky diodes for no good reason)

  • Korg EX-800 Sale Preparations: Moog Slayer / FM / Side Panels
  • Yamaha CS-40M Repairs
  • Display Replacement: KorgWavestation A/D (and maybe get some rack ears)
  • Display Replacement: Yamaha TG77

Stay tuned!

I will post further updates. Use the tags if you are trying to follow something specific.

3 thoughts on “More Synth Work Chronicles

  1. Hi!

    Would you mind explaining the PMD 221 mod that enables speed control while recording?

    Best regards from Sweden

    • It appears I made a mistake on the original post. I acquired 2x PMD-221 and 2x PMD-430 (I think) from an auction. I performed the mod on the 430 – the stereo version.

      I will be posting a further update about this, detailing the mod and how it works. Also I still plan to mod the PMD-221.

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