Old synth & variac, wasRe: FGTH, was Re: [sdiy] "Foot pedal"?!

[rkmoore at memphis.edu]

Hi John,

I don't think I would run it up on a variac.  If it really hasn't been 
powered on in 20 years, I might disconnect everyhing from the power 
supply and power it up at no load first.  After checking for proper 
voltages and ripple I would power it down, connect everything again, 
and power on a second time.  This may not be the right techniques 
either, though.

Richard Moore

----- Original Message -----
From: "Paul Perry" <pfperry at melbpc.org.au>
Date: Monday, May 16, 2005 10:30 am
Subject: Old synth & variac, wasRe: FGTH, was Re: [sdiy] "Foot pedal"?!

> 
> ----- Original Message ----- 
> From: "john mahoney"
> > Should a keyboard that's been asleep for 2 decades be brought 
> back up with
> a
> > variac?
> > --
> I would think not, because the rectifiers & main caps are driving
> regulators, and
> the system as a whole isn't designed to run with an odd input.
> In fact, with the input under-run, you will be sending odd unsmoothed
> voltages to various parts,
> with possible problems with analog and digital circuit interactions
> (sometimes stuff is designed
> in such a way that it needs some power rails to be always higher than
> another, or to reach
> operting voltage in a particular order).
> 
> I hope that someone with more experience than I have will answer 
> as well,
> but personally
> I don't think it is ever a good idea to run anything outside its 
> designspecs, even on the low
> side.
> 
> paul perry (Frostwave analog fx) Melbourne Australia
> 
>