Hoshizaki MRH/3, MWH KM-515MAH, MRH KM-901MAH, MWH(-M), KM-320MAH C. Control Board Check

Models: KM-320MAH MRH KM-600MAH KM-650MAH MWH(-M) MRH KM-901MAH MRH/3 MWH KM-515MAH MWH

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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.

Alarm Reset: If CB is in alarm (beeping), press the "ALARM RESET" button on CB while CB is beeping. WARNING! Risk of electric shock. Care should be taken not to touch live terminals. Once reset, the icemaker starts at the 1-minute fill cycle. For audible alarm information, see "III.B. LED Lights and Audible Alarm Safeties."

1)Check the dip switch settings to assure that S4 dip switch 3, 4, 7, 8, 9, 10 and S5 dip switch 1 through 5 ("G" CB) are in the factory default position. S4 dip switch 1, 2, 5, 6 are cleaning adjustments and the settings are flexible. For factory default settings, see

"III.C.1. Default Dip Switch Settings."

2)Move the control switch to the "ICE" position. If the red "POWER OK" LED is on, control voltage is good, continue to step 3. If the "POWER OK" LED is off, check CT secondary circuit. CT output is 10.5VAC at 115VAC primary input. If the secondary circuit has proper voltage and the red LED is off, replace CB.

If the secondary circuit does not have proper voltage, check CT primary circuit. Check for 115VAC at CB K1 connector pin #10 (BR) to neutral (W) for 115VAC. Always choose a white (W) neutral wire to establish a good neutral connection when checking voltages. For additional checks, see "II.G.1. No Ice Production."

3)The "OUTPUT TEST" button provides a relay sequence test. Make sure the control switch is in the "ICE" position, then press the "OUTPUT TEST" button. For the correct lighting sequence, see the table below. Note that the order of the LEDs from the outer edge of the control board is 1, 4, 3, 2. Components (e.g., compressor) cycle during the test.

Control

Correct LED

Board

Lighting Sequence

 

 

"E"

2, 3, 4, 1

 

 

"G"

1, 4, 3, 2

 

 

Following the test, the icemaker begins operation at the 1-minute fill cycle for both "E" and "G" control boards. If the LEDs do not light as described above, replace CB.

4)To verify voltage output from CB to the components, slide the CB K1 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 K1 connector to a neutral (W wire). If output voltage is not found and the appropriate LED is on, replace CB.

Legend: CB–control board; CT–control transformer

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Hoshizaki MRH/3, MWH KM-515MAH, MRH KM-901MAH, MWH(-M), MRH KM-600MAH KM-650MAH, KM-320MAH C. Control Board Check