Just bought a Model D on eBay...

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TOS
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Re: Just bought a Model D on eBay...

Post by TOS » Fri Feb 12, 2016 2:34 pm

Some concerning things in this thread, and like Tom I think I need to up my rates!

The pots are delicate (a material that chips easily was used) so extreme care is needed to ease the metal back off for cleaning. The pots resistance strip was sputtered onto this substrate which is an insulator, and a chip may take a section of the resistance strip with it. Some folks drill a hole for cleaning with a very short drill but you risk metal swarf getting in there.

I do not like the look of the small section of this buss-bar/contact assembly in the picture. I'm seeing disfigured springs, melt (from a soldering iron) on a buss-bar support, maybe solder on the buss-bar near this melt. I'm also not seeing the gold coating on the springs but I expect that is because the camera flash not giving a good picture. Its hard to get these original contact assemblies to work reliably when there is mangling of the springs/ heavy oxidization. Might need so contact springs replacing but I guess your labor and parts bill will increase.

Chris Hewitt

This Old Synth
This Old Synth, the new home of Synthfool's Opto-Key project.
www.thisoldsynth.com

Spumoni
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Joined: Mon Nov 07, 2011 9:36 am

Re: Just bought a Model D on eBay...

Post by Spumoni » Sat Feb 13, 2016 12:10 pm

Thanks for the feedback - it's always good to hear from experienced folks.

Not sure what I should do at this point, since the work is already complete. They are leveling the keys now, and it should be complete. I was also concerned when I saw the picture because those burn marks were not there before. I was also concerned once I realized what "cutting the pots" meant, but they claim it's standard practice, and makes future cleaning easier which makes sense.

I'm assuming that buss-bar/contact assembly is original, and probably difficult to replace? Would going to an optical system eliminate this ugly mess, or am I better off keeping it as original as possible?

Thanks for all the feedback, even though it's scaring the bleep out of me!

How funny... it automatically changed "bleep" to "bleep". bleep. bleep.

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thealien666
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Re: Just bought a Model D on eBay...

Post by thealien666 » Sat Feb 13, 2016 12:55 pm

Yeah, going optical would definitely resolve the keyboard issues once and for all. It's not exactly cheap either, but totally worth it. I've done it on mine and never looked back.
Now, IF they really did a good job on the original key contacts, it should last for a while before it becomes problematic again (and it eventually will), and that could leave you enough time to save some money for the optical system to be installed later on.

Just curious, how long since you've left your Minimoog in the hands of Analog Lab again ? Because replacing bushings, cleaning the pots (most of which, from experience, are usually self-cleaning by simply working them out because of the way they're made inside and sealed) and switches, straightening the buss bars and coil springs shouldn't take more than a week at the most. Especially at the rates they're charging you...

Alain.

(I was surprised to read that "bullshit", in my previous message, wasn't automatically changed to "bullbleep" ... :lol:)
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion

Spumoni
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Re: Just bought a Model D on eBay...

Post by Spumoni » Sat Feb 13, 2016 1:20 pm

Hello Alain - They've had the unit for about 2 weeks, but they originally told me it would take 2-3 weeks, so I'm not worried so much about that. Do you think it was a mistake to have the pots cut, even though it makes them easier to clean in the future?

I will probably get an estimate on the optical system, I really don't want to keep sending it out, especially once I refinish it!

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thealien666
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Re: Just bought a Model D on eBay...

Post by thealien666 » Sat Feb 13, 2016 1:52 pm

It all depends on how they went about "cutting them open". Normally, a good repairman will simply fold back the tabs holding the back cover in place (see picture below), in order to be able to put it back.

But if they actually cut the metal casing with a cutter, I don't know how they could re-seal the back cover in place ?

Image

Note: photo not of a Minimoog potentiometer, but a similar sealed one.
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion

TOS
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Re: Just bought a Model D on eBay...

Post by TOS » Sat Feb 13, 2016 7:59 pm

The burn marks on the bridges are not an issue in themselves (apart from cosmetics), but show soldering has been done from the actuator side of the assembly. I have seen this where folks have tried to deal with bad contact springs by soldering the lower section of the spring.

Fingers crossed that everything works nicely!

You should test the keyboard before you take it away. Look for "squirelly" keys where the note frequency changes erratically while a key is held. Just have one oscillator running for this. All other switches and controls to 0. Do these tests:

1/ Set it with no modulation, Cut-off +5, Emphasis and contour 0. Set the Loudness Contour for a short attack such that the notes played are percussive. Play every key with both slow and gently presses, and faster harder ones. Make sure they all play and trigger cleanly.

2/ Increase the attack a bit and set loudness sustain full on, try it again.

3/ This is the most critical one and it needs the note to sustain... hold down the rightmost High C key. While keeping the High C held down to keep the note sounding, press each key from right High B to Low F checking the new note plays and triggers cleanly, and that as you release the key it goes cleanly back to high C.

I clean and adjust the contacts until I can achieve this, but also leave it a few days and try it again, then test regularly. MiniMoogs here therefore tend to be on burn-in test for at least a week. Note that the contact springs need to be in good physical condition in order to be able to clean them and get them going. I have seen a number of buss-bars recently that have been aggressively cleaned to the point that the gold plating has been removed. I of course prefer Opto-Key to messing around with these contacts for endless hours.

Hope things work out for you!

Chris Hewitt

This Old Synth
This Old Synth, the new home of Synthfool's Opto-Key project.
www.thisoldsynth.com

Spumoni
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Re: Just bought a Model D on eBay...

Post by Spumoni » Sun Feb 14, 2016 11:58 am

Alain /Chris:

Thanks for taking the time to explain all of this. Chris, I actually came across your site when I was looking for service centers, but chose Analog Lab because they were in the same state. My intent is to have an unmolested mostly original minimoog that I can keep and enjoy for a long time, and something that looks spotless both outside and inside.

Assuming the cut pots aren't really an issue (are they?), the only other "ugliness" is that burnt looking buss-bar section. My main regret is that I would have certainly opted for the opto-key before they spent the hours trying to repair each and every key contact. But they seemed very confident it would last a long time. I will ask them to perform this test, or just do it myself when I get it back.

Chris - I looked at the opto-key info on your site and It appears as though this is something I can do myself the the time comes, correct? This would definitely be my back up.

Alain - thanks for the picture/explanation of the sealed pot. Looks easy enough to remove the covers, but it's already been done. Hopefully they were cut properly - I will certainly find out more and keep you posted with pictures.

Thanks again for all this info. This is very helpful.

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thealien666
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Re: Just bought a Model D on eBay...

Post by thealien666 » Sun Feb 14, 2016 1:56 pm

You're welcome Spumoni.

The Opto-Key can be installed by yourself (that's what I did to save some money) relatively easily (no holes to drill or anything like that). And since your Minimoog will have brand new bushings and freshly levelled keys, it will be an excellent candidate for the Opto-Key eventually. BTW, it's was cleverly designed (by Kevin Lightner RIP) to be totally transparent and not modify the Minimoog in any way. When installed, nobody can tell that it's inside, unless they open the bottom of the synth and see it.

Anyway, I hope you get your Mini back in good shape. And, as stated earlier, if Analog Labs did a proper job it should work fine for a while before the key contacts become an issue again.

Cheers,
Alain.
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion

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noddyspuncture
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Re: Just bought a Model D on eBay...

Post by noddyspuncture » Sun Feb 14, 2016 2:44 pm

TOS wrote:The burn marks on the bridges are not an issue in themselves (apart from cosmetics), but show soldering has been done from the actuator side of the assembly. I have seen this where folks have tried to deal with bad contact springs by soldering the lower section of the spring.


And the solder travels up inside it - due to capillary action - and you then have a solid rod... with hopefully a bendy bit at the top... aaargh!
:?

Cheerz,
Tom

obscure wave music
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Re: Just bought a Model D on eBay...

Post by obscure wave music » Sun Feb 14, 2016 6:21 pm

Hi everyone,

I'd like to get back to the beginning of this thread. Unless I missed something along the way, Spumoni's
Mini behaved normally by the looks of the video made by the original owner. How then can it be that
his Mini was so bad when he got it ? Was it the same Mini as in the video ? It was very well packed, according to Spumoni, so the shipping should not have altered it that much....I think the seller screwed him, and if this proves to be the case, the seller should be exposed. It really seems to be evilbay these days, sadly....

TOS
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Re: Just bought a Model D on eBay...

Post by TOS » Mon Feb 15, 2016 12:49 pm

The rubber mounts that support to key contact board had perished. This is really common and a mini could work in one location but when shipped the mounts fall apart. In this case it looks like someone (maybe the seller or whoever previously sold it to the seller) had seen this and put screws through the circuit holes into the remnants of the rubber mount. This was a bodge and had a high likelihood of falling apart during shipping, especially international shipping where it had a lot of handling. On top of that there are key contact issues, which a a constant maintenance issue on the mini.

There is potential for the buyer to go back to the seller re such issues, but here the repairer has already started work on it so it can't be simply(!) returned for refund. Spumoni should contact the seller and see if something can be worked out.

I had a mini in last December that the buyer paid $8k for as "serviced and perfect". It had the same perished and broken rubber mounts, plus the buss-bars and springs which looked super clean and shiny had in fact been cleaned to the point that the cold coating had gone so it was "squirelly". In this case the seller came good and re-reimbursed the buyer for the cost of Opto-key MIDI and its install.

Hope this helps.

Chris Hewitt

This Old Synth
This Old Synth, the new home of Synthfool's Opto-Key project.
www.thisoldsynth.com

mikeh11
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Re: Just bought a Model D on eBay...

Post by mikeh11 » Mon Feb 15, 2016 3:16 pm

On some keys, the notes sound like they are gliding off into space.

That sounds like the wire-springs for the trigger bus made contact, but the ones for the pitch did not. Then you trigger a note, but the voltage for the pitch just floats - mine would float upwards, also.

As for not getting a decay on the envelopes - you've tried different positions for the Decay switch by the mod-wheels? With Decay off, the envelopes stop abruptly, which is nice sometimes. (I miss it on the Sub 37.)

(Oh, man, did I screw up -- I thought I was responding to a recent post, but I'm only about a month off! Sorry!)
MBP 2012 | OS X 10.11.6 | Sub 37 #6768

Spumoni
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Re: Just bought a Model D on eBay...

Post by Spumoni » Wed Feb 17, 2016 8:37 pm

No worries, and thanks again to everyone for the feedback. It's very helpful.

I can confidently say the owner was NOT at fault. When the unit was shipped, the screws holding the contact board had ALL come loose. As I learned, the contact board is normally held on with rubber grommets. Whoever serviced it put screws into dry rotted rubber. I reassembled all 8 screws before shipping it to Analog Lab. All 8 screws came loose again.

All of the other issues were due to extremely dirty pots and switches.

I'll keep everyone posted once I receive it back.

Again, the seller really was receptive, and very willing to help.

Spumoni
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Re: Just bought a Model D on eBay...

Post by Spumoni » Mon Feb 29, 2016 11:58 pm

The unit is finally complete. Here's the list of what was completed:

Unit Dis­assembled, Keyboard removed.
KyBd PCB Key contact removed. Old broken PCB supports removed. NOS mounts installed.
PCB re­installed key contacts fitted between Buss bars. Keyboard previously re­bushed by others Key contacts adjusted. Molex connector cleaned
On test some notes not playing, Links fitted to bypass cracked Keying PCB ON Investigation Circuit board removed, the key contacts are a lousy type that the solder does not want to take too. Completely re­soldered to make OK. Board re­installed again Contacts adjusted again.& again Suspect all key contacts have been replaced
Circuit boards removed. Controls cut open and cleaned. Switches cleaned
Edge connectors cleaned,
Power Supply smoothing Capacitors replaced.
Full calibration
Audio Function Good
----------------------------

My only regret, and I really can't blame them, is the labor spent on repairing the key contacts. They ended up taking the key bed out several times, and soldering each and every key contact. He suspected that somebody replaced the key contacts and used guitar wire??? which he explained was commonly used. This would explain why it didn't take too well to his solder. Had I known it was going to be this involved, I would have certainly opted for the opto-key, which I may end up doing regardless. Since I'm refinishing the cabinet, I'm thinking it would be a good time for me to install the upgrade myself.

I'm thinking that I will purchase the opto-key with the the midi, and not install the wires - this way I have it if I ever change my mind. Any reason I shouldn't bite the bullet and do this now?

EricK
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Re: Just bought a Model D on eBay...

Post by EricK » Tue Mar 01, 2016 1:42 am

Maybe just spend some time with it first. They may have done a great job on the contacts, no sense in spending all that money on labor just to turn around and install the Optokey components. Just play it regularly and do the best you can to keep the dust of of it.
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