[sdiy] ENSONIQ MIRAGE DSK service notes manual

[Graham Atkins]

There were a number of threads about keyboards recently that you may  
be able
to search. Recently there was a thread about arpeggiators that  
included a lot of
info re keyboard scanning. There was also a thread re keyboard  
problems on a
Korg Polysix in November.

I would always go for the lowest common denominator here. Unless  
something
drastic has happened forget the diodes for a moment. Check the  
connecting
cables and connectors for possible continuity errors or poor  
connection on the
pins. There may be a multiplex IC that has failed. Also I would  
suspect the
keyboard contacts. This (And the connectors) could be a problem if the  
unit
has been kept in a damp atmosphere. Off the top of my head, Bob Weigel  
may
be the man to talk to.

Graham

On 21 Jan 2009, at 18:50, Nathan M. Reeves wrote:

> Excellent idea Graham!
>
> The unit works perfect through MIDI!
>
> I hooked up my other Mirage to the MIDI IN and was able to trigger  
> the standard "this is a blank formatted diskette" sample that comes  
> on the format diskette 8^)
>
> so, its the keyboard with its associated circuitry....
>
> i remember someone posting a thread about how to test a keyboards  
> diodes though i hardly think they all went out at the same time but  
> i would like to check this first...
>
> how do you check a keyboards diode matrix?  i have a diode icon on  
> my radiowack DMM but haven't used it....
>
> assuming the diodes all check out ok, any other ideas on what to  
> check?  the keyboard matrix connects to the main board via the 24  
> pin (its actually 26 pins but  pins 25 and 26 are not connected) J3  
> connector and this goes to U6, which i am not sure of its function...
>
> i am gonna reseat all ICs that allow this....and might as well check  
> all the voltages...
>
> can someone explain to me what happens next after the j3 connector?
>
> how would you "go down the line" for isolating what is not working  
> properly?
>
> cheers
>
> nate