Control Board Check - Hoshizaki F-500BAJ Service Manual

C. Control Board Check
Before replacing a control board that does not show a visible defect and that you suspect
is bad, always conduct the following check procedure. This procedure will help you verify
your diagnosis.
1) Check CB S1 dip switch settings to assure that they are in the factory default position.
For factory default settings, see "III.B.1. Default Dip Switch Settings."
Note: S1 dip switch 7 determines bin control application:
BC: S1 dip switch 7 in the "OFF" position.
2) Move the power switch to the "ON" position and move the control switch to the "ICE"
position. The "POWER OK" LED turns on. Diagnosis "POWER OK" LED: Check that
the CB "POWER OK" LED is on. If not, check for proper supply voltage (115VAC) input
to the control transformer (power switch, power supply cord, breaker, and fuse). Next,
check for proper low-voltage (24VAC) output from the control transformer and that
the fuse is good. Check for 24VAC at CB K8 #1 (W/R) to CB K8 #2 (LBU). If 24VAC is
present and the "POWER OK" LED is off, replace CB.
3) 5VDC Output Checks:
CB K9 Connector: Control Switch (CB K9 #1 and #2) (open contacts for icemaking,
closed contacts for drain), High-Pressure Switch (CB K9 #3 and #4), Compressor
Control Relay (K9 #5 and #6).
CB K8 Connector: Bin Control (K8 #3 and #4) and Float Switch (K8 #5 (common),
#6 (lower), and #7 (upper)).
When checking 5VDC control voltage, always place the red positive test lead from
the multimeter to the CB white K5 pin closest to the CB red K4 connector. See Fig. 1.
Then place the black negative test lead from the multimeter to the corresponding pin to
complete the 5VDC check.
Red positive test lead
to K5 pin closest to K4
connector
Red Positive
Test Lead
5VDC
Black Negative
Test Lead
Multimeter
Control Board K9 Connector
Fig. 1
19
Control Switch
white/black (W/BK)
High-Pressure Switch
yellow (Y) wires
Compressor Control Relay/
Gear Motor Protect Relay
(terminals #3 and #5)
white/orange (W/O)