FSR ML-116 PSA Power Supply Troubleshooting - Manual

ML116psa.doc 3/19/2004
ML-116 PSA Power Supply Troubleshooting
CAUTION: ALWAYS REMOVE AC POWER BY UNPLUGGING THE POWER CORD
BEFORE OPENING POWER SUPPLY AND REPLACING FUSES.
Please read this BEFORE attempting any repairs.
Always power down when plugging an unplugging any components, modules and wall
plates. DO NOT "HOT PLUG". Do this between all the steps below.
The 5 volt indicator LED on the ML-PSA will be out in this condition. A blown 5 volt (5
amp) fuse usually indicates a short or mis-wire on the wall plate cabling. Fuses also
can blow as a result of installing or removing the wall plate while it is powered. Use the
procedure below to isolate this condition.
The attached illustrations show fuse locations on the ML-PSA PC board. Remove the
six cover screws and cover to access the PC board. Replace the 5 volt fuse as shown
on the attached sheet. There is a spare fuse on the power supply pc board. After
replacement, turn on the power supply with the output cable disconnected from the
REG card on the ML-116 ACU rack. See if all the lights on the power supply are lit.
Before attempting to operate the ML-116 you should first try to isolate a potential short
by reconnecting each load one at a time. If the fuse blows after a component is
plugged in, suspect a short on that component. It is a good idea to have spare fuses
on hand. Contact FSR for replacement fuses if they cannot be obtained locally.
Always power down when plugging an unplugging during these steps:
Remove all the wall plate connectors from the CPU card.
Pull back all of the cards in the rack so that they are not connected. It is not necessary
to remove them completely.
Attach the power supply to the "REG" card first.
If the three power indicator LED’s stays on
Plug in the “REG” card
Then plug in the CPU card
Then the other cards one at a time
Finally, the wall plate lines one at a time. If plates are “daisy chained” you will have to
test them one by one if that branch is suspect.
If all goes well and the new fuse does not blow try to operate the system. You should be back to "normal"
operation. This is a good way to isolate a short in the system and is well worth the time. Be very careful not to
connect the power supply connector into any of the wall plate bus connectors.