HI Ed, thanks for your reply.
The voice chips are Yamaha YM2203c.
https://en.wikipedia.org/wiki/Yamaha_YM2203here's a datasheet:
http://www.alldatasheet.com/datasheet-pdf/pdf/90458/ETC/YM2203.htmlDid you manage to measure the outputs from the power supply?
thanks!
Christian.
--- In Simmons_Drums@yahoogroups.com, "Ed" <edrose1@...> wrote:
>
> +1 on this. I fired mine up to try and help and voices 1-3 are dead. A schematic and source for the Yamaha voice chip would be great.
> Thanks in advance!
> Ed
>
> --- In Simmons_Drums@yahoogroups.com, "xjnx0x" <concken@> wrote:
> >
> > Hi, I'm new here...
> >
> > I joined to see if anyone has schematics or experience fixing the Simmons SDE. Mine stopped working around 1998 and I'm trying to get it back up and running because I miss it.
> >
> > The power supply went out when the caps blew. I've replaced these and the unit now turns on again, lights up, responds to buttons and knobs, even responds to midi. Everything seems to work from the front panel, but there is no sound, except for a harsh intermittent buzzing for a few minutes after its turned on.
> >
> > I measured the voltage going to the yamaha chips and found it to be lower than their datasheet says is acceptable. Datasheet says minimum 4.8v and its measuring 4.5v. I suspect the power supply still has issues and I think fixing and verifying that is the best place to start.
> >
> > Anybody have schematics? Tips for troubleshooting? Anybody else fixed one of these? If a schematic for this machine isn't available, maybe a schematic from one of its contemporaries would have the same power supply design.
> >
> > Failing that, could I talk somebody into opening their healthy SDE up and measuring the voltages on the power supply ribbon cable so I can at least tell what those voltages are supposed to be?
> >
> > thanks for your help.
> >
>