Hoshizaki DCM-271BAH-OS Service Manual page 16

• "DRAIN" Position: When control switch is in the "DRAIN" position, CB K9 connector
pin #1 (W/BK) and pin #2 (W/BK) are closed. 0VDC is present between pin
#1 (W/BK) and pin #2 (W/BK). If not, check control switch position and continuity.
Next, confirm 5VDC is present between both CB K9 connector pin #1 (W/BK) and
pin #2 to CB red K4 connector, pin closest to CB black K3 connector. If 5VDC is not
present on both pins, replace CB.
b) High-Pressure Switch (HPS)
CB K9 connector pins #3 (Y) and #4 (Y): When HPS is closed, 5VDC is present
between both CB K9 connector pins #3 (Y) and pin #4 (Y) to CB red K4 connector
pin closest to CB black K3 connector. If 5VDC is not present on pin #3 (Y) or pin
#4 (Y), replace CB. If 5VDC is present on CB K9 connector pin #3 (Y) and not on CB
K9 connector pin #4 (Y), HPS is most likely open. CB sounds a 3-beep alarm. Check
HPS continuity. If HPS is open and CB is not in alarm, replace CB.
c) Compressor Control Relay (CCR)
CB K9 connector pins #5 (W/O) and #6 (W/O): When CCR is de-energized (GM off),
CCR terminals #3 and #5 are open and 5VDC is present between CB K9 connector
pin #5 (W/O) and CB K9 connector pin #6 (W/O). If 5VDC is not present, check CCR
continuity between terminals #3 and #5. If closed and CCR is de-energized, replace
CCR. Check for 5VDC at CB K9 pin #5 (W/O) and CB red K4 pin #1 (pin closest to CB
black K3). If 5VDC is not present, replace CB. When CCR is energized, CCR terminals
#3 and #5 close and 0VDC is present between CB K9 pin #5 (W/O) and pin #6 (W/O).
5VDC is present between CB K9 pin #5 (W/O) to CB red K4 pin #1 (pin closest to CB
black K3) and CB K9 pin #6 (W/O) to CB red K4 pin #1 (pin closest to CB black K3).
If GM is energized and CCR terminals #3 & #5 are open, an 8-beep alarm occurs.
See "III.B. LED Lights and Audible Alarm Safeties." If CCR terminals #3 and #5 are
closed, Comp delay timer starts. If Comp does not energize after Comp delay timer
terminates, replace CB.
Component
Control Switch "DRAIN" Position
High-Pressure Switch (HPS)
Compressor Control Relay (CCR)
(CCR relay terminals #3 W/O and #5 W/O)
Multimeter
5VDC
Red Test Lead
Red test lead
to CB red
K4 pin #1 (pin
closest to CB
black K3)
5VDC CB K9 Connector
Black Test Lead
Fig. 1
Control Board K9 Connector
Pin # (Wire Color)
#1 (W/BK) and #2 (W/BK)
#3 (Y) and #4 (Y)
#5 (W/O) and #6 (W/O)
"DRAIN" Position on
Control Switch
(W/BK)
High-Pressure Switch (HPS) (Y)
Compressor Control Relay (CCR)
CCR Terminals #3 (W/O) and #5 (W/O)
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