Moog Polymoog Repair - Dead/Incorrect Sounding Keys - Synthchaser

[@markpeters284]

Great channel and I really enjoy watching your videos. Here is my Polymoog story if anyone is interested. I went into ABC music in Bristol in November 1991 just as they getting some used synths out on display which had come from their London store. One of which was a Polymoog 280a which had a label on it (Ex Gary Numan) sounds like they purchased (stole) a lot of Numans old kit which they spread around their stores. Me being a Numanoid since 1979 and already building up a collection of synths by this time i had to get this one. No surprise that when they turned it on a lot of the keys did not work and the lower filter bit did not function, but Vox Humana worked and we were soon playing Cars etc in the store. I left a while later with Polymoog under my arm (sort of, not really, it was a 2 man lift out to the car) and i was £300 lighter in the pocket. I did get most of the Polymoog keyboard working, fixed the lower filter with some new logic chips, replaced failed LEDs, rebuilt the power supply and worked out 2 of the divider chips were out. I paid quite a lot for 2 NOS original ones from an old road kit which came from EMIS in Bristol, but after i had fitted them in sockets they only worked for a short time before failing again. I learnt the lesson there to wear an earth strap as i probably fried them with static. Life then got in the way and all the synths have been in storage for a while now. When I finally retire it will keep me quiet for a good few years getting them all working again. Happy times.

[@hubbsllc]

Boy, this sure brings me back! A 203A (one of these) was the first synthesizer I ever bought, in I think 1985 or 1986. I was able to purchase a service manual and I caught my unit up on all the engineering changes that had been made. Over the years I had it, I repaired a failure in the power supply, a couple of dead LEDs, and at least one 4xxx chip. The keyboard contacts often needed cleaning and the one-per-key voice cards often failed to make good contact with their connectors - oftentimes a solid whack to the Polymoog's underside was sufficient to clear a dodgy key up temporarily. A 203A that works can be kind of dinky (especially the presets but the string preset is great) but it can also be a fearsome instrument if you start combining the VCF and parametric filter section output - even more so if you utilze the sections' separate outputs on the back panel and pan them differently. There's nothing else that can come close to that. One note on the video that I wanted to make is about what's being referred to as "shaping" to produce the sawtooth generation. What's actually going on is that a square wave is being *integrated* but the integration is being done on both the high and and low halves of the waveform and then one half is inverted and the two are summed - or something like that; I'm working from memory. But that's why the octave selections for the square generation are one octave lower from those of the sawtooth generation. The Polymoog really was the end of the line for divider-based electronic instruments; you couldn't take the technology farther than this in any practical way (some would argue that the Polymoog already took it farther than was practical).

[@0electricmotel0]

I have my fathers beloved polymoog keyboard in my basement awaiting restoration. Your video showed some of the same issues as my polymoog. The 200+ page service made the task look daunting but with a systematic approach ,as you’ve taken , it seems almost possible 😊

[@deadmanwalking6342]

Polymoog the organ back in the day that came back to the factory as fast it went out! PolyMoog a Dr Dave Luce creation of which Bob Moog called quote: A man who solved simple problems with the maximum amount of components!

[@MedusalObligation]

I had the opurtunity to buy either a New PolyMoog or New Chroma. I'm glad I chose the Rhodes! (I'm also glad I sold it 10 years ago.)

[@daveogarf]

Never realized that the Polymoogs were so problematic! Thank you so much, SynthChaser!

[@Baribrotzer]

That's one of the reasons they never caught on. Plus, you don't need 60 voices of polyphony - you only need about eight or ten even to play two-handed.

[@adamsteelproducer]

My dad was in music sales when this was only a couple of years old, no-one wanted them because they were always in for repairs…

[@scottlarson1548]

Michael Boddicker told Keyboard magazine in 1980 that he had to own *three* Polymoogs: one that's in the shop getting repaired, one that he's actually playing, and another that's he going to play as soon as that one breaks. He said that they failed often because he had to constantly move them. They don't like being moved.

[@hubaswift7640]

Sometimes, "they don't make them like they used to", and in this case I'm glad! That being said a machine that pushes ahead of it's time, and as such had some quirks and issues, is definitely still quite endearing. Great work on this Polymoog.

[@hubbsllc]

It's as if the microprocessor didn't exist.

[@PhoenixGuitars]

I appreciate your content and sharing your knowledge. Keep up the great work!

[@GEOSynths]

I love Videos like this...Thanks for doing it :)

[@SCOTTYD2031]

Thank you so much! Love your videos.

[@kennykeyboard]

I bought 2 from a guy in Oklahoma with about 30% functionality in 1991. Dirt cheap, as was most analog at the time. They both went downhill and the "fix it shop" in Mission Valley took them in and shortly after seeing a bench told me to take them back Not fixed/ no charge. I got one of them to play reasonably well for 8 more years before smoke emanated from the back and it screeched a terrible death to silence. Most of the components were actually good but just the typical shorts here and there which kept it from playing through a song reliably. Sold the parts of both to a store which specialized in used instruments. They gave me about half what I paid the other guy as store credit. Both businesses are now closed down. I currently have what I like to call my junior PS3300 (Korg Lambda). It works well enough. It's neither a Polymoog nor a PS3300 but still an example of that era.

[@barriewright2857]

Thank you very much for the education and information. Absolutely interesting and informative, didn't know these electronic keyboard's was so technical.

[@TheyreStillOutThere]

I see you're using Vishay axial caps, which is validating for me since I don't really know who to use in place of Nichicon for axial caps these days since they stopped making them and decided to settle on Vishay to see how it goes. I'm like, fundamentally opposed to using IC caps given how unreliable their stuff was throughout the 2000s-2010s. So for a consummate, highly skilled repair guy like you to be using Vishays counts as a sort of seal of approval in my book.

[@unclejerrysworld]

Very informative video!! You have an amazing talent and thank you for sharing.....

[@RubiconRecordings]

Really interesting video, I don’t have a poly moog , but I use to own a moog opus 3 , there is something about those old moogs, they sounds so big and warm

[@gilwe]

That's a beautiful beast!

[@hammondeggsmusic]

Even when it's sick, it still has that unmistakable polymoog sound...!

[@waheex]

super video, nice job

[@cyberjunkynl]

Would a temperature FLIR camera help in finding faulty components faster?

[@Synthchaser]

My FLIR branded thermal camera broke and the company wouldn't stand behind their product. A thermal camera may be useful, but I'd steer clear of the FLIR.

[@hubbsllc]

On a Polymoog? You betcha!

[@rekindle]

I love the Polymoogs , I found one and while it sounded amazing it had many problems so I had to pass ... can I ask though: if moog or behringer or someone wanted to make a poly moog clone today would it be easy to make? When the Moog One came out I wondered if it would be able to do the polymoog sounds but I didn’t hear any attempts at Vox Humana or the Strings preset so I’m not sure.... and finally, are there other divide down machines that also have two distinct divide down oscillators ?

[@hubbsllc]

Maybe the ARP String Ensemble did? I don't know. Yes, especially with surface-mount devices a Polymoog clone would absolutely be possible today, and in a much more compact form factor. Some 1970s digital and analog ICs might not be possible to source today; I remember there was an op amp that I replaced in mine that wasn't trivial to source. I think I had to use one with a can-style case instead of a DIP.

[@rekindle]

thanks for your reply@@hubbsllc ! I wonder why no one wants to make a clone, the Poly Moog I got to try had a really epic sort of "stage" to it, a variation on Moog sounding bass while still being really unique. I thought Dreadbox might be going for something similar with their Abyss synth...anyway, I'm glad you got your one working!

[@Babysqid]

Sadly my budget never quite reached the 203a level but I did have a 280a for a while and yes, getting all those polycom cards to sound *exactly* the same did feel like modern-day haruspicy

[@marcbrasse747]

Very interesting indeed!

[@daccrowell4776]

Yeeee gods... y'know, this is probably the only synth that's more terrifying inside than the CS80. And I have a CS80, so I'm speaking from experience. I used one of these ONCE and ONLY once in 1980. I found it to be a real PITA; I couldn't get anything I liked out of the instrument. And much of that seemed like it came from the confluence of two different and somewhat incompatible technologies: the Moog parts, and the Cordovox parts. Cordovox, btw, is a company out of Italy (back then) which Moog worked with in the 1970s. And Cordovox made...hold down that snare key...divide-down combo organs, ensemble keyboards, etc. AND...one of those organs affectionately known as the White Elephant was equipped with a Moog Satellite solo preset keyboard. So, yeah... there's a rather substantial connection there. Now, if you go back to the mid-70s, Moog had a prototype polysynth that wasn't a divide-down...this was the mysterious Moog Constellation, which can be clearly heard on ELP's track "Benny the Bouncer". But what's not clearly known is that Bob had to send Dave Luce WITH the Constellation during the "Brain Salad Surgery" sessions for the sole purpose of keeping the damn thing operational on an hour-to-hour basis! Given the general shortage of Dave Luces at Moog back then, Moog had to do SOMETHING...so it's suspected that Moog used their relationship with Cordovox to graft a variation of divide-down architecture onto the rest of the Constellation's signal chain. Why? Because ELP'S "Brain Salad Surgery" blew the hell UP! And suddenly there were people buzzing about this mysterious Moog on there. And Moog was in one of its more desperate monetary struggles in the years following the move to Buffalo. So they went for a quick, cheap fix...which was neither, in the end. Moog doesn't have the best track record for polysynths. After this...and its crippleware counterpart, the Polymoog Keyboard...they gave the world the Memorymoog. You don't see many working, stock Memorymoogs, either. In its case, the computer-controlled bits would eventually go spooey, with the big clue there being a complete failure of the VCO tuning system. Oh...and if you wanted MIDI, you had to have that retrofitted except in the late runs; around the same time, Sequential was killing it with their first MIDI synth, the Prophet 600, and Roland then dropped their first MIDI keyboard, the Jupiter-6. You can actually expect these to work...whereas the Memorymoog was something you didn't dare SNEEZE near! And with the drop of Yamaha's DX-synths...that, as they say, was that. Tbh, I actually thought for a brief second when I saw the words "Polymoog Repair" that I was about to be treated to a YTP-style fiasco involving 500 lbs of gravel, thermite, tannerite, and cheap firecrackers + Polymoog. Instead, it was an actual repair video with no fire, explosions, smoke, melted plastic, etc. A tad disappointing...until the horror of the actual construction was revealed! If synthesizers were in freak shows, the Polymoog would have to be the two-headed, eight-legged dog. Just one thin dime, ten cents, one more tenth of a dollar, and you can watch it feed on its native diet of capacitors, money, and buyer remorse! Hurry, hurry, hurry...! 😂

[@hubbsllc]

OK - I thought the Moog Apollo (the polyphonic instrument within the Constellation rig that Emerson played which was minus the Taurus) worked the same way a Polymoog did - divider technology.

[@moogman5]

The wide plastic multi cable connector on the top, center of the power supply board is also a weak point...I had to cut that connector out and solder the wires directly to the board when I had one of these years ago

[@Synthchaser]

Yes! A few months ago I had to replace a problematic one for a customer. That's one of the few connectors that's a standard pitch so it can be replaced with a 0.156" molex header and housing with good results.

[@blenderbuch]

Is that middle panel with the LED-7 seqment 3d-printed?

[@AlanLong-h5s]

I had a polymoog keyboard and suffered the same issue, unfortunately it seemed to be self inflicted as I found out that the leg fitting screws underneath were made too long and if you tighten them without the leg attached they short out the board above.

[@tommyboy9998]

Ahh, the polymoog - the steamboat of synths.

[@douro20]

I could imagine how hard it would be to service a McLeyvier, let alone one of these. The McLeyvier is also analog, and it could have up to 128 voices!

[@ScottFromCanada]

I may be wrong (I hope not for a change!) but I think you pointed at the wrong spot for the high frequency oscillators. They are on the top left board. You pointed at the Top Octave generators.

[@Synthchaser]

The service manual calls them the High Frequency Oscillators and calls the oscillators on the top left board the "Reference Oscillators". It's an unnecessarily complicated design.

[@ScottFromCanada]

@@Synthchaser Ahhh so it does. I haven't worked on another synth with top octave/divide down stuff (are there any??) so I'm not sure if it was really necessary but I'm pretty sure it was so they could do the pitch modulation for each oscillator individually and maybe for pitch stability. Although you never know what's going to be broken when you turn it on, it's always perfectly in tune!

[@straighttalk2069]

Very interesting and funny (if you look at the synth in a funny way) video.

[@kirkanos771]

@6:13 is this the LockpickingLawyer channel ? :D

[@thaiexodus2916]

Quick, cheap effective fix for crappy circuit board contacts. Obtain some fine grade silver oxide power and super thin cyanoacrylic lacquer - super glue premium grade. Mix the oxide with the glue into a paste and apply to the very very clean contacts. Make some test pastes. allow to cure and check resistance with an ohm meter and blunt probe. Rough up the coated contact slightly with 400-600 grit sandpaper. A one ounce bottle, roughly 25 grams of Ag2 O is good for several thousand contacts. I store up cards and bad contact components then make a run of several hundred coatings. In the case of your Moog, you can 'plate' all your boards contacts in a half hour or less. It only takes a few molecules of silver oxide to make a good electrical conductor and several million should be exposed in the paste.

[@Ojref1]

Looking at those keys makes me wonder if Mr. Reznor laid hands upon it. Heh.

[@iansampson2492]

I remember looking at one in the late 70s in Boston....if memory serves it was 3500.00 at time new...

[@HOLLASOUNDS]

Complex looking machine.

[@matthiaswilhelm9813]

Thanks,a good oldy repair.I have Displays changed on GEM Wk8 and old E-mu Flashs rebootet with good Floppy disc drives and the good disc.🤐🙄😂😂😂

[@deantiquisetnovis]

I bought a broken Polymoog for cheap back in the 1980s. I think I paid 500 Deutschmarks for it. The problem was one broken UA741 which created some high frequency modulation on the power rails. That brought the whole synth down. And yes, I can confirm that moving that beast around or even temperature changes in the room cause all sorts of problems. Plus, that monster is super heavy and the sounds - which of course can’t be saved, are very basic. Such an overrated machine!

[@hubbsllc]

I disagree re overrated if only because it can get into territory no other instrument can touch. And I disagree re basic. I discovered that if you mixed together the VCF and parametric filter sections and gave the VCF envelope a slow downward sweep, the combination sounded like no other synthesizer and that if you went one step further and brought the separate section outputs on the back panel to their own mixer channels and panned and especially effected them separately, the result is absolutely hair-raising.

[@deantiquisetnovis]

@@hubbsllc and now try to save your fantastic sound creation ;-)

[@2009numan]

I know that synth from the Vox Humana sound famously used by Gary Numan

[@hubbsllc]

The Polymoog Keyboard (model 280A) had the Vox Humana preset but the Polymoog Synthesizer (model 203A) did not. However, if you had the schematic for the 280A's preset cards I don't think there would be any reason why one couldn't replicate a Vox Humana preset card and put it in place of one of a 203A's preset cards. The preset cards contained jumpers and resistor arrays to take over the button and slider settings from the front panel and also included an aesthetically-voiced fixed filter. It's that last aspect of the preset cards that keeps someone from being able to just set the controls of a 203A a certain way to reproduce the Vox Humana preset.

[@curmudgeonextraordinaire1884]

Looks like a nightmare to work on!

[@TheDavidPoole]

That's what the inside of a synthesizer SHOULD look like!

[@TheyreStillOutThere]

I have a foot pedal for one of these bad boys!

[@synthebo]

😮😮😮🤩🤩🤩🤩🤩🤩👏👏👏👏👏

[@notsewmad]

Great info but someone does not know the difference between an electrolytic capacitor and a tantalum capacitor

[@Synthchaser]

The solution for you then is to watch more of my videos and you can learn about these things!

[@marcse7en]

Strange pronunciation of Polymoog? ... "Poly-moag" Surely it's pronounced, "Poly-moo-g" ... As in a cow's "moo" Is it a US thing, like "solder" being pronounced, "sodder" ?

[@Synthchaser]

The company was created by a guy named Bob Moog. "Moag" is how he and his family pronounce their name, so I respect it.

[@hubbsllc]

Rhymes with "rogue."