One day, my trusty Blofeld started drifting out of tune – pretty unusual behaviour for a digital synth. Even if it was in tune first, the drifting started as soon as I touched the pitchbend wheel, so I suspected that this was the culprit.
Opening the Blofeld (all 18 screws on the bottom – remember?), removing the wheelbox, and measuring the pitchbend pot confirmed that the potentiometer was indeed damaged – while an end-to-end-measurement showed 9k, the end-to-mid-resistance could be virtually anywhere, screaming “Mechanical Damage!” to me.
The potentiometer is 10k lin with a knurled 6.3mm shaft and an M10x0.75 mount. Waldorf seems to have used a Piher T-21Y type (datasheet). As I did not find something fitting in my parts boxes, I took it apart, cleaned it, adjusted the pickup spring, applied a bit of contact grease, refitted the pot and closed the Blofeld
And now for the good part…
Although I measured that the wheel now zeroed around the pot’s 5kOhm mark, it had most definitely shifted slightly, so I started looking for the calibration routine. There has to be a calibration routine, right?
But the good Blofeld seems to calibrate on power-up and on the first usage of the wheel – no calibration routine for the wheels needed. Phew!
Important note: Be careful to ensure that the Molex connector for the wheelbox sits correctly – when I pulled the plug, the plastic holder for the pins got pulled towards the edge of the PCB so when I reattached the plug, it did not sit correctly. Rule of thumb: If the plastic of the connector is visible from the top, you might want to push it back under the PCB.
- A new glide pot for Jenny (Sunday, 27. November 2016; Schlagworte: contacts, Jen SX-1000, maintenance, Potentiometers, Synthesizer, vintage)
- V2.0: A Teensy-based MIDI Controller (Thursday, 14. September 2017; Schlagworte: Arduino, Launchpad Pro, Midi, MIDI Controller, MIDI Merge, OLED, OLED library, Pitch Bend, scale2x, Teensy)
- Fixing a Waldorf Blofeld’s jumpy encoders (Sunday, 24. January 2016; Schlagworte: auseinandernehmen, dismount, DIY, Drehknöpfe, fix encoders, Synthesizer, Waldorf Blofeld)