Hammond S6 Chord Organ Part 1: The dump

Took a Trooper (1990 Isuzu) load of crap to my local dump Saturday morning earlier than usual to try and beat the crowds. It’s not a real dump, it’s a transfer station with a few categories of stuff they take including electronics. I usually look around because the guy who runs it and drives the tractor always says “sure” if I want to bring something home.

I got to the spot where people drop off mixed-material stuff for processing – a nice way of saying getting crushed by the tractor so they can sort out the wood, metal etc for recycling. Alone in the middle of that spot on its side with a broken wood side and it’s power supply hanging by a wire was a Hammond S6 Chord organ – I knew exactly what it was – I have a buddy with one in his studio. I looked at the back and it had all it’s 1957 long black plate/ square getter RCA 12AX/12AU7’s, some sweet 6V6GT’s by GE, and some other nice tubes. My first thought was to just grab them but then I was struck by what nice condition the damn thing was in in spite of the harsh treatment of the last 30 minutes that had reduced it from perfectly preserved original to heap.

“Can I have this?” The guy laughs “If you want.” Then adds, “Can you fix that?”

“Sure.” I say.

“Guy just dropped it off – I was walking over here to get in the tractor to smash it.”

Timing is everything I think to myself.

He helps me load it up and I scout around grabbing all the chunks of wood I can and the bench.

As I drive the mile home I resolve to go to the dump as much as possible in the future, and to do my best to put the organ back together. I have been wanting an organ to mess with and play, and now I have one, free but for the repairs I need to do.

If I had been thinking I would have taken a picture at the dump, but I had other things on my mind just then.

Too bad I didn’t get a picture of my dad’s eye roll when I took this picture.
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Yamaha CS50 #1251 Part 2: closer, much closer

Calibrating and tuning a CS50 (and I assume the other nearest siblings) is an iterative process.  There are pitfalls at every step, and when you finally reach the end you get a nice easter egg -a tuned 4 (or more) voice synth!  In the last post I quickly diagnosed why my CS50 didn’t make a sound -having the TU (tuning) voltage jumped to ground.  This post is about other problems.  The CS50 circuitry has a lot of functions that are distributed among a couple of boards, so you may find you have a tuning problem originating in your SUB board, or a portamento problem originating from your PRA board.  Well, I had a TU problem coming from my SUB board – no matter what I tried, I got 6.5 volts at the TU terminal -trim pots had no effect… this terminal is supposed to be 4.000 volts.  Lots of head scratching and component replacement later I decided to just order a CS50 SUB board from synthparts.com -a handy side effect of CS50 voice boards being worth $400 – $500 each, making the CS50 worth about 2x it’s ‘complete working’ value in parts is that CS50 specific parts are CHEAP.  I got a complete front panel and lower chassis in like new condition for $150 while I was at it.  Too much money probably, but not bad really if you just want to fix your cheaply obtained synth that just happens to be worth more as parts.


Part way through a power supply recap.  I am told the small value green caps don’t really tend to fail, and to leave them alone.  After the recap it’s a good idea to look at the rail voltages again just in case. Continue reading

Polymoog 203A restoration parts list

For those mad enough to attempt a repair or god-forbid restoration of their PolyMoog, here is a running list of parts I have/will/need to replace.  This will be updated as I get stuff.


Power Supply has had its capacitors replaced.  Note the 4700uF is a radial -they were out of axial capacitors in the rating I needed.

P o w e r s u p p l y : : :  :    :     .

3x 470uF x 35V axial capacitors

2x 1000uF x 35V axial capacitors

1x 4700uF x 16V axial capacitor

3x LM723CN chips (not sure if these need replacing, but they are 33 years old and replacements are $0.65 each.)

Polymoog 203A joins the fleet and queue for repair

Few synthesizers have such a bi-polar reputation.  Amazing sounding and tedious to maintain, much less restore are the two poles of this equation.  Moog churned out a few of these – I am guessing a little over 4000 since this fellow is serial number 4021 and I’ve never found a reference to a later one.  Gary Numan famously used the Polymoog and so did a list of other luminaries if VSE is correct, but there isn’t anyone recent on that list.  I’m excited to fix this to see what it can do in a modern setting.IMG_6922

It just happens sometimes.  You mention you have an X you are looking to get rid of, and a friend says they have a Y they’d like to get rid of.  A little cash one way or the other sweetens the deal.  In such a way this complete, clean, low mileage, semi-functional Polymoog joined the menagerie.

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Yamaha CS50 #1251 Part 1: Bringing home strays

I decided to be ‘one of those guys’ and placed an ad on Craigslist looking for an ARP Odyssey (really want one!!), anyway -responses were thin and expensive except for a ‘broken Yamaha CS50’.  I went for a look and hey-ho next thing I knew I had a $600 CS50 in the back of my car.  Considering perfect ones sell for $1200 – $2000, the price was probably high for how little worked on it, but I decided to take a chance since I like a challenge.  It came with a lid and legs.


A good looking specimen.  All slider caps are present.  The keyboard is in great shape.  Not too many scratches.  Even came with the legs.  The LFO control board has a bunch of paint loss in the lower left corner -like the PO played with a metal band watch on.

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Moog Source #1253: there and back again and damaged in shipping

This is my Moog The Source.  It was a lovely all original piece in great working order.  In a fit of ‘I’ve got too much stuff’ a while back I sold this fellow on eBay and ended up having one of the worst selling experiences I’ve ever had.  I used this synth lightly in the studio and everything worked, even after several hours being on.  The buyer complained about lots of little things that frankly I suspect weren’t there, the aim of which was to get a partial refund.  After two weeks of having the money I got for this tied up in ‘item not received as described’ Paypal limbo I sent the buyer $50 and told them to ship it back.  They used about half the bubble wrap I sent it in and to round out the bad experience it showed up as you can see below.IMG_3019

Cheek took a pretty good hit.  Fortunately it still worked perfectly.  Shame about the original finish on the original wood… Continue reading

Roland EP11 Piano Plus wood cheeks

One of the downfalls of products from the early 80’s is the crap plastic they made a lot of stuff out of, and the putrid shades of slightly green beige it turns over time as the fire retardant bromine migrates out of it.  I bought this Piano Plus 11 off craigslist while I was restoring the Juno 60 to steal the key bed and maybe some buttons, sliders and other components out of.  I got it home, spent some time horsing around with it, and decided I just couldn’t kill such an interesting thing, so I just swapped its perfect key bed for the slightly glitchy one in the Juno 60.  What’s so interesting about it you ask?  Well, it has built in drum patterns, bass accompaniment and a kick-ass arpeggiator – all with a din sync out to drive other stuff.

This did 18 months of solitary confinement in my closet while my wife’s pregnancy progressed and then while the boy grew as I did late night/early morning diaper shifts.  One day I came across it while looking for some shoes and realized this would be a great first keyboard for a kid, so I pulled it out and sized it up.  The plastic cheeks -similar to a Juno 106 and JX-3P were offensive, so I decided to get some wood cheeks made.IMG_6711Here’s the nearly finished product.  The wood cheeks make the cream colored panel a lot more acceptable.  Yes, that’s a VP-330 under it, more on that later. Continue reading

Prophet 600 #5858 part 1: ‘how much will a $200 synth cost me?’

The danger with inexpensive synthesizer projects is it’s easy to justify spending money on them once they are in hand, and frequently end up being more expensive than if you just went out and spent eBay retail on the same board.  I can type the sentence, I can say the words, but when a $200 Prophet 600 was listed on Craigslist, you know I just had to make a play for it.  The seller responded to me by calling about 6 hours after I sent my ‘Is it still available’ email -which seems funny because I asked that question about 7 minutes after it was posted.  All the seller could tell me was that it didn’t power on and had some broken keys.  We met up the following morning and a deal was struck.  JD was a stand up guy for being true to his ‘first to come’ statement -even after receiving a lot of emails.


In the car.  I’ve seen worse.  I’ve started with worse.  My big fear was that the voice chips were missing, so I opened it up before buying.  All chips were in place, as were a lot of debris and mouse turds.

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Roland Juno 60 part 11: What ever happened to it?

I got a few questions about the final result of my efforts on the Juno 60.  Well?  I got it to basically function.  One voice had some issues that I couldn’t solve, but a trip to my friend Chris at This Old Synth got it to 100%.  I messed with it for a few months and decided that I didn’t need another big Poly sitting beside my Jupiter 6 and others so I sold it on eBay.


Here it/he/she is.  The wood sides came out amazing, the sound is/was fantastic, and some lucky guy paid me just under $900 via eBay for the chance to own it.

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Roland Juno 60 part 10: three years later… finishing touches

I didn’t mean to get side tracked, but life does that to you some times.  I just read through the nine posts I did about restoring this thing and realized I created one of those internet dead ends we all hate so much, where the guy is reaching from the top of the ladder to a woman who’s hanging out of the window of a burning building… well, not that dramatic, but I did leave the reader wondering what the hell happened.

The panel:  the panel that you see in post one, with all the paint and scratches and glue and stars… I replaced that with one I got from Doug at Synthparts that only had a few very small scratches and a tiny dent.

The circuit boards: All my parts eventually showed up after about 4 weeks and it went together.  I didn’t get any pictures of the soldering process, but who cares right?  One of the voices had some trouble so I eventually sent it to Chris at This old synth who sorted it out.  I still long for a good oscilloscope.

The keybed:  I never got the original keybed to work very well, always had some glitchy keys, so I bought a Roland Piano Plus 11 that used the same keybed -which happened to be in perfect condition.

The cost.  My original estimate ended up being low by probably $200, so I worked for free on this synth…


Everything in its right place.  I even put all the wire ties back where they went. Continue reading