[sdiy] How I spent my week (Polymoog restoration-long)

[Doug Terrebonne]

My first thought is all this work/money for a Polymoog??? I mean I've
got one that I finally got working with some power supply repairs but
damn, it's sure as hell not worth all the work you had to do! The
resonators are pretty cool but the rest is nothing that special, jeez!

Doug

--- Kevin Lightner <synthfool at synthfool.com> wrote:

> Thought I'd share something to illustrate an issue that kind of bugs
> me.
> 
> Maybe I've been in my hole too long or are just plain obsessive, but 
> when I hear of folks who say they're going to restore a synth, yet 
> have never seen what one should be like originally or have much 
> experience with the particular model, it can kinda irk me.
> For me, the term "restoration" is often used like the word "Mint" on
> Ebay.
> 
> Time and time again I hear of well meaning, but naive "techs" who say
> 
> they've restored a unit and didn't do anything close to what was 
> really needed for reliability, stability or to return to a stock, 
> original condition. Often they don't know what's missing, broken or 
> substituted because they've only seen a handful of the synths at
> best.
> They concentrate on replacing caps, but ignore old trimmers and 
> cracked soldering and other huge issues. Many "upgrade" their synths 
> with "much better opamps" or other mods, but don't do the base work 
> required to support improvements to begin with.
> Many believe that all of a synth's problems can be understood via the
> 
> schematics and don't take into account, the real world and what time 
> does to electronics.
> These situations, along with some bizarre assumption by sooo many 
> that when there's a problem, it MUST be an IC....  I offer what I've 
> done, so far, to a Polymoog over the past week. Very little of the 
> time has been spent on component level repairs, though there may be 
> more work necessary regarding this.
> Keep in mind- I've yet to open the schematics or power it up!
> There's no use testing a synth that has obvious visual problems and 
> can cause worse damage, imho.
> All CMOS IC's, previously in sockets (except 4046's) were tested on 
> an IC tester and several were bad and replaced. What's left, I will 
> soon discover.
> 
> This unit has been to four, count 'em, four LA techs.
> Each one took a stab at it and failed.
> Two said it couldn't be repaired, one said that he couldn't get parts
> 
> and one tried to convince the owner it was normal and "working fine 
> for a keyboard of its age."
> The owner even brought this tech an example of how it should sound 
> like, by letting the tech listen to some Gary Numan! :)
> Several of the dividers were replaced with a cmos based pcb (you've 
> probably seen this mod offered online before).
> Wires were strained, rust all around, dirt, bad soldering, loose 
> everywhere, substituted or missing screws, subbed components, klugey 
> repairs... on and on.
> A real mess.
> 
> 
> 
> The owner said he wants it as nice as possible and that costs are not
> 
> an issue, but time is. With that in mind..... ;-)
> 
> Jerry Casale/Devo Polymoog Keyboard, Serial #xxxx
> 
> 
> Back panel-
> All jack hardware replaced
> Jacks cleaned/polished
> S-trig jack replaced
> AC inlet replaced
> Resoldered fuse holder wiring
> Fused replaced
> Many screws replaced
> Tightened all fasteners
> Cleaned and detailed
> 
> Main structure-
> Epoxied stripped keyboard stand mounts
> Replaced missing screws
> Tightened all fasteners
> Cleaned and detailed
> 
> Front panel and PCBs-
> Resoldered boards
> Repainted silver lettering/legends, etc.
> Cleaned all sliders, switches and connectors
> Cleaned and resurfaced ribbon controller to new condition
> Rethreaded support mounts and replaced screws
> Replaced misc screws
> Tightened all fasteners
> Cleaned and detailed
> Board washed
> 
> Main divider board-
> Replaced (8) eight "mod boards" substituted for unavailable MM5823 
> divider IC's with original, new IC's from our stock. Board returned 
> to original.
> IC sockets eliminated
> Connectors cleaned
> All PCB connections resoldered and defluxed
> Board washed
> 
> Top octave generator boards (2)-
> IC sockets eliminated
> Connectors cleaned
> All PCB connections resoldered and defluxed
> Edge card fingers hand polished and cleaned
> Board washed
> 
> Power supply-
> Replaced all electrolytic caps with new, higher voltage types
> Replaced transformer connections with new, gold plated mating
> connectors
> Replaced 25 year old, single turn adjustment trimmers with new, 25 
> turn cermet trimmers
> IC sockets eliminated
> All PCB connections resoldered and defluxed
> Replaced poorly attempted transistor wiring with teflon coated, 
> silver plated copper wire and heatshrink (mil-spec/unmeltable)
> Resurfaced heat sink surface flat and applied new heatsink grease
> Board washed
> 
> Main voice card carrier boards (3)-
> All PCB connections resoldered and defluxed (2,626 connections!)
> IC sockets eliminated
> Main amp IC's replaced with new
> Connectors cleaned
> Edge card fingers detarnished
> Boards washed
> 
> Voice cards (71 voice boards, 3 driver boards, 1 bypass board)-
> All cards inspected and resoldered as needed
> Edge card fingers hand polished and cleaned
> IC sockets eliminated
> Electrolytic cap replaced on bypass board
> 
> Main PCB's (3)-
> IC sockets eliminated
> Electrolytic caps replaced
> Many trimmers replaced with multiturn cermet types
> Connectors cleaned
> Boards washed and defluxed
> Resoldered as needed
> IC sockets eliminated (except for uA726 ICs)
> Many IC's replaced- some were bad, some were substitutes
> 
> Keyboard-
> All bushings replaced (71)
> All keys cleaned
> 14 keys replaced (special weighted types)
> Spring tensions checked with gauge- 6 springs replaced
> New lube applied
> All screws replaced
> Key contacts cleaned and detarnished
> Connector wiring resoldered
> 
> 
> All solder used is Kester silver bearing solder
> 
> Unit will be tested, any component level troubleshooting completed 
> and calibrated next week.
> 
> Cost? I have no idea.
> What would YOU charge?? :)
> 
> 
> -- 
> Regards,
> Kevin Lightner
> 
> Myself: http://www.synthfool.com
> Service and sales: http://www.moogmusic.com/service.php
> Sales: http://www.cluboftheknobs.com