Appendix C: Ncm100 Power Supply Troubleshooting; Introduction; Products Affected; Recommended Action - Johnson Controls 300 Series Manual

Appendix C: NCM100 Power Supply
Troubleshooting

Introduction

Products Affected

Recommended Action

Network Control Module 300 Series Technical Bulletin
Some NU-PWR101-0 power supplies shipped prior to the end of 1995
experience random failures that become evident only after cycling the
line power. After restoring line power, the power supply is dead with
no output. The problem is due to component aging, and the likelihood
of its occurring increases with time. Older power supplies operating at
high ambient temperatures aggravate the problem.
These power supplies may fail one at a time in a seemingly random
pattern, or they may fail in large numbers, all at once, particularly after
events such as building power outage or standby power testing. Note
that these power supply failures are a function of component aging and
will likely occur after many years (7-10) of service.
Some NU-PWR101-0 and NU-PWR101-700 power supplies
(at Revision A through F) are affected. These power supplies have a
manufacturing date code 9522 or earlier. The power supply at
Revision G or later, regardless of date code, is redesigned to further
extend the life.
The revision level of installed boards can be verified only by powering
down the NU-PWR101 and examining the label on the side of the
assembly. Make sure a replacement NU-PWR101 is readily available
in case of failure during verification of the revision level.
You and your customers should assess the risk and plan appropriate
action. It is important to address those customers who have mission
critical jobs or a large number of affected NU-PWR101 power
supplies. Strongly encourage those customers to take preventive action
to minimize the possibility of a disruption to the operation of their
systems.
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