[sdiy] TR-909 reset pin on PSU

[Colin f]

This pin holds the 909 CPU in reset until the power supply is stable after
power-on, and resets it again as the power goes off, or there is a supply
brown-out.
It's there to stop the 909 writing spurious data into its battery backed
storage.
There are various CPU reset control chips you could get that would do the
same job for any given PSU.

Cheers,
Colin f

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of epk
> Sent: 10 July 2009 00:12
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] TR-909 reset pin on PSU
> 
> Hey all,
> 
> I've got a TR-909 that I'm migrating to a custom case/panel and  
> external PSU.  The 909 has a reset pin on the PSU board that goes to  
> the switch board which is throwing me for a loop.  I don't really  
> understand what happens with this pin, and more importantly how to  
> spoof the functionality with an external PSU that doesn't have a  
> reset.  Is there an easy way to do this?
> 
> Here's a pic of the PSU board schematic:
> 
> http://i72.photobucket.com/albums/i182/wholetone/909%20psu%20board/ 
> Picture2.png
> 
> tx,
> 
> epk
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy