Hammond 102100 analog synthesizer tune up!

Bob Weigel of Sound Doctorin' ( Http://www.sounddoctorin.com ) runs through the tuneup procedures for the rare Hammond 102100 synthesizer. See also video doing sound demonstrations. These are a monophonic synth with a single vco and divide down square wave arrangement. Then footages are combined to create stepped saw waveforms which may be selected instead of squares from 32' to 4' and run through the VCF and VCA sections with modulations. But controls are limited to sliders for wind (noise) and tuning and volume, and preset buttons for 7 each waveforms, filter modes, sweep rates (repeating and one shot), Envelopes, and modulations. Still there are some very nice combinations and the sound is very warm though noisy base line so far. I may need to replace those electrolytics that measure a little high on esr meter.

Category:

Science & Technology

Tags:

• Hammond
• analog
• synthesizer
• demonstration
• troubleshooting
• tune
• up
• technical
• electronic
• repair

[joedaschmo117]

Hey bob, I work at a company where we buy and sell miscellaneous items on eBay, and we have recently purchased a hammond 102100. We plugged it in to an amp I brought in and all it did was hum when the keys were pressed, I watched this video over and over trying to figure out what the problem could be. If all else fails, we are planning on selling it for parts, but I think it may be due to a faulty tone generator. Then again, I'm no expert on vintage keyboards lol Would you have any idea? thanks

[sounddoctorin]

@joedaschmo117 go ahead and give me a call from the number on the sounddoctorin website and I can walk you through a few things if you want.

[eggman6]

What causes analogue synths to go out of tune?

[sounddoctorin]

Hmm well in the case of this one probably bad connections since it has a pretty stable oscillator. :-). But many synths use oscillator designs that employ chips or discrete semiconductors that are susceptable to temperature drift.  Polysix uses transistor pairs but they are pretty stable. Most other designs I've seen drift some. I have a mono/poly that has a chip that takes forever to warm up..but it's consistent. I should change it so I don't have to wait 20 minutes to use the thing!

[gummybits]

A few mistakes on the last comment, i was saying the en sx 1000 was a synth i was going to look at for inspiration for my own synth but the thing has like loads of envelopes.

[sounddoctorin]

Yeah I'd love to actually build an additive sometime that has some intermodulation options and stuff. I may do that using the crumar drawbar organ like I say on the trilogy scrap I have. But add some other harmonics in between to make it more interesting. It has 2 vco's already also so..tons of fun possibilities there. But individual envelope for each harmonic..an analog K5 would be so awesome :-) But it'd take a lot of space.

[pogsquatch]

I had one of these synths in the late 70's.

Cool sounds from Steve Miller's "Fly Like An Eagle"

were made on this board (with Echoplex).

[gummybits]

Ive not had mch xperience although i did make my own theremin, me and a friend who is studying electrical engineering are thinkingabout creating a basic mono synth 2 wave forms square and triangle fixed pulse width, mster filter and basic glide modulation, we estimate it would cost no more than £100, ive gota design the schematics this coming week tho, im loking at a few synths for inspiration, the jented than i thought, something along the lines of the yamaha cs 01 sx 1000 is more complica

[sounddoctorin]

I keep thinking about it but no time so far. I have some nifty ideas including weighted wheel controllers assignable to multiple parameters so you can fling it while you play and do a sweep with both hands free during the sweep. I've got so many parts here I'm thinking of doing it with some existing guts... might work over a Crumar Trilogy's.

[gummybits]

Have you ever made your own synth? im having thoughts on making a basic mono, with a few features, pretty budget, but analogue and hopefully tonally adaguate, by the way the elka sounds nice, absolutely no real time editing, but tonnally very nice, i got some pretty powerful strings out of it, watch this space!