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5.4.1 Turn On and Shut Down Fault Isolation
System "turn-on" problems occur when the system fails to turn on and stay on with activation of the key
switch. System "Shutdown" refers to the system main contactor de-energizing after the system has
successfully turned on.
If the system fails to turn on, determine if there is power to the unit and through the circuit breaker to the main
contactor and isolation transformer. Determine if the main contactor is energizing when the keyswitch is held
in the start position (do the system fan and pump start running?). If not, check the circuit breaker, isolation
transformer thermal switch and fuses F8/F9. If the contactor is energizing in the start position, but de-
energizing when the keyswitch is released, check for sufficient coolant flow (coolant level, pump, line
restrictions, etc.), waterflow switch S3, K2 and K1 (Refer to Interlock schematic in Section 8).
If the system shuts down after being turned on, and the circuit breaker is not tripping, use the Interlock
schematic in Section 8 to troubleshoot the main contactor interlock loop. Note that the software and
microprocessor can turn off the main contactor. The 24 VAC loop to the main contactor can be broken by the
thermal switch in the isolation transformer, the waterflow switch, hold on relay K3, or the fuse F10.
If the circuit breaker is tripping, check for proper transformer tapping. If the tripping is associated with firing
(or charging of the main capacitor), it is probably associated with the HVPS. If not, attempt to isolate the
tripping to one of the isolation transformer secondary loads by removing fuses until the circuit breaker no
longer trips (smart fan fuse, pump fuse, display P/S fuse, then interlock loop fuse).
5.4.2 “No Fault Code Reported” Fault Isolation
Some system malfunctions cannot be reported at the Control Panel. These include those malfunctions which
interfere with the operation of the microprocessor, malfunctions in the hardware that drives the display used
to report errors, and miscellaneous circuits/functions which are not directly monitored/tested by the
software.
If the malfunction is associated with a particular function (e.g., the system doesn’t respond to the footswitch, or
to some front panel control), troubleshoot that function, referring to the circuit descriptions in Section 4.
If the system turns on, but the malfunction is more general (e.g., the self test sequence doesn’t run, Control
Panel does not respond) check for proper DC power supply voltages, isolation transformer tapping,
interconnection problems, or for some problem with the microprocessor (are they running?)/Control Panel
interface. If the problem can not be isolated to a particular circuit, replace the CPU PCB.
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