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

[Kevin Lightner]

>
>What IC tester are you using there?

It's a small device with a ZIF socket.
Got it from JDR Electronics years ago, but they no longer carry it.
Checks 4000 and 4500 cmos, 74XXX TTL and some dynamic rams like 4164, etc.
Machine has paid for itself many times over.

Check these out: http://www.sunequipco.com/comp/ICTESTER/INDEX.HTM
The 17002 model can test several types of opamps, which would save a 
lot of time and waste here.
The tester I have now is equivalent to the 17001 basically.

Also, I use a Vu-Data 5110 for testing transistors and matching. Out 
of production, but a very cool box.
I told Phil Cirocco about mine and he bought one too :)
You can find them on Ebay from time to time. This one was recently 
calibrated and saves a LOT of time also.


>
>>  Several of the dividers were replaced with a cmos based pcb (you've
>>  probably seen this mod offered online before).
>
>Nope.  Got a URL handy?

Actually I don't, but either synthrestore.uk or one of those.
Someone on this list must know. :)

>
>  > S-trig jack replaced
>
>It having been a LONG time since I've seen one of those (and I don't have the
>service data handy at present),  is that the same connector that Moog used on
>other stuff?  What do you call those,  anyhow?

Cinch Jones

>
>>  Repainted silver lettering/legends, etc.
>
>That's definitely further than I'd go.

Not that hard really.
I keep a lot of different paints around anyways.


>
>>  Cleaned all sliders, switches and connectors
>>  Cleaned and resurfaced ribbon controller to new condition
>
>I always did like that ribbon controller.  How did you fix that?

Discarded the surface tape, cleaned the contact strip and element and 
applied new tape.
I have some of the original tape they used on these smaller ribbons. :)

>
><...>
>
>>  Board washed
>
>In what?

Soft water. Simple Green detergent.
Sounds crazy, but it's proven fine here.

>
><...>
>
>>  IC sockets eliminated
>
>I notice you mention this a lot -- why do that?  Have the sockets in those
>proven to be that unreliable?  Sure sounds like a lot of work.

Yeah. Moog used inline strips on these.
The two rows aren't hooked to each other.
After a parade of techs, the pins fatigue and the compression of the 
socket contacts isn't as tight.
Sometimes they're plainly loose, others fail when they actually see current.
By eliminating the IC sockets, I eliminate hundreds of physically 
based contact points.
If something fails, it has to be desoldered, but it's not the end of the world.
Often sockets cause the problems that units come into service for anyways.
Like a self-fulfilling prophecy ;-)

>
><...>
>
>>  Replaced transformer connections with new, gold plated mating connectors
>
>It's been quite some time since I saw one of these and I have no recollection
>of what they used for transformer connections.

3 pin molex.
The gold thing is probably overkill, but Moog didn't double up pins 
on these and I wanted some definite contaction.

>  > Replaced 25 year old, single turn adjustment trimmers with new, 25
>>  turn cermet trimmers
>
>That's a mod I've wanted to try for a long time for a minimoog,  never did get
>around to it,  though.

I do it all of the time on Minis and even have made a board design to 
retrofit them into the old trim holes.
(Someone want to make the board? ;-)
If you get a chance, definitely do this. The Mini will be a lot happier.
Putting in Holco 0.1% resistors in the CV summing areas and range 
switch circuits helps a lot too.


>
><...>
>
>  > 14 keys replaced (special weighted types)
>
>Those are the ones with a bit of birdshot in epoxy,  right?

I'm afraid that you may have read something somewhat misleading.
They have lead strips in them. I've yet to see birdshot and even 
owned a new polymoog when they came out.
In this case, the lead is removed from the old key tops and installed 
in new tops with epoxy.


>
>>  All solder used is Kester silver bearing solder
>
>Why?

While the melting temperature is a bit higher, I find the solder 
creates a stronger bond.
A bit more brittle probably, but good flow and wetting angle.
Obviously, silver is a great conductor too, though I'm not sure how 
much better sub ohm differences are going to play for most 
applications. I just happen to like it better and it definitely makes 
the connections shinier, which helps see where you've already 
soldered on large resolder jobs like these.

>  > Unit will be tested, any component level troubleshooting completed
>>  and calibrated next week.
>>
>>  Cost? I have no idea.
>>  What would YOU charge?? :)
>
>What's your time worth?

Heh... I'm not asking what I will charge.
I know this roughly.
I'm asking you guys what YOU think it's worth. :)


>  Think there's many
>of them out there still?

There's definitely some because they come here fairly regularly.

-- 
Regards,
Kevin Lightner

Myself: http://www.synthfool.com
Service and sales: http://www.moogmusic.com/service.php
Sales: http://www.cluboftheknobs.com