Moog Prodigy restoration...

[claire.foxx]

You are indeed very lucky there as that kind of board-mounted knob is pretty easy to damage unlike say a Minimoog, Korg MS20 etc where the pots are actually bolted to the front panel. It was rare to find one that has never needed a fix even back when I was buying/selling the things 25 years ago! Nice Nippon Chemicon caps too, which are likely still mostly ok! How’s the tuning/keyboard tracking and long-term pitch stability?

I’ve set a day aside next week to check that over (the process with a multimeter and chromatic tuner is shown in one of the next instalment of the restoration videos I linked to), it’s only just been stripped, but a cursory tinkle on the plastics reveals a Middle C is still a Middle C after an hour and the pitch and modwheel centres to about 1/32 of a stop accuracy so it detents back mechanically to acceptable parameters so I am hopeful the electronics are as good as the mechanics.

Earlier models just had the pot side tags folded in but this has the proper grounding tags soldered in place. Harder to desolder to remove and strip and clean when this happens but more stable. Fortunately I don’t have to, I don’t think.

Sometimes the externals don’t reflect the internals. Got that horrible glue out of the wood channels without drama (heatgun loosens it up nicely - GORT Did not know this in his video but I picked up on it in the comments) and I will begin sanding/oiling today. I’m trying to avoid anything too invasive.

I am shying away from adding MIDI and CV/Trig retrofits even though it is the done thing, there is something about keeping it as it is — but cleaner.

First bath complete, drying off. “Hey mom? what’s cooking?”

 

[claire.foxx]

Today Miss Mërg P.Orgidee (for she has been dubbed thusly) is getting another bath, another scrub and some more attempts to get the very last of the black paint from the back edges of the panel she is soaking while I scrape the last of the glue from the rear channels of the wood in prep for a sanding and to get that top layer stuff off. Yeah I noticed the Zebrano block from a prior build too. Yeah I am thinking what you might possibly be thinking. If I were more inclined to mod or if the woods were not recoverable I would definitely make me a Zebrano case, (something every Korg MS10/20 needs is wooden cheeks to replace the shitty plastic ones on the originals and on the reissues), but no, this is a restoration job, not a souping up mod-job.

Dyson is looming, looking for scraps to eat.

Perhaps this thread is too off-topic to be in /off-topic and ought to be moved to /diy where it better suits the climate. Dunno, up to the mojitation team I guess.

 

[Tony L]

I'm more inclined to stick it in 'classic', vintage synths are welcome there IMO!

 

[claire.foxx]

Do It, Do It, Do It!

 

[stephen bennett]

Maybe we need a Musician’s lounge Tony?

Musicians with an interest in hi-fi are, in my experience, a rare breed.

Stephen

 

[claire.foxx]

I am finding someone who can lend me a sanding machine to finish this off... scraper and 60 grit seems to do well but I want a cleaner dent free finish and sand back to wood — I don’t have the muscle I used to have to do this by hand. Found some drawing pin holes on the back edge and some very minor cracking, shellac (or whatever this was) hides a multitude of sins. Still, early indications are it’s going to look lovely. If I can just keep the wood pale...

 

[Tony L]

It is going to look superb. I always liked the Prodigy, though had no use for one as it had no CV & gate input. Had a couple quickly pass through. One of those synths that is so clearly and simply laid out you can learn it real fast and set it up blind/know exactly what every knob tweak is going to do and how to get back etc. My equivalent and one of my favourite synths ever for that reason was the Roland SH-2 (kind of an SH-09 with an extra oscillator). Another one I wished I’d kept!

 

[claire.foxx]

I might keep this one* precisely because it has no MIDI and no innate connection to the outside world, it is what it is, and is it’s own thing: like a bass or a simple melody line machine, very hands on. Midi/CV/Trig etc would be fun for sequencing while I play guitar and bass lines and sing — but it’s not a dealbreaker.

*No guarantees on this as I am always shifting plans and ideas< but if it fits into the band, then yeah, it’s a keeper.

 

[Cesare]

That's a lovely restoration job you are doing there Claire - i'd certainly try and avoid 'improving' something like this. It's been ok for the previous 40 years without midi, so chances are it'll stay useful for another 40 if you just give it a bit of a clean.

 

[Moggi1964]

I keep coming back to this thread to write something profound and all I can manage every time is WOW so I figured I should just post that.

Awesome piece of history being lovingly restored. Perfect!

 

[Marchbanks]

I’d love to try somthing like this - unfortunately I’m so maladroit that anything that dared to go that close to Coffee Corner would immediately be gunked up with wet grounds and brown puddles. Even if I was nowhere near at the time, I swear.

 

[Jono_13]

I’ve set a day aside next week to check that over (the process with a multimeter and chromatic tuner is shown in one of the next instalment of the restoration videos I linked to), it’s only just been stripped, but a cursory tinkle on the plastics reveals a Middle C is still a Middle C after an hour and the pitch and modwheel centres to about 1/32 of a stop accuracy so it detents back mechanically to acceptable parameters so I am hopeful the electronics are as good as the mechanics.

Earlier models just had the pot side tags folded in but this has the proper grounding tags soldered in place. Harder to desolder to remove and strip and clean when this happens but more stable. Fortunately I don’t have to, I don’t think.

Sometimes the externals don’t reflect the internals. Got that horrible glue out of the wood channels without drama (heatgun loosens it up nicely - GORT Did not know this in his video but I picked up on it in the comments) and I will begin sanding/oiling today. I’m trying to avoid anything too invasive.

I am shying away from adding MIDI and CV/Trig retrofits even though it is the done thing, there is something about keeping it as it is — but cleaner.

First bath complete, drying off. “Hey mom? what’s cooking?”

Quality use of an Aga, ten house points!!

 

[337alant]

Excellent restoration job, I really like the look of that
I would change those electrolytic capacitors and treat all the pots and switched with a cleaner / lubricant such as Deoxit D5

Alan

 

[claire.foxx]

Yes, I thought long and hard about this one: There is a lot of bad blood in a vintage synth repair group currently about the blanket changing of all electrolytic caps. The thread got closed because it got nasty. People advocating swapping ALL the ‘lytics (usually people like me, not n00bs to electronics but new to old synth restoration) vs people (usually the pro repair/restoration guys) swapping only where it is needed or not at all because the capacitors are signal-affecting and they still read ok.

It’s a toss up on PSU rectification smoothing caps. Some people also advocate changing the Vregs for higher current capacity and therefore cooler running. i’m going to leave it for now for consideration once assembled with a new U.K. transformer and see how I feel when it approaches completion.

The pots are in good shape and working, to service them would require desoldering, taking off and pulling apart (no air or service port on those). I feel it best to leave it alone. It’s not yet broken.

 

[Tony L]

If you are in any doubt I’d just pull a couple of caps at random and test them. Nippon Chemicon have an excellent reputation, one of the brands known for lasting very well.

Here’s a video from ‘Curious Marc’, who is one of the most knowledgeable and respected electronics engineers in the vintage computing community (his videos are superb!), and he has a very balanced view of this subject based on dealing with caps far older than one would find in any Moog (e.g. IBM mainframes etc).

 

[Yomanze]

Look inside my AKAI S1100 sampler, *forget* recapping that beast. Still works like a champ.

On the Moog Prodigy, what a gnarly beast that is. One of my favourites.

 

[claire.foxx]

It might just become a bass synth for me, it’s so hands on...

Recapping isn’t necessary a lot of the times it is done, I know we are raised on a diet of Naim edge-of-the-seat stuff, but in situations where the ambient temperature remains cool, not switched on all the time and as Tony says with good quality capacitors (these are of a time long before the dreaded capacitor plague of the 1990s) I am inclined to just not fix anything until it breaks.

 

[claire.foxx]

Got me some sanded clean pale wood cheeks, all oiled (rather than varnish/stain) finishing oil is drying right now.

 

[337alant]

It might just become a bass synth for me, it’s so hands on...

Recapping isn’t necessary a lot of the times it is done, I know we are raised on a diet of Naim edge-of-the-seat stuff, but in situations where the ambient temperature remains cool, not switched on all the time and as Tony says with good quality capacitors (these are of a time long before the dreaded capacitor plague of the 1990s) I am inclined to just not fix anything until it breaks.

Clair
Its a long standing debate to recap or not and I am fine with whatever people are happy with.
I dont recap everything but I work on R2R tape machines from the 70-90s so thats 30-50 years old, caps are rated at Time at temperature so after that period of time its no surprise that approx 1 in 5 are out of spec some leaking badly and some short or way out of spec.
Note that a cap not being used for years is probably worse than a cap in constant use as electrolytic caps are self healing and reforming by constant use .
Stripping a R2R is sometime complex so I dont want to keep repeating that operation everytime it fails and I also do want to risk a shorted cap allowing DC into AC circuits where they can do damge to other components or unobtainium ICs, so I do it whilst I am there and allways with good quality caps that will last another 30 years I hope
Anyway just my view but still admiring the Moog its class one of my grand daughter's Rosie would love the play with that, probably drive me nuts with it though as well LOL

alan

 

[TimF]

Hell with the damn synth pics, I want to see those bitchin’ nails, Claire! Nice job as always on the rebuild though!