K2500R bad Alpha Wheel, can this be fixed? (Resolved)

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K2500R bad Alpha Wheel, can this be fixed? (Resolved)

Post by part12studios » Mon Jul 27, 2015 9:48 pm

Hi everyone,

I am about to get my hands on a K2500R that looks to be in good shape for a very good price tonight ($75 and it has 128mb ram!) but it has one major problem.. the Alpha Wheel doesn't work.

I haven't seen the unit in person yet, but the owner said you can use the arrows to navigate (although i'm sure this is a pain). Also though thanks to MidiQuest 11 they also support the unit so I could use a computer to edit things as well via sysex.. woot.

So I'm wondering if this can be repaired? maybe the dial is very modular and pops out to be cleaned / replaced? is an alpha wheel something that can be bought / replaced? I haven't cracked it open to know first hand. I'd be willing to invest a little money into fixing it up potentially but I'm not having much luck finding parts.

I know a local repair guy that probably could fix it but i want to explore the DIY route first and educate myself on the unit before i go hiring him. I'm still feeling pretty brave having recently repaired a 2032 battery on my K1m.. heh heh.. a real Robert Moog right here. ;)
Last edited by part12studios on Tue Aug 22, 2017 3:18 am, edited 1 time in total.

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by splitpoint » Tue Jul 28, 2015 10:59 pm

Had an E4k with the same issue, I ran calibration and fixed it right up. I'll be the first to admit I know nothing about the k2xxx series but before you go digging into the hardware you might check to see if there is a calibration menu option available for the alpha wheel. If that doesn't work it might be worth trying some deoxit on the encoder.
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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Tue Jul 28, 2015 11:11 pm

thanks that's encouraging! i'll dig deeper. i agree it seems like it should work..i mean it responds to turns.. just seems to not advance.. so it's working in a way.. i mean really.. how is it possible to advance the direction it could and yet snap back to it's origin.. why not just move to the next spot?

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by synthroom » Wed Jul 29, 2015 6:31 pm

There's a KX00 forum on Yahoo - there's a lot of activity there and a lot of knowledge about repairs. Try signing up there and asking.

For $75, I'd grab it. I have a K2000 and it is a very cool sounding machine. Go to Sweetwater's site as they have lots of info and sound data there. Load in the Dark Side of the Moon patch from there and be amazed at what flexibility those machines have.
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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Wed Jul 29, 2015 7:02 pm

how do i find that group? i didn't have any luck googling kx00..

yea $75 is worth jumping on it if parts are scarce. Where did you see a deal like that? I left a voice mail with some US official service company for Kurzweil but they haven't called me back. I doubt i'd be willing to pay someone to fix it.. the +/- makes it ok really..

the bad R channel bothers me more. I'd really like to know all the output work right. using the headphone out to get stereo sound is less cool than a bad alpha wheel. :) (correction stereo out is fine.. it turned out it was a bad patch bay cable.. so yes it's just down to getting the Wheel working now to be 100%.. what a relief)

I'll check out the site! This thing is a beast and i love the sounds built into it.. i'm very excited to see how it stacks up to the ESI-32 as a sampler.

as for calibration there isn't anything like that with the K2500.. they have an test mode which allows you to test buttons and such.. but nothing in there so far about calibrating.. i remember the volume knob on the ESI-32 has a calibration... in fact that's how i fixed what for some time was a seemingly no audio output device..

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by synthroom » Thu Jul 30, 2015 12:28 am

KX00, where X=0, 5, 6

Search for K2000, K2500, or K2600 or Kurzweil.

I get:
https://groups.yahoo.com/neo/groups/KurzList/info

I have not pulled the wheel out of my K2000S, but here's what mine looks like with the bottom panel removed. The alpha wheel is on the left side under the large circuit board.
http://synthroom.com/wordpress/wp-conte ... -01985.jpg

Are you saying:
1) the wheel turns and then physically snaps back to the original spot, or
2) the wheel turns and the data increments but them returns to the original data value?

The cool thing about the K2000/2500/2600 is that it's not a sampler, it's a synth that samples. It's like the Roland V-Synth, I think, but 10 years ahead of it.
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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Thu Jul 30, 2015 2:17 am

I found a general user group I posted but it doesn't have many users on it.. gearslutz had some tips but the general consensus seems to be it's not something that can be fixed through calibration or other DIY approach..

as you can see this part is seriously wedged inside the front panel.. i'd dare say it's more tricky to get too than the screen on the ESI-32..

Image

Image

So yea I think i'll leave well enough alone, but i did track down a local service company and will talk with them tomorrow to see what they say the price will be. If it was easy for me to just undo a few screws and pop the wheel out i'd be willing to try but it looks pretty interdependent.. if the unit were useless without the knob i'd be more daring..


About the knob.. the knob turns and feels great.. it's the digital side of things. here is a video to show it in action:




Yea it sounds great. i believe I'll be putting some work into understanding this one deeper.

unfortunately this unit, while pretty darn decked out.. it doesn't have the nicer effects processor upgrade that's out there apparently. i'd love to upgrade to that but it's not looking like those parts are easy to come by. However I am going to keep at it to see if i can find one for a reasonable price..

http://www.soundonsound.com/sos/jan99/a ... fx.159.htm

Thanks,
Caleb

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by synthroom » Thu Jul 30, 2015 3:20 pm

I have no clue how the wheel works, but have you tried blasting it with a can of Dust-Off or whatever your favorite brand of compressed air/Freon/fluorocarbon is? Blast and spin the wheel, maybe something's caught in it.
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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Thu Jul 30, 2015 4:19 pm

yea i got an interesting snippet of insight into it, though i couldn't find any videos that explain this:

"It hss a worn rotary encoder or 1 bit encoder. They are a common part on a lot of products. Couple bucks to 10 bucks. Three solder joints, and one nut, after removing lid then fron panel and spin knob with an Allen wrench. Easy job of simple basic skills and basic electronic hand tools."

So I might consider going this route some day when I have more time, but there are so many options right now that allow me to bypass the knob that this is likely to be a backburner project. my main question was "can i fix this easy?" and that seems to be "No" and I'm ok with that.

This one guy is offering the whole front replacement (without screen) for $85 with shipping.. and that's reasonable.. but it's replacing the whole front board.. kinda overkill..

a local repair place offered to fix it for $200 estimate (hasn't looked at the unit) and it would be $45 for him to look at it. So you know.. i'm just not feeling like anything more than $50 to have it working is worthwhile.. maybe way till something more significant breaks to justify spending that kind of money on what is really just a convenience..

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by abruzzi » Fri Jul 31, 2015 5:00 am

Before replacing the encoder, slide the wheel off (pull it straight out) and spray deoxit on the shaft. Wipe off the excess, then try spinning the wheel. Repeat a few times to see if it improves the reading of the encoder. If it fixes it, then dab a tiny bit of petroleum jelly around the shaft, and slide the wheel back on.

I've done that to mine.

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Fri Jul 31, 2015 5:42 am

will do! yea it kills me to think that it's not some simple fix like that. the fact that it responds so well and turns nicely.. its like.. man.. there must be a way.

So deoxit, I don't have any of that.. know any stores that would likely carry it? or maybe there is some other suitable equivalent sold at local retail (otherwise i need to mail order some)


Side Question.. anyone know how i can tell what revision a particular K2500 is?

i have a guy i'm talking too about the wheel / front panel board.. (trust me i'm going to try your tip first) but he said the card is Rev C.. my understanding is that matching Rev's is important so if i buy it and I have A or B.. it may not work.

The bootup shows 2.52.. it has several modules in it.. sampler.. digital i/o (XLR?) / optical in / out.



Thanks!
Caleb

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by synthroom » Fri Jul 31, 2015 6:20 am

On the K2000 there's two ROM versions, Janis for later ones and Calvin for earlier. Each one has multiple revisions. Then the OS runs on top of that.
I hate to think they did something like that with the 2500...
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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Fri Jul 31, 2015 2:58 pm

so my search so far has come up empty for this particular brand.. but i assume deoxit is a contact cleaner and would getting another alternate brand be ok or is there something very specific about this product that is superior to the others as general electronics contact cleaner?

I'd love to do this treatment today, but i just don't want to buy the wrong product.

Thanks,
Caleb

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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by synthroom » Sat Aug 01, 2015 4:47 am

http://www.caig.com/

Available at better electronics shops everywhere. Even Radio Shack, if there's any still around in your neck of the woods.
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Re: K2500R bad Alpha Wheel, can this be fixed?

Post by part12studios » Sat Aug 01, 2015 5:01 am

i'm just going to order some online.. nothing like that around here anymore.. i know of some places in the city but i'll just order the right stuff and know i'm getting it. i called around and no one carried that particular brand. there were places like guitar center that sold "contact cleaner" but not this particular brand.

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