RE: [CAD_CAM_EDM_DRO] Info on Jumping a PC power supply?

PC Power supplies are cheap, but be well aware PC power supplies are CHEAP.

What I mean is every corner has been cut to get them as cheap as possible,
in the UK they are less than £9 each, I couldn’t buy the fan for that. As
such they aren’t that reliable, they will run for a year or so then fall
over, they may also last for ten years without problem. About 20% of the
time they fall over nasty voltages exist on the output connector. About 5%
of the time they will damage the PC. Of this 5% some suffer minor faults and
can be repaired by swapping cards, about 1 in 5 will suffer damage where
every alternative card you plug in will fry immediately, so nowadays if the
supply has damaged the PC, most will scrap it. We believe these are ones
that have failed due to mains born transients but there is insufficient
proof.

This is a normal trend recently published as recognised by many
manufacturers and service companies, it also fits my experience, when we
used to commercially build and service many machines.

If you are going to use a PC supply, just consider what you have hanging on
the outputs and how susceptible it may be when the supply fails. You could
run a policy to change the supply every 12 to 18 months, which was a
standard practice in many service groups. You might also be better off
buying a slightly dearer supply either PC one or other. Many commercial
equipment switch modes are dearer but far more reliable. For external non PC
loads like motors, I have also found some remain well regulated as rapid
loads like a motor or even relay are switched on, for some the output
voltage will bounce really wildly, and some all output voltages will bounce.



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of jeff spinner
Sent: 24 June 2007 00:15
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Info on Jumping a PC power supply?



I purchased a kit from stepperworld.com they sent it with a 550w power
supply and nema 23 steppers. I hooked up the supply they gave me and it
worked for a little bit then stopped. I went to frys and bought a new one
but I jumped it the same way that they did but I only get the 5v part to
work and not the 12v part. I took some power from the pc I'm using to run
the machine but would rather use the new supply for the motors alone. ? I
think there are two circuits to jump out for the new power supply.





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