Hoshizaki KM-300BAJ, Service Manual

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B. LED Lights and Audible Alarm Safeties
The control board includes LED indicator lights, audible alarm safeties, and an output
test feature. The “POWER OK” LED indicates control voltage and will remain on unless
a control voltage problem occurs. The “POWER OK” LED flashes continuously when the
bin is full and DV energizes for a maximum of 5 minutes to drain the water tank.
At startup, a 5 second delay occurs to stabilize the circuit. LEDs 4 through 8 energize
and sequence from initial startup as listed in the table below. Note that the order of the
LEDs from the outer edge of the board is 5, 6, 8, 9, 4, 7. For more information, see “II. A.
Sequence of Operation”.
Sequence Step LED
Energized
Components
Time LEDs are On
Min. Max. Avg.
1 Minute Fill Cycle 8 WV 60 seconds
Harvest Cycle 5, 6, 8 WV, HGV,
Comp
2 minutes 20 minutes 3 to 5 minutes
Last 0, 10, 30, or 50 seconds (adjustable by dip switch) of harvest, WV de-energizes
and PM energizes (LEDs 5, 6, and 7 are on)
Freeze Cycle
5, 7
Comp, PM,
FMS
5 minutes freeze timer
setting
25 to 30 minutes
Pump-Out Cycle 5, 6, 4, 7 Comp, HGV,
DV, PM
10 seconds 20 seconds factory default
setting
The built in safeties shut down the unit and have alarms as listed below.
No. of Beeps
(every 3 sec.)
Type of Alarm Notes
1
High Evaporator Temp.
(temperature > 127°F (53°C))
Check for harvest problem (stuck HGV or
relay), hot water entering unit, stuck HM, or
shorted thermistor.
2
Harvest Backup Timer
(harvest > 20 min. for two
cycles in a row)
Check for open thermistor, HGV not
opening, TXV leaking by, low charge,
inefficient Comp, or WRV leaking by.
3
Freeze Timer
(freeze > specified setting for
two cycles in a row)
Timer is factory set using S1
dip switch 9 & 10
Check for a float switch stuck closed (up),
WV leaking by, HGV leaking by, PM not
pumping, TXV not feeding properly, low
charge, or inefficient Comp.
To reset the above safeties, press the “ALARM RESET” button with the power supply
on.
6
Low Voltage
(92Vac ± 5% or less)
“POWER OK” LED will turn off if voltage
protection operates.
The control voltage safeties automatically
reset when voltage is corrected.
7
High Voltage
(147Vac ± 5% or more)
Legend: Comp –compressor; DV –drain valve; FMS –self-contained fan motor; HGV –hot
gas valve; PM –pump motor; TXV –thermostatic expansion valve; WRV –water
regulating valve; WV –inlet water valve