Control Board Check - Hoshizaki IM-500SAB Service Manual

C. Control Board Check
Before replacing CB 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. Always choose a white (W) neutral wire to establish a good neutral connection
when checking voltages.
Error Codes: If CB is in error (E1, E2, EE(3-9), EE(EA), EE(EC), EE(Ed)),
see "III.F. Error Codes."
1) Move CS to the "ICE" position. If CB "on" display turns on, control voltage is good,
continue to step 2. Diagnosis CB "on" Display: If CB "on" display is off, check CT
secondary circuit. CT output is 10.5VAC at 115VAC primary input. If the secondary
circuit has proper voltage and CB "on" display is off, replace CB.
If the secondary circuit does not have proper voltage, check CT primary circuit. Check
for 115VAC at 5A fuse (BR) to neutral (W). If 115VAC is not present, check power supply
and breaker. If 115VAC is present, check for 115VAC at CS terminal #2 (DBU) to neutral
(W). If 115VAC is not present, check 5A fuse continuity. If 115VAC is present, check
for 115VAC at CS terminal #1 (R) to neutral (W). If 115VAC is not present, replace CT.
If 115VAC is present, check for 115VAC at HPS (LBU) to neutral (W). If 115VAC is not
present, see "II.B.1.1)b). HPS Diagnosis." If 115VAC is present, and secondary circuit
does not have proper voltage, . replace CT.
2) To verify voltage output from CB to the components, slide CB connector out far enough
to allow multimeter lead contact. With the icemaker in the cycle to be tested, check
output voltage from the corresponding pin on CB connector to a neutral (W wire).
If output voltage is not found, replace CB.
3) Confirm BC communication and shutdown sequence: Move CS to the "ICE" position.
Once the startup cycle starts, press and hold the BC actuator paddle. CB shuts down
the appliance after the next harvest cycle. If not, confirm BC status. See "II.D.1. Bin
Control Check." If BC checks okay, replace CB.
Legend: BC–bin control; CB–control board; CS–control switch; CT–control transformer;
HPS–high-pressure switch
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