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Author Topic: KeyLab MKII "Random" Sliders - solved  (Read 2116 times)

amonti

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KeyLab MKII "Random" Sliders - solved
« on: January 06, 2022, 09:49:22 pm »
I think I can clear up the many, many threads on KeyLab slider/CC/MIDI woes/random keys/resets, etc. Last night, I watched my KeyLab stop responding to notes, sending random CCs and then locking up completely. I started Analog Lab and watched the dynamic feedback as I played and manipulated all sliders, keys, and and knobs. I noticed that whenever fader 1 was pulled to zero (completely down), it started "randomly" jumping around between values, which caused all kinds of other issues (random notes, for example). This isn't really new - many people have pointed this out. What I did, however, is completely disassemble the unit, desolder fader 1, and disassemble fader 1 to look at what the issue really was (I previously tried compressed air and fader cleaner and lube to no effect).

What I found was that while the carbon trace and wiper on the linear potentiometer were clean and in good shape, the "connecting" trace at the bottom of the potentiometer board was covered in oxidation. When I carefully bench tested the potentiometer, the resistance perfectly matched the other working potentiometers until the very last few millimetres of travel - where the carbon trace ends and the connecting trace begins. Here, the resistance wildly jumped around from zero to about 2K ohms as I lightly placed my finger on the lever. Not a surprise, given the level of oxidation I observed on the trace - the wiper is sometime able to make good contact, but usually 'floats' over the trace on a layer of non-conducting oxidation.

None of my cleaners (DeOxit, Ether, alcohol) would remove the oxidation, so I (gasp!) used 1000 grit black oxide sandpaper to lightly sand away the oxidative layer, being careful to not sand down the resistive trace.  After a decent (but not extreme) sanding of the upper and lower contact traces, I re-tested the potentiometer and it appeared to work perfectly. Because of the way the wipers are situated, the upper connecting trace is never encountered, but I cleaned it anyway. I reassembled the potentiometer and re-soldered it to the board.

After reassembly, I retested the unit and it worked (almost) perfectly. Fader 1 worked perfectly with no 'strange' notes of CCs, but when I applied some pressure to the fader to the left or right, it still jumped around a bit, but worked completely normally if I just slid the knob up and down. I took pictures of the slide pot and jotted down all dimensions, but I didn't recognize the manufacturer (LSI or LS1?) - will still look for a suitable Bourns or Alps replacement and post here, if there's some interest. It's a 10K B103 if anyone can match the manufacturer with the potentiometer.

Happy to answer any questions. My goal is to find a replacement and swap out all sliders. This type of issue isn't limited to Arturia - I have a pricey DSI PolyEvolver where every single rotary encoder failed and had to be replaced. Designers trust manufacturers, and sometimes only the passing of time reveals these issues.

Hope this helps!

Edit: Think I found a matching part: Bourns PTA4543-2010CIB103 - available at Mouser; I'll order 10 and report back. The only downside is the lack of a dust cover, but I may be able to peel away the old cover and glue it to the new potentiometer. Also the lever may need to be modified slightly to mount the knob securely.
« Last Edit: January 06, 2022, 10:29:25 pm by amonti »

Koshdukai

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #1 on: January 07, 2022, 02:19:01 pm »
This is great info, thank you for sharing!

I have a similar issue with a KL mk1 (older gen) on Fader 9 and on Factory32's Fader 4.
I'm almost sure those have a similar cause, so when I get the time, I might do those same procedures on it.

Thanks!

MajorFubar

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #2 on: January 07, 2022, 03:13:40 pm »
Thanks for posting this.
Unfortunately disassembling the unit and repairing a faulty fader is beyond most people's skill-level, but this is great info for those who can.

It's a shame that these otherwise very well built machines often have hardware issues with their sliders, faders and keybeds, especially over time. It is indicative of what happens when your incredibly well-built machine is, at component level, assembled from poor-quality hardware made by an underpaid overworked Chinaman (actually more likely a woman) in a sweatshop.

Arturia aren't particularly to blame for this. It's just the unfortunate way of the world. Try building something like this keyboard, for the price Arturia make it for, using 100% components that aren't made in China. Take as long as you like.
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amonti

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #3 on: January 07, 2022, 07:11:01 pm »
I know what you mean re: disassembling the unit, but I've helped many otherwise "non-technical" people pick up a screwdriver and cheap soldering iron to repair electronics that they would otherwise throw away/recycle.  Opening the unit is straightforward, removing the slider/encoder board is simple - desoldering the sliders is a bit more challenging, but with some good snips and solder braid, shouldn't pose a huge challenge, and soldering is kind of fun and not overly difficult.

Regarding the components, completely agree with you on "poor-quality" hardware, although at that point it doesn't much matter if the unit is made in the US (like my PolyEvolver) or an overseas factory - selecting non-standard manufacturers for user interface components is always a risk based on cost analysis and (usually) planned obsolescence. Sometimes the risk pays off and components last for decades; other times, poor quality products drive people away due to poor performance and reviews.  Bourns has been making components for over 70 years, and although they are costlier, they will absolutely last for decades without issue. A "clone" manufacturer will generally use lower-quality materials and manufacturing processes to deliver the component at half the cost and (generally) sacrifice quality. Unfortunately, Arturia took a calculated risk on a cheaper manufacturer and it's causing a few problems - likely, the number of issues is minor compared to the overall number of units sold, but it's a shame for any of these units to be thrown away "before their time", plus Arturia is obviously a great company filled with smart people who want to deliver the best possible products.

I've ordered the siders and can definitely make an "unauthorized" repair guide of sorts when they arrive. Knowing what I now know about the slider, I could likely insert a narrow diamond grit pick into the slider slot to sand away the oxidation, but there's an equal chance of sanding away the carbon trace, which may make the issue even worse.

There also may be a firmware solution where the software ignores 'impossible' slider values by tightening up the hysteresis algorithms (e.g. sliders moving instantly from 0.8 ohms to 2K ohms - or whatever numerical values the A to D chips report), which seems to cause all kinds of other issues (the aforementioned random notes, unresponsive keys, etc.), although consistently addressing this across all units without introducing other weirdness may be impractical for all units and it's a burden to maintain separate firmware just for people with this issue. I guess you could also disable the control in MIDI control centre, but I don't like to disable functionality in this way, and I'm not sure it would even work.

MajorFubar

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #4 on: January 10, 2022, 07:59:06 am »
There also may be a firmware solution where the software ignores 'impossible' slider values by tightening up the hysteresis algorithms (e.g. sliders moving instantly from 0.8 ohms to 2K ohms - or whatever numerical values the A to D chips report), which seems to cause all kinds of other issues (the aforementioned random notes, unresponsive keys, etc.), although consistently addressing this across all units without introducing other weirdness may be impractical for all units and it's a burden to maintain separate firmware just for people with this issue.
Correct, and Arturia have done this in the past to solve a similar issue with 'jumpy' rotary controls.
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amonti

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #5 on: February 01, 2022, 04:11:59 am »
Edit: Think I found a matching part: Bourns PTA4543-2010CIB103 - available at Mouser; I'll order 10 and report back. The only downside is the lack of a dust cover, but I may be able to peel away the old cover and glue it to the new potentiometer. Also the lever may need to be modified slightly to mount the knob securely.

Ok, I ordered 10 Bourns PTA4543-2010CIB103 from Mouser and put together a guide of sorts; hope this is legible and help someone save their lovely controller from the landfill. Looks like there's a limit of five attachments per post, so I'll have to use a few posts to cover all images. Again, this is for the Keylab 61 MKII - other controllers may vary. Also, although I've repeated these steps twice without issue, there's a chance that you'll permanently damage your unit - I cannot assume any responsibility for any damage to your equipment or tools.

Before you start, you'll need: a clear work area, containers to hold caps and screws (~4), Philips screwdriver (PH-1 and PH-2), a pair of pliers, possibly a guitar pick, replacement slider(s) and soldering/desoldering tools.

For soldering/desoldering, you can use a gun or iron (at least 30W), leaded solder (60/40 SnPb), soldering flux (preferably no-clean), and your preferred desoldering tool: braid, bulb, or spring-loaded syringe (if you've never desoldered before, you may want to pick up a syringe). There are plenty of resources on the web to help you with desoldering; I'll point out the tricky steps with the slide pots.

For images 1-5:
1: Place the keyboard on a blanket or other protected surface - the tops of the black keys could be scratched if they aren't protected when the keyboard is flipped over. Remove all 9 encoder knobs and 9 slide knobs and place in a container (you'll need one slider knob to test fit later on).

2: Flip the keyboard over and remove all circled screws. Recommend PH-1 for the red-circled screws and PH-2 for blue-circled screws. Recommend using a manual screwdriver for removing and reinstalling all screws throughout this process. Although the screws are easy to identify (the red-circled screws are shorter, have a fine thread and screw into metal, while the blue-circled screws are longer, come to a point and screw into plastic - try not to over-tighten these when reinstalling), it's faster to place the screws into two separate containers with lids that close.

3: The bottom panel is prevented from rattling by thin foam tape at the back of the unit, but it's usually 'stuck' to the metal panel. You can slide a guitar pick just under the metal over and over the foam tape, then slid sideways to "unstick" the tape without damaging the finish.

4: Carefully pull the back down an inch or so; the keybed will remain attached to the back, but there are three connectors to disconnect. The first two are the aftertouch/pressure sensors on the top right-hand side. You may want to apply a dot of black marker to one to avoid mixing them up when reinstalling. The connectors pull out fairly easily with some wiggling - try to avoid pulling the connectors by the wires.

5: There's a far more sensitive flat cable to disconnect towards the middle of the back panel. Slide the keyboard down until just the connector is visible. Then use your fingernail or a plastic tool to pull down on both sides of the slide portion of the connector. These are highlighted in red circles. When they are fully down, the cable should practically fall out. Note that the blue reinforced portion of the cable faces away from you (important for reinstallation).

That's the first 5 out of 17 or so steps; will continue on separate posts...
« Last Edit: February 01, 2022, 06:02:11 pm by amonti »

amonti

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #6 on: February 01, 2022, 06:43:47 am »
That's the first 5 out of 17 or so steps; will continue on separate posts...

6: You can now slide the back panel towards the front of the controller being careful not to 'snag' the pressure and aftertouch connectors on the mod and pitch bend mechanisms. Again, the keybed will still be attached. Set the back and keybed aside. As per the image, wiggle the friction-fit flat cable off it's connector by pulling up and side-to-side. Next, remove all red-circled screws - the screws in the back are set slightly under the back case - use a long screwdriver and the cutouts in the case just above each screw to avoid stripping the screw heads. Store the screws in a container. Next, use pliers to loosen the standoff circled in blue and remove, but note that there's a small washer that protects the board under the standoff. Store the standoff and washer together as you'll need to washer to avoid damaging the board when replacing the standoff. The interface board will be 'free' at this point. I've also highlighted the solder points for each slider within the white rectangles. There are three points at the top: two for the housing, and one for the resistive element, and four points at the bottom: two for the housing, one for the resistive elements, and one for the wiper. You'll need to remove all solder from each of these points to replace the slide potentiometer.

7: Close-up of the standoff washer

8: Interface board flipped over

9: Close-up of the flat ribbon cable. You'll have to use more force than you think is necessary to remove the cable - it's best to handle the cable by the blue reinforced part.

10: Unfortunately, the levers on the replacement sliders need a slight sanding to remove some excess material. The portions of the lever in the red rectangles need to be sanded off, which isn't overly difficult, but it's easy to sand too much off and be left with a loose cap. The next post will cover sanding down and fitting the cap on the replacement lever.

amonti

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #7 on: February 01, 2022, 07:03:32 am »
The next post will cover sanding down and fitting the cap on the replacement lever.

11: To avoid debris entering the slide pot while sanding, cover the lever slot with tape, then use a few pieces of table just below the lever to keep it in place while sanding. Place a piece of fine sandpaper on the edge of a desk (350 grit+) and then sand the ridge off both sides of the lever, checking progress often. When you think you're close to sanding off the ridge, but while there's still a bit of plastic left, "round out" the top corners of the lever slightly and then test how a cap fits. It should be snug, but not tight. If it's too tight, then sand slightly more off both sides and re-check fit.

12: There are 'stops' on each side of the lever that should mate with the underside of the cap (red circles in the image). If they don't touch, round down the corners of the lever, as the cap is very slightly tapered. When the fit is perfect, the cap should be snug.

13: Since the new slide pots don't come with a dust shield, I slid a hobby knife under the dust cover to remove it, setting it aside for mounting later. The cover is very fragile and rips easily, but it should be able to remove it whole.

14:  Working on the back of the control board, identify the four lower solder point on slide pot you are replacing. Heat up your gun and while you're waiting, apply flux to each of the solder points.

15: When your gun is sufficiently hot, flow some solder on the tip of the gun/iron and then heat up each solder point until the lead-free solder melts, then add some leaded solder. The leaded solder has a much lower melting point than lead-free solder and is much easier to remove as it stays molten for slightly longer. Mixing even a little leaded solder lowers the melting point of the lead-free solder amalgam.

That's it for the 'easy' part - now comes the most difficult bit - desoldering.

amonti

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #8 on: February 01, 2022, 07:27:04 am »
That's it for the 'easy' part - now comes the most difficult bit - desoldering.

16: I don't have detailed images of desoldering the slide pots as each desoldering tool has a different technique. The basic idea with vacuum pumps (bulb or spring-loaded syringe), is to heat each of the 7 points until the solder flows (and even for longer to really heat the component up), and keep the solder liquid long enough to "suck" it up into the tool. While this is relatively easy for the potentiometer resistive element and wiper terminals (there are 3), it's far more difficult to remove solder from the housing solder points, as the shell itself radiates heat away from the solder, which cools it faster. All I can suggest is using a very hot iron and making sure you're quick enough between melting the solder and using the bulb. Once you've removed all the solder from the pins and 90% of the solder from the housing points, you can likely gently pull on the slide pot as you're heating up the housing points. In this way, you can slowly 'walk' the slide pot off the board. You should eventually be left with 'clean' pins as per the picture. Remove the old slide pot and insert the new slide pot (there's only one way all the pins line-up). You may have to use some desoldering braid to remove excess solder around the holes to fit the new slide pot. Once you've fit the new slide pot, flux and solder all 7 joints.

17: If you can, clean excess flux off the board with appropriate cleaner (usually isopropyl alcohol), then flip the board over and re-apply the dust shield, ensuring the entire cover is is 'pinched' towards the middle to keep dust out. The cover should look similar to the other sliders.

Reassembly is the reverse of the removal, but here are a few tips:
- Remember the washer under the standoff
- Ensure the flat cables are inserted all the way into their connectors, and ensure the keybed cable is 'locked' by pressing up on the connector.
- Remember to re-insert the aftertouch and pressure connectors
- When putting the back cover back on, start with the screws in the middle over the standoffs - make sure they line-up and leave the screws slightly loose until all other screws are in-place - if the standoff screws don't line-up, move the case slightly - try not to insert anything into the standoff as the threads in the standoff could be damaged
- Slowly turn all screws until you're sure they are going in  straight - no screw in this assembly should be overly difficult to screw in
- Mind the flat cables - try not to bend or pinch the keybed cable
- The encoder knobs have a flat spot that lines up with the flat spot on the encoder shaft

Once the unit is back together and knobs are all snug, give the unit a thorough test. In my case, the replacement worked perfectly and no faulty readings were thrown - regardless of how I manipulated the slider knob.

Good luck, and please post any questions and/or success stories.



« Last Edit: February 01, 2022, 06:01:30 pm by amonti »

MajorFubar

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #9 on: February 01, 2022, 08:41:16 am »
Stunning level of detail and insight, thank you for sharing.
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popoblito

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #10 on: February 05, 2022, 10:45:37 am »
hey there, thank you so much for making this post, I have a very similar issue with the first fader, which sometimes sends random inputs regardless of its position, plus I also see that the keyboard sends continuous midi signals to my DAW (Cubase) even when I'm not touching anything, so I think it's the same problem you were having, more or less (because I tried contacting support a couple times, they were really good but didn't help me solve the issue on a software level, so I guess it's some kind of faulty hardware).
I even made a post about it here on the forum btw

Now, afaik my keylab is still under warranty and I wouldn't like to open it up and repair it myself since I'm no expert at all, so I could just ask for a new unit right?


amonti

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #11 on: February 06, 2022, 03:15:39 am »
hey there, thank you so much for making this post, I have a very similar issue with the first fader, which sometimes sends random inputs regardless of its position, plus I also see that the keyboard sends continuous midi signals to my DAW (Cubase) even when I'm not touching anything, so I think it's the same problem you were having, more or less (because I tried contacting support a couple times, they were really good but didn't help me solve the issue on a software level, so I guess it's some kind of faulty hardware).
I even made a post about it here on the forum btw

Now, afaik my keylab is still under warranty and I wouldn't like to open it up and repair it myself since I'm no expert at all, so I could just ask for a new unit right?

Sounds suspicious, but there's usually a few "spots" on the faulty fader that you can find where the random signals stop. For me, if I set the first fader to somewhere in the middle of its travel, the controller worked as normal, but as soon as I dragged the fader down, the messages started and didn't stop - even if I stopped manipulating the fader (for the reasons in this post). See if you can find a fader position where the signals stop (maybe at the top of the fader travel), which would indicate to me that it's a similar issue, although I wouldn't be overly surprised if the entire travel of your fader was oxidized based on what I saw. Not that you should have to do this if the unit is under warranty, but you could purchase an air duster and try gently blowing out any dust that may have settled on the potentiometer wiper. Unlikely, but worth a shot if it's under warranty, and I wouldn't recommend using fader cleaners or lubricants unless Arturia directed you to.

Regardless, sounds like Arturia should take care of you under warranty - please let the board know how it turns out.

Horisonten

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #12 on: June 10, 2022, 11:56:02 am »
Wow, exactly the thread I was hoping for. Thank you so much for spending time documenting the process for the rest of us. I'm out of warranty and will be forced to do this procedure on my first fader.
« Last Edit: June 25, 2022, 11:04:26 am by Horisonten »

Horisonten

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #13 on: June 10, 2022, 01:27:42 pm »
Also why is this thread not in the main Keylab Mk2 technical sub forum instead of Legacy Hardware? This is still a very current problem and I had a hard time finding this thread. Perhaps it is intentional so that as few as possible knows about the existence of these issues?
« Last Edit: June 25, 2022, 10:58:15 am by Horisonten »

Horisonten

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Re: KeyLab MKII "Random" Sliders - solved
« Reply #14 on: June 25, 2022, 11:03:33 am »
Just finished replacing one of the sliders. All went smoothly thanks to this thread! I would have never guessed why the back wouldn't come off if it wasn't for step 3 (guitar pick trick). The only hard part of all the steps is the desoldering of the old slider.

 

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