EPS/ASR Keyboard Calibration Problems

Question: My EPS sometimes fails to tune the keyboard sometimes.. At times it works perfectly. Maybe for a day, then another day I can't get it running.. It actually helps if I hit it a few times.

Answer: When I had this problem, it was the connector between the cable for the keyboard and the main unit board--there was an Ensoniq technical bulletin on this problem as it was apparently common. My local repair place simply hard-wired (soldered) the cable, and since it was a factory defect they did it for free, although I suspect that the Classic is now so old they won't honor this any more. The fact that it works if you whap it makes me suspect that this is the problem. If you get inside the unit and clean the connector with alcohol and seat it nice and tight, I bet this will help.

Another similar problem is that the keyboard assembly is made up of actually two circuit boards, which are connected together with a very cheap connector. Activating aftertouch on a key causes these boards to flex ever so slightly, and over time, causes this connector to wear and send false information to the mainboard. The solution is the same though-replace the connector with a ribbon cable soldered across the two boards, and the problem should disappear. I had this happen with my EPS Classic, and my friend fixed it for me and it has worked ever since (I have since upgraded to a 16+ and sold the Classic to my friend [who is on this mailing list still I think], and he hasn't experienced any more problems with this either). Common symptoms of this connector being at fault are:

Let's start off with the standard warnings/disclaimer. This fixing procedure applies for the EPS Classic; however, I did have one person report he fixed his 16+ using this procedure, and opening my unit up reveals a similar setup, so it will also work with a 16+. I have never had the chance to open up an ASR, let alone even see or play one, so I'm not sure if this will work for the ASR as well. I am also in no way responsible should your EPS blow up or something weird happen, and please make sure you read the entire procedure before starting.

First, let's separate the keyboard module from the rest of the sampler. To do this, remove the four screws located on the top corners of the sampler's display section. This will allow the top panel to be swung open towards the back (it takes a bit of force to pry up the cover the first little bit). Now, close the front panel back up, turn the sampler upside down, and remove all of the screws you can see underneath. These screws are what holds the keyboard assembly to the rest of the sampler (from now on, I'll use the term "sampler" to refer to the entire unit, and the word "keyboard" to refer to just that one part of the sampler). Two of these screws also hold the floppy drive/pitch wheel/mod wheel assembly in place, which must be moved to allow the keyboard to be removed from the sampler. A total of four screws hold the floppy/pitch/mod assembly, with the other two being on the back panel-remove these too. Once all screws are removed, turn the keyboard carefully back right side up and open the top panel. Next, carefully pick up the floppy/pitch/mod assembly and move it to the side (it's attached with many wires that are soldered to the rest of the sampler, but you should be able to pick it up and turn it enough to allow the keyboard to be removed). After unplugging the bus cable that connects the keyboard assembly to the motherboard, you should now be able to lift the keyboard assembly out from the rest of the sampler. Set the rest of the sampler aside for now, as it is the keyboard assembly we'll be working with.

The first thing you'll see underneath the keyboard assembly is a sub-assembly where the ribbon cable you unplugged was attached to. This board has a similar type of connector like the faulty one separating the two halves of the main keyboard circuit board. This connector doesn't usually cause problems, as there is little or no movement here, but while you're at it you might want to remove the screws holding it to the rest of the assembly and clean the connector. The connector at fault is underneath all of the keys, so we'll have to remove them to get access to it. Start off by removing all of the springs from the back of the assembly by using a pair of needle nose pliers, grasping the top of each spring, and lifting it up and out of its holder (it's a good idea to put them all in a cup or something so that you don't lose them-and don't worry, they are all the same). Next, remove each key by grasping the front of it and pulling it towards you and at the same time applying a light upward force to pop it out of the holder. It's tricky at first, but you'll get the hang of it after the first few. I find it's easiest to start at the bottom of the scale and work your way up when removing keys. Also, don't worry about mixing them up-they are all labeled according to their position in the octave, and all of the black keys are the same.

Once all of the keys have been removed, you will see the main keyboard circuit boards, with a brown colored connector joining the two halves-THIS IS YOUR PROBLEM CAUSER! You'll next want to remove the two halves of the board off of the plastic assembly that holds them together so that you can separate them. To do this, you must remove all of the small plastic ties that hold them down (squeeze the two halves of the tie together and push it through each hole-they are a real pain to get out). Once they are all out, you can remove the boards off of the plastic assembly and separate them at the connector. Take a look at the male half of the connector-I'll almost guarantee you that you'll be able to visually see where the wear has been occurring. You now have three choices:

My personal favorite is option #3, because hopefully, if you do solder wires directly across these two boards, you will never have to separate them again (you can still remove them out of the keyboard though), plus it will eliminate any future wear problems. I have done this to my Classic EPS and have never had any keyboard related problems since. Another thing to check for before you separate the two boards is the actual solder joints of the connector itself. On mine, doing continuity checks across each pin pair of the connector revealed some pairs with resistance in them! Resoldering the connector and the resistance disappeared (this was before I decided to replace the connector-it helped but didn't fully solve the problems I was having).

While you've got everything apart, it's a good idea to give everything a good cleaning with a can of compressed air or a non lubricant contact cleaner SAFE FOR PLASTIC.

Re-assembly is basically the reverse of removal, noting once again that the keys are all labeled, and black keys and springs are all the same. Don't forget to plug back in the ribbon cable between keyboard assembly and motherboard. Then cross your fingers, plug your sampler back in, power it up and hopefully it will calibrate and all of your problems will be solved! If it still will not calibrate, other places to check are the sub-assembly board's connector or the ribbon cable between this board and the sampler's motherboard, but hopefully you won't have to worry about that.

Many thanks to Ric Miller for his original fix procedure that helped me get my EPS calibrating again, as well as my friend Tim Rosenquist for performing the actual operation.

Contributed by: Todd Aiken

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