This ice maker was brought to my shop it had a problem with this electronic PC
board now this board controls everything on the ice maker when it
takes water in the size of the cubes when it drops the
cubes and this board is faulty very expensive
to replace so i'll show you how i disconnect this board and make
this ice maker run with a relay and two
thermostats now this thermostat at the bottom here
is a Ranco we refer to as a double door thermostat it's got a range of minus 26
and plus three but we're gonna alter on that
now what this thermostat does this little relay is connected to the
thermostat when you put a thermostat in the
cycle position the relay contacts closes
and when you turn it open so all this thermostat really does is
switch this relay on and off now this thermostat
the the bulb the sensor i've mounted it inside here if you have
a look i put it on with these little cable ties
it goes in here and it goes to this thermostat
now normally on these ice makers when this
little tray down here gets close to about -25
the ice cubes are the right size then it has to go onto a hot gas cycle
to release the ice cubes and that are all run through this thermostat here
but we have to alter on the settings because
on this thermostat it says
constant in plus 3.5 now 3.5 is a temperature where
the thermostat will switch on but we want it much warmer than 3.5
we want at least 10 to 12 degrees celsius and what i do is
i just alter on the calibration screws here to alter that
but what this thermostat all this thermostat does is
switch the relay on and off now this relay
has got a normally open and a normally closed contact now
this ice maker has got two modes in one mode
the compressor runs the water pump runs and the water circulates and the fan
motor runs but when the ice cubes are formed it
goes into the other mode compressor carries on running the pump
stops but the hot gas solenoid activates
to allow hot gas into the chamber to release the ice cubes
and once the ice cubes drops this thermostat switches this relay onto
the mode again where it's at the water pump will run and it will
refrigerate and you have to just get your calibrations
right so the cubes are the right size when this cycles and all the cubes must
drop before this sets back switches the relay
on again now we've got a second thermostat here
this second thermostat is a normal it's an Aruki single door
thermostat and that's the temperature range that
works at but we don't want that temperature range
this this thermostat is for when the bin is full
to switch it off now if you have a look inside the bin
and you'll see this tube here I've spiraled the thermostat
bulb around this so once it's full and
ice cubes touches this it should switch it off
but not on the temperatures that set here
so what i do with this Aruki thermostat
if you open this back cover here you'll find a little screw
and i tighten the screw to the point where
where you get the shortest differential
now the differential is the period between
thermostats switching off and on so when i switch it off
in the off position then the compressor should cycle and
it should break all the electricity so everything should stop because your bin
is full and when this switch is on again which i'll calibrate to a temperature
where the ice cubes activate it it will switch it on again so this is
for the bin being full that is the thermostat that it cycles on
and this is the relay that activates everything
now this has got a water pump connected to the mains that
allows water in so on the mode when it's on hot gas
i put power to the solenoid so the whole defrost period it will take water in
so you must just adjust the tap to get the right amount of water in
once it's got it goes out of the defrost mode that
after dropping the ice cube and it goes into the mode it's in now
for running then it switches the solenoid off and
then it obviously has enough water for the next cycle
and that's how i disconnect the electronic boards
and replace it with mechanical parts
okay i've mounted the two thermostats the one on top of the other on brackets
and the relay i've mounted behind there on their base
and i put some cable ties on the wires to neaten it up
but now it's working fine this bottom thermostat
will determine the size of the cube and what i've done is i've got cubes
about this size in the middle of the range so we can
either turn it this way to make the cubes
bigger or smaller the size you want but on a half a turn
that's the size and this thermostat i've calibrated also
about on a half a turn when the ice would build up and
just look inside here when the ice builds up in the
dish and it touches this sensor this is the thermostat bulb it will
switch everything off until the ice is melted and restart
again and that's adjusted on the top
thermostat so there's a job complete
this electronic board i've taken out and the two thermostats in a relay works
perfectly well