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Post by brassteacher on Feb 22, 2011 22:45:17 GMT
Just keeping up to date. I had a very kind donation of the insides of the polycom IC and am in the position to make, er well one to start with. Of course I have the original PM to try it in so should be a synch! (Optimism is very useful). I understand what has been said with regards making things to keep them going in as near to the original as possible - like making a polycom card - and maybe there is mileage in that as it's a simple job to replace one; compared to taking everything out and starting from scratch. The thing that bugs me the most is all those connectors.. mechanical things are usually the first to fail. Once the polycom is out of the way as a hurdle the rest should be easy enough. Everything is more or less still available or at least there is something available that will do the job in the same way. As to mounting surface mount parts we have an automatic pick and place machine so that's not a problem. I rather like the idea of putting a re-vamped one next to an original to see if anyone can tell the difference without knowing which is which! (Might be a good excuse for a world challenge) That's cool! I'd love to know what's inside, at least as far as circuits go, i.e., how many waveshapers, filters, VCAs, EGs, etc.. It would be interesting to see how these were implemented also. ICs are usually 10 times more complex, or 10 times more simple on the inside than a lot of people realize. For instance, it is possible to make a hex buffer chip with as few as 6 transistors total, and a quad 2-input AND gate chip with as few as 8 transistors total. Another thing I'd love to know is how did the Moog factory go about calibrating a Polycom card. I've also learned recently that the LM13600 is still being made as an SMT chip (NJM13600), and they are CHEAP. That's as good (and identical except for pinout) as having two CA3080s on a chip, and two buffers to boot! Just two of those chips, with an SMT 556 chip, and you could build a complete monosynth in a space the size of a Polycom card, incuding an LFO even, for less than $6 in parts.
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Post by spoonz on Feb 26, 2011 10:45:07 GMT
Just keeping up to date. I had a very kind donation of the insides of the polycom IC and am in the position to make, er well one to start with. Of course I have the original PM to try it in so should be a synch! (Optimism is very useful). I understand what has been said with regards making things to keep them going in as near to the original as possible - like making a polycom card - and maybe there is mileage in that as it's a simple job to replace one; compared to taking everything out and starting from scratch. The thing that bugs me the most is all those connectors.. mechanical things are usually the first to fail. Once the polycom is out of the way as a hurdle the rest should be easy enough. Everything is more or less still available or at least there is something available that will do the job in the same way. As to mounting surface mount parts we have an automatic pick and place machine so that's not a problem. I rather like the idea of putting a re-vamped one next to an original to see if anyone can tell the difference without knowing which is which! (Might be a good excuse for a world challenge) That's cool! I'd love to know what's inside, at least as far as circuits go, i.e., how many waveshapers, filters, VCAs, EGs, etc.. It would be interesting to see how these were implemented also. ICs are usually 10 times more complex, or 10 times more simple on the inside than a lot of people realize. For instance, it is possible to make a hex buffer chip with as few as 6 transistors total, and a quad 2-input AND gate chip with as few as 8 transistors total. Another thing I'd love to know is how did the Moog factory go about calibrating a Polycom card. I've also learned recently that the LM13600 is still being made as an SMT chip (NJM13600), and they are CHEAP. That's as good (and identical except for pinout) as having two CA3080s on a chip, and two buffers to boot! Just two of those chips, with an SMT 556 chip, and you could build a complete monosynth in a space the size of a Polycom card, incuding an LFO even, for less than $6 in parts. The Polycom contains a filter, EG, two VCAs, and some waveform processing (variable pulse width generation) i beleive the original design brief wanted some other modulation features in the chip but the costs meant it was bordering on overpriced as it was and adding Voice mod to 71 already expensive to produce Ic's was ruled out. Re the calibration of the card, Kevin Lightner has all of the factory docs for production and testing. He sent me soem scans of a few and i'm sure he will have the card production/testing specs. He's very approachable and helpful so drop him an email.
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Post by brassteacher on Feb 27, 2011 1:04:26 GMT
The Polycom contains a filter, EG, two VCAs, and some waveform processing (variable pulse width generation) I was aware of this, I was looking for specifics as well as verification. I've learned over the years that sometimes the actual circuit in hand may differ greatly from documentation/schematics/service manuals.
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Post by spoonz on Feb 28, 2011 10:13:21 GMT
The Polycom contains a filter, EG, two VCAs, and some waveform processing (variable pulse width generation) I was aware of this, I was looking for specifics as well as verification. I've learned over the years that sometimes the actual circuit in hand may differ greatly from documentation/schematics/service manuals. The patent for the custom parts of the Poly tells it in more detail which is online with a bit of searching. (with some circuit diagrams). The summary of the Ic is it is 25 transistor, It takes two sawtooth inputs and performs clipping modulation on one and pulse-width modulation on the other, pans between them, handles the envelopes, and implements a two-pole ladder filter. The patent number is 4099439
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Post by brassteacher on Mar 4, 2011 22:55:01 GMT
I was aware of this, I was looking for specifics as well as verification. I've learned over the years that sometimes the actual circuit in hand may differ greatly from documentation/schematics/service manuals. The patent for the custom parts of the Poly tells it in more detail which is online with a bit of searching. (with some circuit diagrams). The summary of the Ic is it is 25 transistor, It takes two sawtooth inputs and performs clipping modulation on one and pulse-width modulation on the other, pans between them, handles the envelopes, and implements a two-pole ladder filter. The patent number is 4099439 Now THIS is very useful info, thanks! It never occurred to me to search patent files, I forgot they invented that silly chip! Back after I'm through reading!
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Post by Polymoog Lover on May 10, 2011 18:28:23 GMT
Wow, it's great to see that this thread is still alive! I hope it has helped as many people as possible!
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Post by pulseczar42 on Nov 27, 2011 4:27:37 GMT
Fingers crossed this thread's still active, I'm hoping for a little reinforcement from someone with PM repair experience. My aunt gave me her old 203A, serial #3729. She bought it new in the 70s, never took it on tour or anything, so I'm reasonably hopeful that its problems are not too serious. There's no sound from it. Following the service manual's PSU troubleshooting procedure leads me to the right HFO board (#2): if it's disconnected, all supply levels are good, but if it's connected I lose +15V. None of the other boards being disconnected has an effect on the supply levels. Nothing looks burny on the HFO board...I've got a DC power source so I'm thinking I'll try powering it by itself and see if I can't figure out which of the ICs/BJTs is sinking the supply. The manual suggests that if an HFO is dead then the BJT "Q1," IC1 (DM7413N) or IC4 (DM7426N) is to blame. Fuck me if either of those ICs doesn't exist anymore, I'd really like to get this baby working. If I got some sound, I could see myself going the distance and really putting in some time restoring it to full glory. Any thoughts/advice? If anyone could reassure me I've sussed the problem correctly that would be helpful, or if anyone knows I'm drawing the wrong conclusion that would be helpful as well. Thanks!
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Post by martymoog on Nov 27, 2011 19:22:12 GMT
Hi Pulse, on the evidence given it certainly looks like you've isolated the problem, those components can be sourced if you hunt around so it shouldn't be too hard to get her going again Marty
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Post by pulseczar42 on Nov 28, 2011 0:45:45 GMT
Thanks Marty! Nice to know people are still fiddling with these things.
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Post by Polymoog Lover on Nov 29, 2011 18:09:51 GMT
wow..... this thread is still alive? I'm surprised. Usually all of my threads on all forums end up fading.
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Post by martymoog on Dec 2, 2011 20:35:12 GMT
If Carlsberg did Polymoog threads ...
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Post by martymoog on Nov 3, 2012 23:20:35 GMT
Still a useful thread !
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Post by Dubsounds on Nov 7, 2012 17:29:39 GMT
Agreed Marty, I'll put it on a sticky so you won't have to bump it ;D
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Post by martymoog on Nov 10, 2012 15:48:00 GMT
;D
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Post by synthrodriguez on Jan 21, 2018 15:32:02 GMT
HA HA! FIRST POST, LONG, AND A NECROTHREAD REVIVAL!! THE WORST POSSIBLE COMBINATION!!
I found this Polymoog post and it appears there are a lot of enthusiasts here. I'd like some feedback please regarding upcoming Polymoog restorations I'm about to tackle, my first work on Polymoogs.
I have a client that gave me three synths, s/n 1112, s/n 3087, and Prototype No. 5. Moog apparently made 6 prototypes before the synth went to production so I've got No. 5 here as part of the set. The controls on the prototype are different from the production model, but it "looks" like a production unit, i.e., quality graphics, same basic layout, etc. At a glance, you probably wouldn't notice it's not a production model. Some of the control parameters are different from the production units (some missing, others added). Also, the keybed starts on C instead of E.
The client told me if I could get one synth working 100% I could have the other two. There are a few cards missing from the individual units but from a quick inventory, it appears there's enough here to get two synths working (bad chips during the process notwithstanding).
Due to condition, s/n 3087 is easily the unit to go back to the customer. That leaves me with s/n 1112 and the prototype. Which should I restore?
The production unit has lived a hard life; the panel is stained dark with cigarette smoke, lots of battle scars, keys with burn marks, worn panel button graphics, something I wouldn't normally have in the studio, but it's not too far gone to make it playable again. It will certainly clean up some but it's never going to be a "nice" example. The prototype is in reasonable condition, but I have no way of knowing how it's supposed to work, what with the odd control set, no schematics, etc., so there's a dark rabbit hole time-sucker of information dearth, schematic work, and general head-scratching.
I feel like the prototype might only be valuable as a novelty and the production unit would have more intrinsic useful (and monetary) value. If I restored the production unit however, I would end up with a sad basket of Polymoog prototype parts that deserves to live on in some Moog maniac's lair. So restoring the prototype might be a cool thing, but then who would want a Polymoog that in the end, really isn't a real Polymoog?
I would appreciate some thoughts on what path you might take. Thinking about it, I guess I could spend the time and money to get them both working, but I really didn't want to do that. Both seem like a viable options to restore, but a prototype might only appeal to the very smallest cross-section of Moog types when it would come time to sell (whenever that may be). Thoughts appreciated.
Thanks -
Scott in Ohio
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Post by Dubsounds on Jan 22, 2018 11:47:49 GMT
Hi Scott and welcome.
The prototype is more valuable to a Poly nut than anything.
How about fixing up 3087, (sourcing 1112 for parts and getting to keep the other two). Then, sell the Prototype to a collector as is, (a collector will insist on it being original so don't do anything to it) and break what's left of 1112 for parts and sell those individually?
I can't think of anyone wanting a cigarette burned donor Poly and you would get far more than its worth offering the parts to other restorers like Jared.
That way you spend nothing, AND make some money and don't have an oversized coffee table which would take months of work and cost all your profit and more to get a squeak out if it.
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Post by synthrodriguez on Jan 26, 2018 21:46:42 GMT
Oooo I can't part it out. Not in my nature. It deserves to live, dammit!
Hmmm, have to mull it over.
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