Vintage Synth Repair

I have a Kurzweil SP88x that the display has started blinking. If I hit a key when the display is off it will not play but it will start to sound as soon as the display comes back on while still holding down the key. These cycles are short, so when I play the sound come and goes with the cycle on the display.

I switched out the wall wart but that did not remedy the problem. I am a player not a tech but, if possible, I would like to fix this myself. I have had the case open and removed the keyboard before so if it is just a matter of replcing a component I think I can do that. I would not attempt to take a soldering iron to a PC board.

Has anyone here seen this before?

Thanks,
Dan

Hi Dan.
This sounds like the main smoothing capacitor(s) which can sometimes fail (dry out).  What you describe sounds like the voltage builds up to the point where the electronics can work. As soon as this happens, the working electronics drags the voltage back down again and the cycle repeats itself. (in the old days we used to call this motorboating).  Look where the supply comes into the circuit board and look for any (electolytic)capacitors in that area. If you don't fancy the job yourself, take it to a TV tech and show him this note, he will know what to do.  Perhaps you could take a photo of the board and put in the photos section.
Good luck. Let us know how you get on.
John. 

--- In vintagesynthrepair@yahoogroups.com, "n8398r" <dan-kelly@...> wrote:

>
> I have a Kurzweil SP88x that the display has started blinking. If I hit a key when the display is off it will not play but it will start to sound as soon as the display comes back on while still holding down the key. These cycles are short, so when I play the sound come and goes with the cycle on the display.
> 
> Has anyone here seen this before?
> 
> Thanks,
> Dan
>

Hi john,
I have not gotten around to taking the keyboard apart but blinking has stopped. If it starts up again I will open it up and take some pictures.

Thanks,
Dan

--- In vintagesynthrepair@yahoogroups.com, "john" <john@...> wrote:

>
> Hi Dan.
> This sounds like the main smoothing capacitor(s) which can sometimes fail (dry out).  What you describe sounds like the voltage builds up to the point where the electronics can work. As soon as this happens, the working electronics drags the voltage back down again and the cycle repeats itself. (in the old days we used to call this motorboating).  Look where the supply comes into the circuit board and look for any (electolytic)capacitors in that area. If you don't fancy the job yourself, take it to a TV tech and show him this note, he will know what to do.  Perhaps you could take a photo of the board and put in the photos section.
> Good luck. Let us know how you get on.
> John. 
>