The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Synths for sale  Search Gearslutz Go Advanced
Alpha Juno keyboard fix (intermit contacts)
Old 6 days ago
  #1
Jose Ramón Alvarado Villa
 
Don Solaris's Avatar
Alpha Juno keyboard fix (intermit contacts)

This is a common problem with Alpha Junos...


Step 1 take the Alpha Juno out of the studio.



Using screwdriver remove all the screws from the side of the unit and from the bottom of the unit, with exception to the brassy ones below the keyboard. Don't remove those yet.



Open up the hood and make sure to remove the three screws on this board in the centre. Now lift the unit again, and remove those brassy screws that hold the keyboard. Use your other hand to HOLD THE KEYBOARD STEADY else it will fall. The keyboard itself has two notches which actually hold this board shown above. This is why you have to remove these three screws, to pop up the PCB board a little bit, then remove the keyboard. You will do the same procedure when assembling the unit, except you will do it in reverse.



Now gently lift the keyboard and if you have a phone nearby, snap a photo, although you should see a very similar picture. The point is to know which of the two sets of wires goes into which connector. In my case, the yellow green one goes into top connector. If your Juno has different coloured wires, please snap a photo because both connectors have the same number of pins.



Alpha Juno should now look like this.



Place the keyboard on a safe spot and start removing metal springs that hold each key in place. You do that by placing the screwdriver below the spring and simply by applying a lever action to pull it out of the metal anchor that is on top. Use other hand to ensure the spring doesn't fly away by holding it with a thumb. IMPORTANT(!) You must either wear eye protection or close your both eyes when pulling each spring. Please take that as a SERIOUS WARNING and not some nanny state advice!!! And here's a small tip: when removing keys, you can leave springs on them. That way you don't have to separately remove the springs and then place them back.



You remove the key by pressing its upper part down and simply pulling it out. Hint: you first remove two adjacent white keys, and then the black key. It doesn't go the other way.



If the keyboard mount has a plastic strip on this place, you will have to gently push that strip with a screwdriver in order to ease up the pressure it applying against the key pins when you try to pull out the key. In other words, the key won't go out because of this plastic strip. But since it is flexible, you can simply push it with a screwdriver to make some room, to be able to pull out the key.



You will need a marker in order to mark every rubber stip before you pull it out. What you want to do i to place a small red dot on the lower part of the strip, before you pull it out. That way you will know the correct orientation of the strips when you will be placing them back. This is an IMPORTANT step, because strip placed upside down will have incorrect velocity reading.
Old 6 days ago
  #2
Jose Ramón Alvarado Villa
 
Don Solaris's Avatar

After you remove all of the rubber strips, it is time to clear the PCB contacts first. You will start by using cotton and highest percentage alcohol you can buy, ideally 99%, aka denaturalised alcohol. You will clean the contacts area of where the rubber contacts once were.



You will use another cotton and repeat the procedure. It should not look dirty as it does on the picture above. If it does, repeat again. The contacts area must be clean.



Now comes the most important part of the cleaning. You need to dip a cue tip into the alcohol and clean each one of those little black contact until you remove all of the dirt that was on them. If you do not remove even the smallest piece of dirt, the key will not work right because of the flat surface of the contact.



The result should be completely black contacts.



Placing springs back is very easy with a help of a small screwdriver. First you attach the spring to a key. Then you place the screwdriver into the loop of the spring and apply a small action to extend it until it reaches the anchor onto which you fix it. And that's it.



Return the unit in the studio, and have fun.
Old 6 days ago
  #3
Here for the gear
 

Thanks for the detailed write-up! Can you describe the symptom this addresses a bit more? By intermittent contacts you mean some key presses do not result in a note-on? Does the issue potentially affect Alpha Juno 1 as well?

I have a Alpha Juno 1 and recently replaced a key which was broken, learned by trial about the plastic strip covering the keys. It was difficult and I thought I would break it by prying it up but it turned out fine. Seeing the issues with Alpha Juno 2 almost makes me thankful the 1 doesn't implement velocity or aftertouch!
Old 6 days ago
  #4
Jose Ramón Alvarado Villa
 
Don Solaris's Avatar
So far every Alpha Juno i've encountered had this problem of some keys not triggering or needing extra push, or having poor velocity reponse. To make things worst, the problem can come back on a cleaned up unit after 10 years or so. I guess you have a clean and tidy studio. Or just a good specimen.
Old 6 days ago
  #5
Here for the gear
 

Far from a good specimen in many ways but I will consider myself lucky that all the keys work perfectly!
Old 6 days ago
  #6
Gear Maniac
 
CathodeRay's Avatar
Great write up Don. If i may add in addition to the issues you mentioned i have come across an issue with the key beds on these where several keys in an octave wouldn't trigger and after much hair pulling i discovered a broken trace on the contact strip board that needed to be jumpered a lil time consuming to find the trace but with a multi meter do a continuity test on each trace in the affected region and you will pinpoint it. Miss my Juno 2 :(
Old 5 days ago
  #7
Lives for gear
 
Synthbuilder's Avatar
Excellent write up Don.

Can I just add that the springs for the black keys and white keys are different. One is longer than the other - so either keep each spring with the key they come with, or place the springs in two separate piles.

The other thing I do is use a metre ruler to weigh down and hold all the felt 'fingers' away from the contact board when I'm cleaning the contacts. Otherwise they tend to get in the way when cleaning.

In some cases I have had to also vacuum up excessive dust and hair from the keyboard mechanism surfaces before cleaning with IPA.
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump