Control Board Check - Hoshizaki KM-1301SAH/3 Service Manual

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 with power on. Once reset, the unit starts at
the 1-minute fill cycle. For audible alarm information, see "II.C.2.f) 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.3.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 "POWER OK" LED is off, check the control transformer
secondary circuit. The control transformer secondary circuit includes the cleaning valve
interlock switch. Make sure the interlock switch is closed; otherwise, no control voltage
is supplied to the K2 connector. 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. See "V.P. Removal and Replacement of Control Board."
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.F.1.[1] The icemaker will not start."
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. See "V.P. Removal
and Replacement of Control Board."
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. See "V.P.
Removal and Replacement of Control Board."
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