Vintage Synth Repair

- Is the problem present also when you control instrument thru MIDI?

- First I would check and clean key rubber contacts, diodes in key  
assembly, connectors.

- If this will not help, it's time to check IC45 - key decoder, IC46 -  
buffer and other components between the keyboard and CPU.

Daniel Forro


On 17 Jan, 2014, at 10:30 AM, <mpigott2@...>  
<mpigott2@...> wrote:

>
>
> I went to play my JX-3P and noticed certain notes not in a row are  
> not sounding.
> Didn't have a piece of paper but they were in the lower registers.
> None were in a row.  It was like E not sounding then C, etc.
>
> Put it in test mode and all oscillators are cycling through, but  
> these same notes are not sounding. Isn't there an IC that  
> distributes or scans the keyboard and this is at fault?
>
> Any ideas?