mod wheel fix

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filtered
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mod wheel fix

Post by filtered » Wed Mar 20, 2013 1:32 pm

Hey! So, my mod wheel got bumped pretty hard, and wasn't staying in place when I'd nudge it up for just a smidge of whatever- If not up all the way, it'd slowly fall back to zero-
SO, I opened it up and messed with the pot, and yep, now it doesn't function- :roll: I've been getting by by just using the amount knob, but of course want to get my mod wheel back in action-
My question is, is the pot purchasable by itself? Or is there a decent alternate manufacturer out there that sells a pot with those specs?
thanks for ANY info!
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Re: mod wheel fix

Post by Vsyevolod » Wed Mar 20, 2013 2:42 pm

You of course tried contacting Moog Music about this first? They would have definitive answers...

Stephen




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thealien666
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Re: mod wheel fix

Post by thealien666 » Thu Mar 21, 2013 7:52 am

...and they certainly would have the exact replacement part, too! :wink:
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Re: mod wheel fix

Post by muksys » Thu Mar 21, 2013 8:57 am

I haven't looked at it closely, but wouldn't it just be a standard Alpha Pot? It should have the value on it. They can be ordered from virtually any supply house. I'm a fan of Jameco for stuff like that.

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Re: mod wheel fix

Post by filtered » Thu Mar 21, 2013 11:46 am

yeah I'll give them a call... thanks
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Re: mod wheel fix

Post by thealien666 » Thu Mar 21, 2013 2:19 pm

muksys wrote:I haven't looked at it closely, but wouldn't it just be a standard Alpha Pot? It should have the value on it. They can be ordered from virtually any supply house. I'm a fan of Jameco for stuff like that.



Yeah, it's a regular Alpha pot, like all the others inside the Voyager. The only thing that I don't know is its value and type (audio taper or linear).
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Re: mod wheel fix

Post by muksys » Thu Mar 21, 2013 6:04 pm

thealien666 wrote:
muksys wrote:I haven't looked at it closely, but wouldn't it just be a standard Alpha Pot? It should have the value on it. They can be ordered from virtually any supply house. I'm a fan of Jameco for stuff like that.



Yeah, it's a regular Alpha pot, like all the others inside the Voyager. The only thing that I don't know is its value and type (audio taper or linear).



Should be easy to see. Just pull it out :shock: er, I mean remove it and take a gander. My guess is a 100k linear.

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Re: mod wheel fix

Post by thealien666 » Thu Mar 21, 2013 6:23 pm

On a Minimoog D it's a 50k audio taper, but that's not necessarily, and most probably not, the same on a Voyager.
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Re: mod wheel fix

Post by CZ Rider » Thu Mar 21, 2013 7:17 pm

Have an older set here, so newer Voyagers may use a different manufacturer. Uses a Bourns #3852A-282-103A for both pitch and mod. It's a 10K cermet type linear.
Not sure what they use now, but that part comes up as obsolete, non-ROHS. Unknown what the new number or replacement part is. I'm on my third set of wheels, so they are not very robust. Actually had one seize up with little plastic shards falling out.
Next time I replace these, I'll go with the old military spec Allen/Bradly type J pots. They last a lot longer and the ones in my Moog from 1969 still work great and won't fall apart just because I use them. LOL!
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Re: mod wheel fix

Post by thealien666 » Thu Mar 21, 2013 8:58 pm

Yeah, those Allen-Bradley were military grade ! I only had to open the one for the mod wheel on my Mini, to invert the carbon wiper that had become unevenly worn at a 45 degree angle. I expect it could be good for another 10 years or so...

BTW, Allen-Bradley was bought many years ago by Honeywell. But the company still makes the same kind of high grade sealed type pots. They're pretty expensive though...
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Re: mod wheel fix

Post by filtered » Fri Mar 22, 2013 9:50 am

So yes, Allen/Bradly type J pots- I'd rather go robust! There're a ton on the Bay, but what exactly would I be looking for? Thanks!
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Re: mod wheel fix

Post by thealien666 » Fri Mar 22, 2013 1:29 pm

Same resistance value, and same type (audio taper or linear) as the one presently in your Old School, and one with the same length an diameter shaft.

Important note: As Kevin Lightner would probably point out, the Allen-Bradley Type-J do not go down to precisely 0 ohm at their minimum position. There will always be some residual resistance due to the carbon wiper used in the design. So, depending on how the modulation signal is passed thru this pot, you might end-up being unable to completely remove all the modulation with the mod wheel all the way down after having replaced the regular (presumably Alpha) pot in that circuit. On the Minimoog D, this has been a design flaw from the start, that was never corrected. There is always a very slight modulation bleeding with the mod wheel fully down. That's because on the Mini, the full modulation is always present, and the mod wheel acts as an attenuator. Whereas in some other circuit designs, presumably the Voyager, it might be the opposite, the modulation might be increased by the mod wheel instead of shut down. And that might make the bleeding a little less noticeable.
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Re: mod wheel fix

Post by CZ Rider » Fri Mar 22, 2013 4:24 pm

Just tried to replace those cheapo bourns with some proper AB type J pots. Everything looked good as far as space, just enough room to fit. And the shaft and threaded sleeve were the same dimensions. But the extra wide diameter body on the type J is just a little too large for the L mounting bracket.
Image
Too bad! The L bracket mounting hole could be enlarged a tiny bit, but it will effect the geometry of the wheel movement. Perhaps making the clearance of the wheel too close to the cutout. It does not miss by much, but the bracket needs to be altered to fit type J pots. I'm still going to go ahead and mod a set of wheels to the old Moog standard. Might even try Mini wheels, never did like those fat wheels and prefer a detent to a spring.
But I do have two sets of exploded LH controllers to experiment with. The way my Voyager is now is unacceptable. It is never in tune because the pitch wheel never gets to the same zero point. Can see it on a MIDI monitor, sometimes it stops at 32, sometimes at -17. My guess is this dates back to when to Voyager was introduced. The first units people complained there was a dead spot on the ptch wheel, making proper vibratos impossible. So they took away the dead spot. This is not that noticable if you always set the pitch wheel to a few semitones. But set to a fifth or an octave, it becomes an issue.
Oh well the part number is above for the replacement Bourns. The AB part I am using is JA1N056S103UA. When I find a non Bourns solution, I will post it. I'm sure there are other heavy duty pots that would work.
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Re: mod wheel fix

Post by thealien666 » Fri Mar 22, 2013 5:00 pm

Very interesting CZ Rider...

But if I remember right, my Voyager Old School had a slight dead zone on the pitch bend... I could be wrong, because I sold it a few years ago, (along with my EB model too) and don't have any Voyager now...

BTW, Bourns do offer industrial grade conductive plastics type pots, that are probably a little smaller than those big A-B Type-J ...
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Re: mod wheel fix

Post by CZ Rider » Fri Mar 22, 2013 5:45 pm

thealien666 wrote:But if I remember right, my Voyager Old School had a slight dead zone on the pitch bend...

That could very well be. The Voyager I have here is a PE, so the pitch wheel is digitally scanned and noticable on the MIDI output. Could be the OS is a completly different circuit. Got my Voyager in 2005, and was a little pissed that they later offered the OS. Not a big fan of DCA's. (Digital Controlled Anaolg).
Not an engineer, but there seems to be a lot of torsional load on the potentiometer, in that type of setup. Probably the reason the mod wheel pot broke. Even the L brackets are not as robust as they could be. When my Voyager arrived the wheels were not straight, but were easily bent back into position. There are smaller AB mod pots too. I would look for one with a sleeved bushing on the shaft. But you can see from the photos, those Bourns types they are using do not look like they can handle the repeated stress. Depends on how much you use the wheels too. The mileage on a set of wheels I use could be many times what another user might have, but I wore out two sets of those Bourns pots.
The OD on those type J pots was 1.090". A little buzz with a Dremel will enlogate the mounting hole enough to fit these in place, but I can not recommend anyone else to try this. Just that I can do it without any expense, I have all the spare parts here. But I am not going to try to replace them with the same set of pots that are known to fail me.
Wish I had a better solution for Filtered. But the type J pots won't fit without altering.
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