KennaOkoye wrote:Thanks a lot guys the symptons I am reading aboout doesn't sound like a chip problem.
True. A scanning chip problem would affect the same notes in every octave.
The bad news is, rhino is correct. I've never worked on a Roland synth that uses rubber contacts that didn't require complete disassembly, at least in the affected area. Most scanning keyboards have contacts that come in sets of 6, with a set of 7 on one end, so if you want to work on just one key, you're going to be taking at least 6 keys completely off the keyboard. If you're lucky, both bad keys will be on the same strip. In facts, odd of that are good, because I bet you a dollar they are both within an octave of middle C.
Quickest fix: Take the contact strip that is causing trouble and swap it with an identical one from either the very top or the very bottom of the keyboard, especially if you never play up (or down) there, as those contacts take the least abuse (Hint: That's why I made the bet that your bad keys are in the middle of the keyboard).
Not-so-quickest fix: The key contacts need to be "leveled". The cause of 90% of key triggering problems are the fact that the repeated striking of the contact against the circuit board wears away the contact where it meets the two conductive areas on the circuit board, until the point that the pattern of the circuit board becomes imprinted into the contact. If that doesn't make sense (it is kind of late as I'm typing this, insomnia strikes again), simply look at the bottom of a worn contact, and you will see a mirror image of the area of the circuit board it touches. The problem when it gets that way is the non-worn area gets tall enough to keep the contact from being able to bridge across the two conductive traces on the circuit board, unless you press the key REALLY hard. So, leveling the contact means to burnish it with a good-quality rubber eraser (NOT the kind with an abrasive imbedded in) until the surface of the contact is once again flat and no longer shows the mirror image of the circuit board. The contact itself (the little black cylinder) is also made of rubber, a kind that conducts electricity, so leveling the contact is a bit tricky since it is constantly flexing as you try to rub the eraser against it. Be patient and go slow. Luckily the contact strip is a bit sturdier than it looks, so go ahead and make sure you have a good grip on the contact. The contact surface MUST be parallel to the circuit board when finished, and not slanted at an angle. Under NO circumstances should you use a solvent to clean the rubber contact strip, ESPECIALLY do not use alcohol (unless applied internally after the job is completed
). If the contact strip shows any tears as rhino described, replace it, period.
Better fix: All the key contacts will behave this way eventually, so do them all while you're at it. C'mon, it's only 176 contacts to level!
Seriously, it's better to get it over with all at once, since you will not feel like taking the sucker apart again should another contact go bad a week later.
Best fix: If you can find all new contact bubble strips, replace them all and you won't have to worry about it again for another 20 years. No, it's not cheap (assuming you can even find the parts). However, when someone brings a keyboard to me and wants all the contacts fixed, it is in fact MUCH cheaper for labor to go ahead and swap the contacts vs. polishing all 176 of the little beasts.
HINTS: If you do choose to take the keyboard apart, if the D50's keyboard in anyway resembles any of the Juno or JX-3P keyboards, don't lose the little adhesive strip of plastic that prevents the keys from sliding out of the frame, and avoid removing/replacing the key springs in a thickly carpeted area (Please do NOT ask me how I know this
). Also, remove the end of the spring from the KEY first, then from the frame, and replace the end of the spring in the FRAME first when reassembling (again, please do not ask me how I know this
Good luck! The process is not as bad as it sounds, it's just tedious and requires careful attention!