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m-audio slider(s)
patrickkeane Posted: 21 Nov 2020, 10:11 PM
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W2BRS

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In what may go down as my greatest eBay purchase ever, I bought an m-audio axiom 49 gen 1 keyboard on eBay for the low price of $4.25 plus shipping ($25).

Claimed to be "broken", I gave it a + - hard reboot, and it works fabulously. Ignoring its cosmetic condition, which is still perfectly fine, I note that the D9 slider is completely unresponsive, and the D14 slider is "slow" to respond to changes and also -- it bottoms out at 3, not 0.

These seem like pretty minor issues and ignorable -- but perhaps worth repairing. I suppose that D9 is a broken solder joint. D14 is more puzzling. Thoughts?

Last edit by patrickkeane at 21 Nov 2020, 10:11 PM

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DAVID Posted: 22 Nov 2020, 08:11 AM
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avrs + midi = best diy synths

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What an amazing deal you got for that keyboard. Could it be that the d14 slider needs cleaning on its track? maybe some electrical contact cleaner will do the job.

Last edit by DAVID at 22 Nov 2020, 08:11 AM

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patrickkeane Posted: 22 Nov 2020, 03:11 PM
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Well, after trying deoxit on all the sliders, I couldn't seem to make any headway with them, so I took the board out and after toning out the traces for a while, I came to the conclusion that slider 9 and 14 were just bad. So, I removed them both and swapped them. Whereas slider 14 used to be "slow etc" in position 14, after moving it to position 9, it works great. So, position 9 is perfect. Perhaps just resoldering it also helped? Hard to know.

The slider removed from 9, when moved to 14 moved the problem. This slider seems to be a goner.

Now I just need to be on the lookout for a new one, apparently made by ALPHA (stamped on the side). AliExpress doesn't seem to offer an immediate perfect matches for it, but I'll keep looking around.

Anyway, the situation is 50% improved!


(User posted image)


Last edit by patrickkeane at 22 Nov 2020, 03:11 PM

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mit Posted: 22 Nov 2020, 04:11 PM
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yeah whatever

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I have a love-hate relationship with my M-Audio Axiom 49. I also bought it on eBay and it came with a broken slider. I never did get round to repairing it, but it has enough sliders that I wasn't bothered.

The thing that bothers me the most about the keyboard is you can spend ten minutes configuring what CC each knob and slider sends, and then a single accidental press of the "zone/group" button will overwrite them all with different configuration. Sometimes changing patches will also reset their config. I have tried at least twice to read the manual and figure out how this is supposed to work.

But I really like how it's easy to toggle midi-interface mode. This is something the Keystep gets wrong, the only way to use its MIDI ports as a USB interface is to enable MIDI-Thru in its SysEx configuration software, which then merges the midi streams. What a nightmare!

I still plan to one day write my own firmware for the Keystep, it's an stm32f103 inside...

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patrickkeane Posted: 22 Nov 2020, 04:11 PM
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Well, I disassembled the potentiometer, and its definitely got NC on pin1, so -- that's a bummer.

I think I found the match on AliExpress after some digging:

https://www.aliexpress.com/item/32797661522.html?spm=a2g0o.productlist.0.0.6a3a243apzuJs4&algo_pvid=1ab1dc95-f7a9-4bfc-b5e0-395106c12d45&algo_expid=1ab1dc95-f7a9-4bfc-b5e0-395106c12d45-13&btsid=0b0a556e16060635160658134e89a4&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Its a 45mm Alpha with a strange layout, the pins are recessed in, so most others would be a mismatch. Anyway, 3 for 9 bucks, and if I order it now I might have it for Christmas. If this is the right part I will let you know Tim. The only thing to do will be to disassemble and swap the black plastic indicator with the metal one this seems to come with.

My only complaint at the moment is that disassembling it revealed at least 4 different screw sizes.

I think there are ways to lock out the zone button?
Patrick

Last edit by patrickkeane at 22 Nov 2020, 05:11 PM

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patrickkeane Posted: 8 Dec 2020, 05:12 PM
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Hey my parts arrived from AliExpress, and even while I still could remember what project they go with!

If you want to fix your slider Tim, I can confirm this is the right part. And, depending on how picky you are, you can swap out the guts to give it the right black plastic lever (vs. metal).

Anyway, since I ordered 3, I also replaced the "slow" slider. That corrected it. So, I kind of suspect that it was reading some wild values, and in order to convert from the potentiometer, it was averaging values to get a value from 1-127. And, maybe it was slow just as it tried to deal with the nutty readings.

Anyway, all fixed. Now I just need to figure out where I originally got all these screws from! As always, wishing I had made a diagram.

Oh -- And, I finally figured out what the seller meant by "midi out doesn't work". The USB connector had a lifted trace, so it would power up from USB, but not connect. Bodge wire to the rescue... DONE!

Last edit by patrickkeane at 8 Dec 2020, 10:12 PM

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mit Posted: 10 Dec 2020, 11:12 AM
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yeah whatever

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Nice work. The behaviour of my broken slider is different again: when it gets moved, it will send erratic values, and will continue to send random values for about ten seconds after you've let go.

I'll order some sliders. I think one reason I never got round to fixing it is that I did once take the keyboard apart - the USB port was broken and I fitted a new one - and I remember there being a comically high number of screws holding it together. Something like 50 screws need to be removed just to get the case open.

Contrast with the KX5, which has a metal case and I think only six M4 bolts have to be loosened to open it.

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patrickkeane Posted: 10 Dec 2020, 02:12 PM
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The case is mostly made of screws with a little plastic to hold them all together into a keyboard shape.

The tiny silver screws are interior for the PCB.
The small black screws are under the leading edge with one in the back middle.
The black narrow threaded screws make a straight line across the middle and thread into the metal support.
Everything is is the largest black screws.



Last edit by patrickkeane at 10 Dec 2020, 02:12 PM

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mit Posted: 19 Dec 2020, 02:12 PM
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yeah whatever

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Because I'm an impatient cheapskate, instead of ordering the exact same part as you I went with a different seller that was cheaper with faster shipping. Naturally, the part that turned up has the wrong footprint:

(User posted image)


Having fought my way through the 47 screws needed to disassemble the keyboard far enough to realize the mistake, I figured I'd rather drill new holes in the PCB than suffer the indignity of ordering another slider (and another reassembly cycle)

(User posted image)


I'm kind of bewildered by the PCB layout, it's sparse enough that this is possible, yet it uses loads of through-hole jumps to route things. I wonder if it was a limitation of the CAD software they were using.

(User posted image)


Underneath I just bent the legs over and soldered wires to the original pads.

(User posted image)


Keyboard is back together and it works fine, so here's hoping that's the last time I have to dismantle it.

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patrickkeane Posted: 19 Dec 2020, 02:12 PM
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Hmmm... If only you were warned!

"Its a 45mm Alpha with a strange layout, the pins are recessed in, so most others would be a mismatch."

Haha. Good work. I also hope to never open mine again. I'm told there's some tiny 3 pin surface mount reset IC that goes bad so other than the sliders, the usb port, we've both now done the other two of three major majfunctions.

Happy holidays! ☃️

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mit Posted: 19 Dec 2020, 03:12 PM
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Yep - entirely my fault for not listening.

Looking forward to that next IC failure.

Cheers!

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