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Akai MPK88 Velocity Problem - Help
Old 4th October 2013
  #1
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Akai MPK88 Velocity Problem - Help

Good day everybody.

I own an Akai MPK88 midi controller. Three keys have problems hitting full velocity. These particularly keys do not register full velocity, except very infrequently when slammed with extremely excessive force. I actually brought it to a repair shop. Paid to have them fix it. They checked it. Told me that they could not find a problem with it. I've got it back home and the problem is still there. So I'm out my money and I still have a malfunctioning piece of gear. Very frustrated as you can imagine when trying to play dynamic piano parts. It's just not happening as it should.

I'll also mention, I'm using it via USB and controlling software and hardware through my PC running Vista.

My question is. What could the problem be? I figure maybe just dirty contacts?

Should I bring this back and have the repair shop clean it? I'll happily pay for the service. I just want a working keyboard.

Or should I just do this myself??

Thank you for your help!

Frank
Old 4th October 2013
  #2
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Richard Crowley's Avatar
 

It is not clear from your description whether the problem actually disappeared while at the repair shop, or whether they just "could not find" the problem? That may be a clue that is worth more careful scrutiny. My first guess would also be dirty contacts.
Old 4th October 2013
  #3
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Thanks for the reply Richard.

I'm not certain how they tested it, or with what. Maybe it just 'worked' while there. I guess I'll never know....

I've decided to take it upon myself and attempt to clean the contacts.

I've got 'er open on the kitchen table. Just about to start removing the keys. Unfortunately there is no service manual that I can find for this. So fingers crossed and winging it.

Side question. In the metal housing for the keys, there seems to be some kind of grease between where the metal pieces connect with each other. What's the reason for that out of curiosity?
Old 4th October 2013
  #4
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Richard Crowley's Avatar
 

Without looking at it first-hand, I wouldn't guess what the grease is for. Are you saying it is between the pieces of the metal housing? Or on the contacts?
Old 4th October 2013
  #5
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Richard,

The grease is between the pieces of the metal housing.

thanks
Old 4th October 2013
  #6
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Richard Crowley's Avatar
 

I suppose it is possible it might be conductive grease to ensure connection between the housing pieces for better shielding or something. Conductive grease like that on the key contacts would possibly produce the symptoms you are describing.
Old 4th October 2013
  #7
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Thanks Richard

So, I ended up taking the thing apart and cleaning the contacts on the circuit board with rubbing alcohol. I think I've found the exact problem.

In order to clean the board, I had to remove the rubber buttons. There were four strips in all on the first contact circuit board. I suppose when I put the rubber strips back, I had done so in a different order, because now my original velocity problem has picked up and moved down an octave!

So, is it a case of the conductive coating on the rubber buttons wearing off? I did not hit them with the rubbing alcohol because I didn't want to strip them of their coating. I figure I can call Akai and get a set of replacements?

thoughts?

frank
Old 4th October 2013
  #8
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Richard Crowley's Avatar
 

Someone sells a coating that you can "paint on" the conductive surface of rubber buttons. But I am VERY surprised that any keyboard, especially a velocity-sensitive variety uses that kind of button.

It is possible that it is deriving some sort of analog key-press profile from variable resistance. In which case trying to fix it by restoring the conductive surface would just make it worse. You would need an exact replacement from Akai.
Old 4th October 2013
  #9
Gear Guru
 
Muser's Avatar
it could just be that Akai have a velocity scale curve applied as standard.
those can make quite different response characteristics. it's usually better if manufacturers always (at least) make a selectable linear velocity curve available.

some info in the later parts of this thread on a kontakt script for looking at velocity of keybeds.


A good 88 full weighted key MIDI controller, with many velocity levels and USB?
Old 4th October 2013
  #10
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Richard Crowley's Avatar
 

Frank has proved pretty conclusively that it is a hardware problem with the rubber button contact strips. Whether it is repairable while maintaining the functionality is an open question.
Old 4th October 2013
  #11
Old 4th October 2013
  #12
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but I would try to get new button. you have to be pretty neat when applying the chemical.
Old 5th October 2013
  #13
Gear Guru
 
Muser's Avatar
if you get a replacement pad set and also get some keypad fix, you can replace with a new set and then fix the old set at your leisure. I fixed my own on a CME. a nice artist brush some cotton buds, alcohol and a 10X jewelers magnifier does the trick.
Old 6th October 2013
  #14
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Thanks for the replies fellas!

I am going to contact Akai tonight and request a new set of pads. depending on the turnaround time, I might swap out the faulty buttons with the top octave for a temporary 'fix.' never play those high notes anyways lol

Let's see how well Akai performs with customer service.

frank
Old 4 weeks ago
  #15
Gear Head
Thanks for this description. I have the same problems with my mpk88. Two keys require heavy whack to get up to 127. Did you manage to fix yours? Frankthefunky1?
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