Johnson Controls 300 Series Manual page 57

Network Control Module 300 Series Technical Bulletin
NCM350-8 Resets or Malfunctions Due to Circuit Shorting
The Erasable Programmable Read-Only Memory (EPROM) covering
on NCM350-8s is conductive to shield electromagnetic signals from
the NCM. The ROM150 cover may come in contact with the NCM
motherboard or the card installed in the first ISA option slot. If this
happens, some portion of either circuit can become shorted and cause
the NCM to reset or exhibit other signs of malfunction.
Note: Newer NCM350-8 ROM150 covers have factory-installed
insulation that prevents shorting. Before proceeding with the following
steps, check to see if your NCM350-8 has factory-installed insulation.
1. Before applying power to the NCM, check the top edge of the
ROM150 cover to make sure it is not hooked under one or more of
the component solder trails from the board being inserted. If the
cover is hooked, remove and reinsert the board while holding the
cover away from the bottom of the board.
2. Check that the ROM150 cover is not bending to touch one end of
the motherboard. Move the cover away from the motherboard
before applying power to the NCM.
Note: Inspection and proper insulation of ISA boards and enclosure
prevent most shorting instances. To ensure shorting does not occur,
apply electrical tape to the top and lower edges of the ROM150 cover.
Remove the cover and measure the three edges (one on top and two on
the bottom). Cut tape to those lengths and apply to the cover so each
piece of tape straddles the edges. Half of the tape should be on either
side of the surrounding edge.
If You Cannot Communicate at All with the NCM
Note: The following section applies only if you are using an NCM
on the ARCNET N1 LAN.
Unless the NCM has worked previously, or only one NCM on the N1
is not communicating, this symptom points to an error in the software
configuration, ARCNET card setup, or cabling.
1. Ensure that the NCM is correctly addressed on the OWS (the
NCM address must match what the OWS thinks it is, and the NCM
archive address must point to the appropriate archive PC).
2. If the N1 transmit LED (at the top of the ARCNET card) blinks
frequently while yielding intermittent or no communication, the
N1 is constantly reconfiguring. This is a clue that there are
duplicate addresses on the LAN or that there is a problem with the
N1 wiring. Make sure that the N1 connectors do not short to the
NCM enclosure or other metal grounds.
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