Power supply question (-3 VS +3)
 

bart bervoets wrote:

I want to replace a busted switching power supply by another type i have on
the shelf, but there's
no -3V on the replacement.
Is there something that can be done to add -3v to an existing power supply
where a +3v is present?
All other voltages are -24v, +5v, -12v (can a -12 be lowered?) S5v (what is
S5v?) and STB.

Adds to another question, what voltage can i expect the STB to be?
And what is S5v?
Without those connected the unit powers up but no functions work.

Bart Bervoets

Sure, the -12v supply can be lowered to -3 volts with either a zener
diode or a voltage regulator IC. For the zener diode solution
(simplest), you'll need to know approximately how much current is drawn
by the -3volt load. But it probably isn't much. You'll also need to be
sure that the -12v supply can support the added load.

Bill