We have a ITT Power Systems PEC4071 1250W (5VDC@150/+12VDC@80A/-12VDC@20A)
switcher that appears to have gone bad (or is at least on the way out!).
The unit caries a Motorola part number and powers a VME based computer in a
piece of test equipment in our lab.

The symptoms are pretty straight forward: 99% of the time it will not start
up! This all started when the system was shut down for maintenance and we
went back to turn it on. Nothing; no fans; nothing. We pulled the unit and
let it sit for a few hours, and when we plugged it in it turned on.
However, when we turned it off, it would not come back up again for a couple
of hours. The second time we checked the output voltages and they all
looked good.

Does anyone know of ITT Power Systems still exists or who might have
purchased them?

Anyone happen to have a schematic? We are particularly interested in the 30
pin header connector which connects to the front control panel of the VME
chassis. There are 4 wires on this connector as follows:

BLACK Ground
WHITE -15VDC
VIOLET ??
GREY ??

Any ideas will be greatly appreciated!

Thanks!

Don

Michael,

We will look into that!

Thanks!

Don



"Michael A. Terrell" wrote in message
...
Don wrote:

We have a ITT Power Systems PEC4071 1250W
(5VDC@150/+12VDC@80A/-12VDC@20A)
switcher that appears to have gone bad (or is at least on the way out!).
The unit caries a Motorola part number and powers a VME based computer
in a
piece of test equipment in our lab.

The symptoms are pretty straight forward: 99% of the time it will not
start
up! This all started when the system was shut down for maintenance and
we
went back to turn it on. Nothing; no fans; nothing. We pulled the unit
and
let it sit for a few hours, and when we plugged it in it turned on.
However, when we turned it off, it would not come back up again for a
couple
of hours. The second time we checked the output voltages and they all
looked good.

Does anyone know of ITT Power Systems still exists or who might have
purchased them?

Anyone happen to have a schematic? We are particularly interested in
the 30
pin header connector which connects to the front control panel of the
VME
chassis. There are 4 wires on this connector as follows:

BLACK Ground
WHITE -15VDC
VIOLET ??
GREY ??

Any ideas will be greatly appreciated!

Thanks!

Don

Get an ESR meter and start checking all the electrolytics, or just
replace them all with low ESR 105° C electrolytic capacitors. Dried out
electrolytic capacitors cause most intermittent failures in switching
power supplies.
--


Michael A. Terrell
Central Florida