rhythm unit extraction

[dylar]

This isn't exactly stompbox related, but this forum has been so helpful in the past I thought I'd ask. 
I have the opportunity to tear apart three old organs, one of which is a Yamaha Electone BK5 (havent seen the others yet).
I want to save the rhythm units to use as an independent drum synth.  Does anyone know anything about this? Is it as simple as identifying the boards, extracting them, powering them and hooking them to an amp?  Or will it be impossible?

[petemoore]

I want to save the rhythm units to use as an independent drum synth.  Does anyone know anything about this?
  Drum synth conjures image of 'playing' the drums. Not sure what 'rythm unit' has for interface or electronics...I get the idea there are algorythms which trigger tone generators like in 'console organ rythm section'.
Is it as simple as identifying the boards, extracting them, powering them and hooking them to an amp? 
  Electronics...simple ? "Simple had everything else except the power supply perfect [forgot to plug it in].
  Which brings to working with HV-AC, which necessarily complicates safety.
  Quote: "seemed simple at first"...
  Or will it be impossible?
  'It' is usually possible, but she grades every detail, and there are always details which show up later, this invariably equates to "know more: after".
   She has a way of pointing out every detail at all times, doesn't take messages so can't be called upon to break anything down to something as simple as one particular detail.
  And this project sounds like it has a number of them, miss one and it can become brutally evident she does not grade on a curve, only 100% obedience to her law is recognized as correct and rewarded with 'works as intended'.
   That said...
  What are the PS requirements of the rythm unit ?
   Does the rythm unit function or interface have requirements in addition to signal out/routing and power supply ?
  Is there a signal or trigger input...gotta be...details details !
  What is the output impedance...can almost certainly be worked with.   

[dcjim]

I've got a similar task at hand as it goes. I want to extract the filter section from a Korg PE1000 Polyphonic Ensemble keyboard.

I looked at the schematic

I looked inside the beast

I looked at the schematic again

I carried on looking inside the organ, I found a dead spider, a lot of hair and dust and felt a bit creeped out

I looked at the schematic

I sat and stared at it all for a bit

I packed it all up and went to bed

That was about a year ago

Seriously though ... the problems I encountered were that the schematic didn't identify the board layout and following various signal cables by sight it seemed likely to me that the functionality was spread over more than one board

That said, James Walker (a well known synth repair guy) has told me he could do it, so it is possible

Get the service manual hopefully with schematic and board layouts and hope for the best. If you're lucky the drums will be on a single board and there'll be pads for audio out and power in or things to that effect

[frequencycentral]

I've got a similar task at hand as it goes. I want to extract the filter section from a Korg PE1000 Polyphonic Ensemble keyboard.

While I approve of ripping apart old organs for parts (done it myself), the Korg PE1000 Polyphonic Ensemble is a cheesy classic, and in a different league. You should mail it to me, I'd love and cherish it. I'd even build you a filter.

[Mark Hammer]

The PE1000 is definitely something that should be restored to working order, rather than cannibalized.  At the same time, the rhythm section is of no earthly use to that thing, and appears to be mounted on a separable circuit board.  That chassi real estate could be more profitably applied to further processing of the keyboard in some fashion, given that it has a discernible trigger/gate of some sort.

As for the Yamaha Electone BK5, I am less optimistic.  A lot of those "rhythm sections" are VERY simple devices, that use damped oscillators like that shown here: http://www.paia.com/ProdArticles/syndrum.htm

You could actually build yourself a bunch of these probably faster than you could take the organ apart and figure out what goes where.  Schematics and board layouts for that category of drum voice generator are in abundance on-line.  Here is a 7-voice schematic: http://www.paia.com/prodimages/drumtone.gif

[pinkjimiphoton]

if it's a solid state unit, yah, you can remove it, but you probably won't want to...they are pretty lazy and lame as drum machines go. simplest way is to trace from the control switches for the rhythm unit itself, that will lead you to the board.
don't worry about the voltages hurting ya if it doesn't have tubes.
when ya find the board (s) remove them, label which wires went to what, and you shouldn't have much of a problem from there getting it powered up and using it.
they're usually pretty simple circuits, tho they may take up a lot of real estate. some are just chips, but most are on one or two boards inside the chassis of the organ somewhere.

i LOVE cannibalizing organs, been doing it for years. you can make some nice small tube amps with minimal modifications, and some of the 60's era ones are bloody LOADED with cool, useable parts.

best of luck, mate!

[Hides-His-Eyes]

If you want an easy drum machine, take the noisy half of the Boss DR-55 and use a bunch of 7555/decade counters for your beatz. Or diodes and toggle switches if you're feeling quite brave.

[dcjim]

Wow!

I'm surprised by all the PE1000 love. To be fair the guy who said he could remove the filter for me was a bit horrified at the idea. A friend gave it to me and then a while later wondered if it was worth anything and asked for £50. I was using it for some recording at the time so I felt like I didn't have a choice. It is very poorly by the way. I figured a restoration would be a few hundred pounds and at the time they were certainly worth less than that. Are they valuable now?

What is their historical significance? Weren't they one of the first fully polyphonic boards or something?

Hey I'm glad there are synth heads here too! Guitar pedals and synths. Double fun!

[Mark Hammer]

Strings, keys, pads, doesn't matter.  What matters is that they make cool sounds, and often that they do so in unpredictable manners.

[petemoore]

  Aged Analog Cheese is good stuff.

[thedefog]

instead of ripping that drum machine out, I'd just sample each of the sounds and throw it into Fruityloops or something. Sounds like too much work to rip it out of there.

Besides, you can get stand-alone drum machines pretty cheap on eBay. I bought a sound master Rhythm-1 for $40, made a simple buffer for Piezos disks to trigger the individual sounds on it, and added jacks to plug the piezos into on the side for probably less than $20 and now I have a triggerable/playable analog drum machine that I can also run my CV triggers into. Fun stuff! Still need to use it on a song though.