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

[Kevin Lightner]

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
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