Emax

i agree i recon its a diode or the return circuit to the scanner cpu

the scanner cpu gets pulse signals from when a key is pressed0volts to 5volts to zero volts like a half square wave cycle

he says he is getting voltage across the diode 5v when key is pressed

so to me the keys is making a circuit as tested but that siganl is not getting back to the cpu scanner

now its either the wire for that octave is damaged or there is a broken track 

he needs to trace the tracks from that octave and see if he is getting continuity to the header cable if he is then its at the mother board end 

as the scanner cpu is not recieving the trigger pulses for that octave
  ----- Original Message ----- 
  From: emax_dx5 
  To: emax@yahoogroups.com 
  Sent: Monday, July 09, 2012 6:09 PM
  Subject: [emax] Re: Five top keys fault


    

  Yeah I don't discard it at all, but three 1125's I had to deal with were completely dead when failing. Talking about a failing octave (just that) I would go for traces or diodes (appart from all suggested above). Those keyb pcbs are prone to crack traces . 

  --- In emax@yahoogroups.com, "jammie" <jammie.emma@...> wrote:
  >
  > actually i can be the scanner chip iv had it when you can play notes on kewyboard but when pressing buttons its arratic and jumps allover the place
  > ----- Original Message ----- 
  > From: emax_dx5 
  > To: emax@yahoogroups.com 
  > Sent: Monday, July 09, 2012 2:59 PM
  > Subject: [emax] Re: Five top keys fault
  > 
  > 
  > 
  > I won't go for the MPU Scanner (IM386). When it fails, no button or key usually work.
  > 
  > You said you sent midi to the Emax and it made sound. Did you check the MIDI OUT commands the emax is sending? you can do it both with a Midi analyzer on your computer or using the function MIDI Scope. Check if it sends Key ON and OFF commands or not. If any of those cases:
  > 
  > Go to the keyboard Printed Circuit Board. ONce you already checked diodes, Check continuity on the traces involved with those keys (a multimeter will do the job). If a common ground trace is open, this fault uses to happen.
  > 
  > hope it helps.
  > 
  > Best.
  > Jose
  > 
  > 
  > 
  > 
  > 
  > [Non-text portions of this message have been removed]
  >



  

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