Miele electronic freezer

[beano1939]

I have an f7131 s freezer which is too cold.It is not switching off so the temperature is down to the maximum indicated of -32 c.I guess it does not have a conventional thermostat. Does anyone have any advice and how do I get into the electronics? we have done all the obvious things e.g. defrosting ,cleaning grilles etc.
beano 1939.

 

[wonkothesane]

Probably too late for the OP but may help someone else... I've just fixed an F7132S which has the same electronic module.

Note that the electronics is connected directly to the mains supply so remove the plug from the wall before you start!
The module is simple to remove: open the freezer door and under the module are three slots with catches - just push each in turn with a small screwdriver and pull the module gently forwards.

The power supply uses a 0.47uF 275V Class X2 capacitor which had gone low value so there was insufficient voltage to operate the relay. The compressor is connected to the normally closed relay contact so the freezer runs all the time.
For safety reasons it is critical that you only replace this capacitor with exactly the same specification component as you remove!

While I had the thing apart I also replaced two electrolytic capacitors in the power supply, a 100uF 50V and a 470uF 10V.

 

[beano1939]

Many thanks for that. I resolved the problem by taking the freezer to a local repairer. He removed the module and sent it to a specialist in Scotland .Don't know what they did,but it now works fine. cost was around £60,but it was worth it for an otherwise excellent freezer. If the problem reoccurs, then I will follow your advice.
beano1939.

 

[philipgreg]

Hi I've exactly the same problem with a 7132S, the relay does not operate so temp goes to -32. I've had the top off the relay and if I touch it with an insulated screwdriver it closes so I thought it was a faulty relay. What is the sign that the cap is faulty? I measured 10V across the coil so I thought it should have closed.

I was going to replace the relay but couldn't find the same part anywhere. Where did you source the capacitor?

If you are still monitoring these posts a reply would be appreciated.

Thanks

Phil

 

[wonkothesane]

If I remember correctly, it is a 24V relay - 10V is probably not enough to operate it.
I found a replacement capacitor from Maplin Electronics, part number N72CN at £1.74. It was a bit of a tight fit for height but it did go in ok.

 

[philipgreg]

THanks a lot I'll give that a go.

Phil

 

[philipgreg]

I performed the repair, replacing all 3 capacitors, took less than 10 mins and now the freezer works properly again. Thanks so much for the info. It cost me just over £2 to fix, if I'd called Miele out it would have been £98 for the engineer and £70 for a replacement circuit board!

This repair is well within the scope of anyone with average soldering capabilities.

 

[Thenan]

Hi,

I also have this problem with a Miele 7132.
What spec did you use for the other 2 caps?

Cheers

 

[philipgreg]

Hi

I ordered all my stuff from rapidonline.com

100U 63V 105 DEG.RADIAL ELECT (RC)
470U 16V 105 DEG.RADIAL ELECT. (RC)
17p and 15p!

They were slightly higher max voltages than the original but that's fine as the capacitance is the same

 

[TOMHEX]

Liebherr Freezer Model GS1583 (same as Miele model F 3410S-6)

FAULT: Often colder than -18degC with pump running continuously. Pump could be stopped by gentle knock on top of case just above control panel.

At first suspected bad soldered joint but after re-soldering 3 suspect joints there was no difference.

After reading this forum (MANY THANKS to everyone on the forum page before me – you pointed me in the right direction) I measured voltage across relay coil which was 11.6V – this was not enough to pull in relay armature but by knocking as above it did pull in and the pump switched off. The thermistor and temperature comparison circuitry was obviously working as the relay armature came out when the temperature had warmed up enough and pump restarted. Also traced out most of circuit on relay board and the 0.47uF is acting as a capacitive voltage dropper – rather in the manner of a series dropper resistor but without the resultant waste heat. If it loses capacitance then it's capacitive reactance increases and hence more voltage will be dropped across it resulting in less across the relay. This would appear to have happened in this case.

Replaced 100uF 50V with 100uF 63V 105deg but no change.

Replaced 0.47uF 275Vac X2 with same type of capacitor. FAULT NOW CURED.

Out of interest I tested the 2 capacitors which I had removed using a home built 1000ohm/V test meter on ohms range. Observed charging 'kick' of needle compared with that using new capacitor of same size. The old 100uF was identical in this crude test when compared with the new one.
However the old 0.47uF appeared to have less capacitance than a new specimen of the same type.

Finally the following voltages were measured which may be helpful when fault-finding.

With FAULT REPAIRED :-

Volts across 100uF - Pump on 16.6V Pump off 41.1V

Volts across relay - Pump on 0.16V Pump off 25.5V

When fault was present there was never more than 19.2V across 100uF nor was there more than 11.6V across relay coil.

Convenient measuring points are :-

Relay coil across glass diode near front of board adjacent to transistor and 0.47uF.

Voltage across 100uF - measure across 4 x 1N4000 bridge output.

NB. THIS CIRCUIT IS AT MAINS VOLTAGE - BE VERY CAREFUL - ALSO DO NOT USE EARTHED TEST EQUIPMENT.

Parts were ordered from www.esr.co.uk

I hope that this info is of help to someone.

 

[dungspreader]

I fixed a similar issue with a liebherr comfort fridge freezer (with dual compressors) by replacing the same .47uF X2 capacitor (which now costs £1.91 from maplin, still a bargain to keep fridge going). The board designs must share a common power supply.

Symptoms :

* Fridge light worked intermittently, then stopped
* Fridge temperature rose, got mouldy
* Freezer got colder & colder

I can only presume that the relays for the light & fridge are normally off and the freezer normally on - this explains the symptoms in the event of the power supply failing so the relays can no longer switch. I also found that knocking the top of the unit where the control board is caused the light to come on. I initially presumed this was something to with a magnetic reed switch that had become magnetized but the sensor is of the Hall effect type and the knock was causing the relay to switch on.

The control board was also resetting itself frequently (all lights out then flashing the red alarm light 3 times). This could often be provoked by pressing the fast freeze button.

Hope this helps someone else with a similar problem. This thread was hard to find!

liebherr comfort fridge freezer light broken not working fridge warm freezer cold

 

[paulgerrard1]

[thanks . Miele wanted £110 call out and £35 plus vat to replace the circuit board. Went to Maplins and spent £2.78 spent 5 minutes replacing the capacitors--BINGO fixed. Thanks very much for post.

 

[speakerman]

Hi, Wondering if anyone can help please!

I recently bought a Miele fridge / freezer secondhand as could'nt afford new, its been working really well for the last couple of months up until two days ago when I noticed my fav ice cream has turned to concrete with excessive cold and the fridge is warming up with the motor not turning off (and has a very slight "unhappy" noise).

Looking at your posts here I would say it sounds a very similar problem and have also found this fault on several appliances recently, my question would be is: although your faults are related to single freezer models could this also apply to the circuit board on mine?

I would really appreciate your help as I've waited for six months to get a fridge / freezer and just got used to having it now its gone pear shaped, the option of employing Miele to repair is a none starter!

Many thanks!

David

 

[Baker Steve]

This all sounds very much like a problem I have with a Miele freezer (an F-7462) - compressor not switching off even when appliance is turned off on control panel, and temperatures dropping to -32C.

Does anyone here know how to access the electronics module in an F-7462?

With thanks

 

[RichardMNZ]

Open the door and look up. Are there two screws on the left and right under the control panel?