Hoshizaki KM-1301SRH-E, KM-1301SAH-E, KM-1301SWH-E service manual Control Board Check

B. 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.

Alarm Reset: If the control board is in alarm (beeping), press the "ALARM RESET" button on the control board while the control board is beeping. WARNING! Risk of electric shock. Care should be taken not to touch live terminals. Once reset, the unit starts at the 1-minute fill cycle. For audible alarm information, see "II.C.1.a) 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 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

"II.C.2.a) Default Dip Switch Settings."

2)Move the control switch to the "ICE" position. If the red "POWER OK" LED is on, the control voltage is good. If the red "POWER OK" LED is off on a thermostatic bin control unit (KM-1301SAH-E), clear ice away from the thermostatic bin control bulb in the storage bin area. If no ice is near the thermostatic bin control bulb or the red "POWER OK" LED does not come on even after clearing away ice, check the thermostatic bin control. See "IV.C.1. Thermostatic Bin Control Check." If the thermostatic bin control is okay (closed) or you are diagnosing a mechanical bin control unit and the red "POWER OK" LED is off, check the fuse, control switch contacts, high-pressure switch, and control transformer secondary circuit. Transformer output is 10.5V at 115V primary input. If the secondary circuit has proper voltage and the red LED is off, the control board is bad and should be replaced.

If the secondary circuit does not have proper voltage, check the control transformer primary circuit. Check for 115V at the control board K1 ten-pin connector. Check the #10 pin (BR wire) to a white neutral wire for 115V. (Always choose a white neutral wire to establish a good neutral connection when checking voltages.) For additional checks, see "IV.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. The correct lighting sequence is 1, 4, 3, 2. Note that the order of the LEDs from the outer edge of the control board is 1, 4, 3, 2. Components (e.g., compressor) will cycle during the test. Following the test, the icemaker resumes operation. If the LEDs do not light as described above, the control board is bad and should be replaced.

4)To verify voltage output from the control board to the components, slide the control board K1 ten‑pin connector out far enough to allow multimeter lead contact. With the unit in the cycle to be tested, check output voltage from the corresponding pin on the control board K1 ten‑pin connector to ground. If output voltage is not found and the appropriate LED is on, the control board is bad and should be replaced.

39