I've got a Fisher and Paykel fridge freezer model E240B but the
thermostat isn't working. The motor runs continuously and eventually
even the fridge compartment freezes up. I've taken the thermostat to
pieces as much as I can. The adjustment knob connects to a 1K
potentiometer that is working fine. Tucked behind the cooling plate are 3
sensors of some sort. One black one about 20 mm long. Is this the
thermocouple? The other 2 are discs about 10 mm diameter. I thought at
the start that they might be magnetic designed to stick to the back of
the cooling plate but they aren't magnetic. Has anybody any idea what
might be wrong. How can I test these components? What are they?

Photos he-
https://ibb.co/dcCyqPt
https://ibb.co/pLwnRHm

Thanks.

On Sat, 09 Feb 2019 06:12:40 GMT, Kit Jackson wrote:

The adjustment knob connects to a 1K
potentiometer that is working fine. Tucked behind the cooling plate are 3
sensors of some sort. One black one about 20 mm long. Is this the
thermocouple?

Yes, the sensor, but NTC or so, and not a thermocopuple.

The other 2 are discs about 10 mm diameter. I thought at
the start that they might be magnetic designed to stick to the back of
the cooling plate but they aren't magnetic.

3M gel connectors: all the do is connect and seal out water.

Has anybody any idea what
might be wrong. How can I test these components? What are they?

The other bits look like the connectors to the light bulb.

The interesting parts are elsewhere... probably in back.


Thomas Prufer

On Sat, 09 Feb 2019 08:37:15 +0100, Thomas Prufer wrote:

On Sat, 09 Feb 2019 06:12:40 GMT, Kit Jackson
wrote:

The adjustment knob connects to a 1K potentiometer that is working fine.
Tucked behind the cooling plate are 3 sensors of some sort. One black
one about 20 mm long. Is this the thermocouple?

Yes, the sensor, but NTC or so, and not a thermocopuple.


Right, so this is a thermistor and the internet tells me this is likely
to have a resistance of between 100 and 10K Ohms in the temperature range
we are interested in, matching well enough the 1K pot in a voltage
balancing circuit. I'd guess this is very unlikely to fail then, but if
it does fail it will either be a short circuit or an open circuit. If I
can get some probes at it I'll try to measure its resistance but it looks
like it has been potted up.

The other 2 are discs about 10 mm diameter. I thought at the start that
they might be magnetic designed to stick to the back of the cooling
plate but they aren't magnetic.

3M gel connectors: all the do is connect and seal out water.


This looks like I'm barking up the wrong tree then. Lets forget them.

Has anybody any idea what might be wrong. How can I test these
components? What are they?

The other bits look like the connectors to the light bulb.

The interesting parts are elsewhere... probably in back.


I'll have a look round the back near the compressor. Any clues what I'm
looking for? Is this likely to be a diy job?


Thomas Prufer

Thanks for your hep so far.
Kit Jackson

Kit Jackson wrote

I've got a Fisher and Paykel fridge freezer model E240B but the
thermostat isn't working. The motor runs continuously and eventually
even the fridge compartment freezes up. I've taken the thermostat to
pieces as much as I can. The adjustment knob connects to a 1K
potentiometer that is working fine. Tucked behind the cooling plate are 3
sensors of some sort. One black one about 20 mm long. Is this the
thermocouple?

More likely to be an electronic temperature sensor.

The other 2 are discs about 10 mm diameter. I thought
at the start that they might be magnetic designed to stick
to the back of the cooling plate but they aren't magnetic.

They look like just where the wire goes thru the wall.

Has anybody any idea what might be wrong.

Either that temperature sensor has failed or what
is reading it has failed. Or a wire has come adrift
where you can't see it.

How can I test these components?

By replacing it is the obvious way.

What are they?

Photos he-
https://ibb.co/dcCyqPt
https://ibb.co/pLwnRHm

On Saturday, 9 February 2019 08:15:33 UTC, Kit Jackson wrote:
On Sat, 09 Feb 2019 08:37:15 +0100, Thomas Prufer wrote:
On Sat, 09 Feb 2019 06:12:40 GMT, Kit Jackson
wrote:

The adjustment knob connects to a 1K potentiometer that is working fine.
Tucked behind the cooling plate are 3 sensors of some sort. One black
one about 20 mm long. Is this the thermocouple?

Yes, the sensor, but NTC or so, and not a thermocopuple.


Right, so this is a thermistor and the internet tells me this is likely
to have a resistance of between 100 and 10K Ohms in the temperature range
we are interested in, matching well enough the 1K pot in a voltage
balancing circuit. I'd guess this is very unlikely to fail then, but if
it does fail it will either be a short circuit or an open circuit. If I
can get some probes at it I'll try to measure its resistance but it looks
like it has been potted up.

The other 2 are discs about 10 mm diameter. I thought at the start that
they might be magnetic designed to stick to the back of the cooling
plate but they aren't magnetic.

3M gel connectors: all the do is connect and seal out water.


This looks like I'm barking up the wrong tree then. Lets forget them.

Has anybody any idea what might be wrong. How can I test these
components? What are they?

The other bits look like the connectors to the light bulb.

The interesting parts are elsewhere... probably in back.


I'll have a look round the back near the compressor. Any clues what I'm
looking for? Is this likely to be a diy job?


Thomas Prufer

Thanks for your hep so far.
Kit Jackson

I wuoldn't say that a thermistor was unlikely to fail, nor that it would surely go sc or oc.

A temp sensor coming adrift from the evaporator can cause the problem, as can a faulty sensor. I'm a lot more familiar with ye olde frosting fridges & freezers, and don't know whether your stat should be attached to the evap or not.


NT

Yes if you can ascertain what the changes in the signal are from the device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a connection to
and from the control or sensor, but you need to find the board and see if
its something you can replace. Sods law will dictate its in the most
inaccessible place possible.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Thomas Prufer" wrote in message
...
On Sat, 09 Feb 2019 06:12:40 GMT, Kit Jackson
wrote:

The adjustment knob connects to a 1K
potentiometer that is working fine. Tucked behind the cooling plate are 3
sensors of some sort. One black one about 20 mm long. Is this the
thermocouple?

Yes, the sensor, but NTC or so, and not a thermocopuple.

The other 2 are discs about 10 mm diameter. I thought at
the start that they might be magnetic designed to stick to the back of
the cooling plate but they aren't magnetic.

3M gel connectors: all the do is connect and seal out water.

Has anybody any idea what
might be wrong. How can I test these components? What are they?

The other bits look like the connectors to the light bulb.

The interesting parts are elsewhere... probably in back.


Thomas Prufer

Is this a frost free design or your basic jobby. Either way though I'd
imagine either is at least one relay controlling the compressor on the pcb.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Kit Jackson" wrote in message
...
On Sat, 09 Feb 2019 08:37:15 +0100, Thomas Prufer wrote:

On Sat, 09 Feb 2019 06:12:40 GMT, Kit Jackson
wrote:

The adjustment knob connects to a 1K potentiometer that is working fine.
Tucked behind the cooling plate are 3 sensors of some sort. One black
one about 20 mm long. Is this the thermocouple?

Yes, the sensor, but NTC or so, and not a thermocopuple.


Right, so this is a thermistor and the internet tells me this is likely
to have a resistance of between 100 and 10K Ohms in the temperature range
we are interested in, matching well enough the 1K pot in a voltage
balancing circuit. I'd guess this is very unlikely to fail then, but if
it does fail it will either be a short circuit or an open circuit. If I
can get some probes at it I'll try to measure its resistance but it looks
like it has been potted up.

The other 2 are discs about 10 mm diameter. I thought at the start that
they might be magnetic designed to stick to the back of the cooling
plate but they aren't magnetic.

3M gel connectors: all the do is connect and seal out water.


This looks like I'm barking up the wrong tree then. Lets forget them.

Has anybody any idea what might be wrong. How can I test these
components? What are they?

The other bits look like the connectors to the light bulb.

The interesting parts are elsewhere... probably in back.


I'll have a look round the back near the compressor. Any clues what I'm
looking for? Is this likely to be a diy job?


Thomas Prufer

Thanks for your hep so far.
Kit Jackson

On Sat, 09 Feb 2019 09:37:57 +0000, Brian Gaff wrote:

Yes if you can ascertain what the changes in the signal are from the
device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a
connection to and from the control or sensor, but you need to find the
board and see if its something you can replace. Sods law will dictate
its in the most inaccessible place possible.
Brian

This isn't looking too good. The control unit contains a circuit board.
One of the connectors on the cover is marked "T SENS". There's 4 wires
on the connector, presumably from the fridge and freezer parts. One pair
gives a resistance of 2.85K Ohms and the other 2.95K Ohms. The ambient
temperature is 20C. Is that about what might be expected? I'll put it
all back together and turn the fridge on again and re-measure later to
see if the values change.

There's a photo of the circuit board here but I don't fancy having to
replace components on that. Is there anything I can usefully measure on
the board?

Photo: https://ibb.co/gDrCn82

Kit Jackson

On Sat, 09 Feb 2019 20:42:14 +0000, Kit Jackson wrote:

On Sat, 09 Feb 2019 09:37:57 +0000, Brian Gaff wrote:

Yes if you can ascertain what the changes in the signal are from the
device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a
connection to and from the control or sensor, but you need to find the
board and see if its something you can replace. Sods law will dictate
its in the most inaccessible place possible.
Brian

This isn't looking too good. The control unit contains a circuit board.
One of the connectors on the cover is marked "T SENS". There's 4 wires
on the connector, presumably from the fridge and freezer parts. One
pair gives a resistance of 2.85K Ohms and the other 2.95K Ohms. The
ambient temperature is 20C. Is that about what might be expected? I'll
put it all back together and turn the fridge on again and re-measure
later to see if the values change.

There's a photo of the circuit board here but I don't fancy having to
replace components on that. Is there anything I can usefully measure on
the board?

Photo: https://ibb.co/gDrCn82

Kit Jackson

Follow up :-

The thermistor now reads 3.4K Ohms at 10C and the other thermistor for
the freezer reads 6K Ohms. So I guess the good news is that the
thermistors are OK. But I guess the bad news is that the problem is on
the circuit board. Is it un-repairable?

Kit Jackson

"Kit Jackson" wrote in message
...
On Sat, 09 Feb 2019 20:42:14 +0000, Kit Jackson wrote:

On Sat, 09 Feb 2019 09:37:57 +0000, Brian Gaff wrote:

Yes if you can ascertain what the changes in the signal are from the
device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a
connection to and from the control or sensor, but you need to find the
board and see if its something you can replace. Sods law will dictate
its in the most inaccessible place possible.
Brian

This isn't looking too good. The control unit contains a circuit board.
One of the connectors on the cover is marked "T SENS". There's 4 wires
on the connector, presumably from the fridge and freezer parts. One
pair gives a resistance of 2.85K Ohms and the other 2.95K Ohms. The
ambient temperature is 20C. Is that about what might be expected? I'll
put it all back together and turn the fridge on again and re-measure
later to see if the values change.

There's a photo of the circuit board here but I don't fancy having to
replace components on that. Is there anything I can usefully measure on
the board?

Photo: https://ibb.co/gDrCn82

Kit Jackson

Follow up :-

The thermistor now reads 3.4K Ohms at 10C and the other thermistor for
the freezer reads 6K Ohms. So I guess the good news is that the
thermistors are OK. But I guess the bad news is that the problem is on
the circuit board. Is it un-repairable?

Nothing is unrepairable but it may make more sense to replace it.

On 09/02/2019 08:15, Kit Jackson wrote:
On Sat, 09 Feb 2019 08:37:15 +0100, Thomas Prufer wrote:

On Sat, 09 Feb 2019 06:12:40 GMT, Kit Jackson
wrote:

The adjustment knob connects to a 1K potentiometer that is working fine.
Tucked behind the cooling plate are 3 sensors of some sort. One black
one about 20 mm long. Is this the thermocouple?

Yes, the sensor, but NTC or so, and not a thermocopuple.


Right, so this is a thermistor and the internet tells me this is likely
to have a resistance of between 100 and 10K Ohms in the temperature range
we are interested in, matching well enough the 1K pot in a voltage
balancing circuit. I'd guess this is very unlikely to fail then, but if
it does fail it will either be a short circuit or an open circuit. If I
can get some probes at it I'll try to measure its resistance but it looks
like it has been potted up.

The other 2 are discs about 10 mm diameter. I thought at the start that
they might be magnetic designed to stick to the back of the cooling
plate but they aren't magnetic.

3M gel connectors: all the do is connect and seal out water.


This looks like I'm barking up the wrong tree then. Lets forget them.

Has anybody any idea what might be wrong. How can I test these
components? What are they?

The other bits look like the connectors to the light bulb.

The interesting parts are elsewhere... probably in back.


I'll have a look round the back near the compressor. Any clues what I'm
looking for? Is this likely to be a diy job?


Thomas Prufer

Thanks for your hep so far.
Kit Jackson



You said it is a fridge/freezer I believe.

At least some of these have a single compressor which is controlled by
the freezer temp. The fridge as an after thought, sometimes by (for
example) a flap controlling air flow from the freezer. We had one like
this and the flap got stuck nearly closed. A wiggle and a clean and all
was fixed.

It could be as simple as 'gunge' blocking a flap or air flow.

On Sunday, 10 February 2019 07:29:03 UTC, Kit Jackson wrote:
On Sat, 09 Feb 2019 20:42:14 +0000, Kit Jackson wrote:
On Sat, 09 Feb 2019 09:37:57 +0000, Brian Gaff wrote:

Yes if you can ascertain what the changes in the signal are from the
device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a
connection to and from the control or sensor, but you need to find the
board and see if its something you can replace. Sods law will dictate
its in the most inaccessible place possible.
Brian

This isn't looking too good. The control unit contains a circuit board.
One of the connectors on the cover is marked "T SENS". There's 4 wires
on the connector, presumably from the fridge and freezer parts. One
pair gives a resistance of 2.85K Ohms and the other 2.95K Ohms. The
ambient temperature is 20C. Is that about what might be expected? I'll
put it all back together and turn the fridge on again and re-measure
later to see if the values change.

There's a photo of the circuit board here but I don't fancy having to
replace components on that. Is there anything I can usefully measure on
the board?

Photo: https://ibb.co/gDrCn82

Kit Jackson

Follow up :-

The thermistor now reads 3.4K Ohms at 10C and the other thermistor for
the freezer reads 6K Ohms. So I guess the good news is that the
thermistors are OK. But I guess the bad news is that the problem is on
the circuit board. Is it un-repairable?

Kit Jackson

You don't know whether the thermistors are ok until you know what resistance they should be. Bridging them with a resistor could at least tell you if the pcb is responding to temp changes.


NT

On Sat, 09 Feb 2019 20:42:14 GMT, Kit Jackson
wrote:

On Sat, 09 Feb 2019 09:37:57 +0000, Brian Gaff wrote:

Yes if you can ascertain what the changes in the signal are from the
device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a
connection to and from the control or sensor, but you need to find the
board and see if its something you can replace. Sods law will dictate
its in the most inaccessible place possible.
Brian

This isn't looking too good. The control unit contains a circuit board.
One of the connectors on the cover is marked "T SENS". There's 4 wires
on the connector, presumably from the fridge and freezer parts. One pair
gives a resistance of 2.85K Ohms and the other 2.95K Ohms. The ambient
temperature is 20C. Is that about what might be expected? I'll put it
all back together and turn the fridge on again and re-measure later to
see if the values change.

There's a photo of the circuit board here but I don't fancy having to
replace components on that. Is there anything I can usefully measure on
the board?

Photo: https://ibb.co/gDrCn82

Kit Jackson

You might be able to unsolder the two relays to test them with
external power.
--
Dave W

On 11/02/2019 12:51, Dave W wrote:
On Sat, 09 Feb 2019 20:42:14 GMT, Kit Jackson
wrote:

On Sat, 09 Feb 2019 09:37:57 +0000, Brian Gaff wrote:

Yes if you can ascertain what the changes in the signal are from the
device,
and measure it, then you know the pot is OK my guess is that the actual
electronics is faulty, for whatever reason, It could even be a
connection to and from the control or sensor, but you need to find the
board and see if its something you can replace. Sods law will dictate
its in the most inaccessible place possible.
Brian

This isn't looking too good. The control unit contains a circuit board.
One of the connectors on the cover is marked "T SENS". There's 4 wires
on the connector, presumably from the fridge and freezer parts. One pair
gives a resistance of 2.85K Ohms and the other 2.95K Ohms. The ambient
temperature is 20C. Is that about what might be expected?

yes.

I'll put it
all back together and turn the fridge on again and re-measure later to
see if the values change.

There's a photo of the circuit board here but I don't fancy having to
replace components on that. Is there anything I can usefully measure on
the board?

Probably not.

Photo: https://ibb.co/gDrCn82

Kit Jackson

You might be able to unsolder the two relays to test them with
external power.



--
Gun Control: The law that ensures that only criminals have guns.