Smeg SUK62MFX5 – Oven fault (will not heat)

[Garyu]

My Smeg SUK62MFX5 has worked satisfactorily for about 2yrs. It has now developed a fault where the oven will not heat/operate. When I turn it on, the fan starts, the internal oven light comes on as normal but the orange neon (to indicate it is heating) stays off.

I’ve stripped the rear casing off the unit, checked as many connections as I can to no avail.

Any ideas please? Any knowledge of any common faults on this cooker?

Thank you very much
Gary

[Penguin45]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Fan oven element. Drop like flies. Hundreds of posts, everywhere on the site.

Element is p/no 806890449 – an email to spares@ukwhitegoods.co.uk will get one moving for you.

Power off when investigating/fitting.

Regards,
Penguin45.

[petalpop]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

not doubting your superb knolledge but surely the fact the neon isn`t coming on would point to it being the t/stat
8)

[gegsy]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Im sure it would 😀

Greg

[Garyu]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Thanks for the 3 replies (very much appreciated) – I guess from these it could either be the fan oven element or thermostat. I’ll measure the resistance of the element and also try to check for voltage on either side of it when I turn the oven on (I am a Computer Engineer by trade so all will be safe)

The main point for me is the neon – it doesn’t light at all when I switch the oven on, I do know that when the oven is working perfectly, the neon goes out when the oven is hot enough and then comes back on etc as normal when heat is required to keep it at the required temperature…..

I’ll post my findings over the next couple of days – but if anyone would like to help me on the measurements it would be very useful…e.g.,

* What is the likely resistance of a good/working element?
* With one probe on earth what voltage would I expect to see on either side of the element when I switch on as though I’ve asked it to heat?

Thanks very much 🙂
Gary

[gegsy]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Garyu wrote:
* What is the likely resistance of a good/working element?

Around 30 ohms

* With one probe on earth what voltage would I expect to see on either side of the element when I switch on as though I’ve asked it to heat?

We don’t recommend live testing on any appliance. Your ability may be fine but other viewers of this forum may not have the same capability.

As the Penguin mentioned, it could quite easily be the element that has gone and blown the neon and/or thermostat.

Power off before investigating please :zap:

Greg

[Garyu]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Thanks Greg, I appreciate your last comments.

I spent most of this morning working on the oven, now I have good news and bad news.

The GOOD news is that I found a fault and the oven now works. The oven element measured 20ohms resistance, I then set about checking the thermostat/oven switch. I found a very loose spade connector on the thermostat…both the spade and the actual connector on the stat were heavily tarnished probably because of heat with the poor (very bad) connection – the spade connector literally slid on/slid off with no real effort. So – I cleaned the connector on the stat and replaced the spade connector – after doing this the oven worked fine, it heats up, switches off when the stat stops calling for heat and then switches back on when the stat starts calling – so GREAT!

But the BAD news is the unit will only work absolutely fine at low’ish temperatures. If I use it at say 200oC the oven will heat, the neon goes off when 200oC arrives, then when the stat calls to keep the temperature up the whole unit shuts down after about 2min of further heating – the clock/timer turns off and only the cooling fan (not the oven fan) stays running.
I guess the unit is now overheating? If I leave the unit to cool, it powers back up itself after about 15mins (obviously much cooler)

I wondered after my good fortune with the original symptom if anyone had any further suggestions? I did notice whilst inside the unit (with the power off at all times) there were a few temperature sensors (thermistors?) dotted around the chassis.

Any ideas anyone – any help, much appreciated

Gary

[gegsy]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Does the cooling fan come on, blowing above the door of the oven, say after 10 mins?

Greg

[Garyu]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

I’ll check that tonight Greg….please standby – and thanks!

[Garyu]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Evening Greg,

The main oven doesn’t have a cooling fan only it’s main fan inside the circular element, it has a small hole (the size of an old half-penny) at the back which feeds an exhaust type shoot which screws to the rear casing – I can’t find a fan. There is a cylinder type fan on the upper oven/grill which DOES switch on after about 10mins, it blows air up upwards out of the top of the cooker unit.

Earlier, I took the rear cover off, reseted all temperature sensor connectors and let the unit run on maximum 245oC…..I made the area safe, nothing was touched inside the unit. The unit ran consistently for 45mins at maximum temperature – no faults, remember the rear over was off. I then turned it off to let it cool.

I’ve just put the rear cover back on and then switched on. I ran the unit upto say 230oC and it then cut-out as it did before. The timer display went blank, the upper fan stays spinning and warm air is being expelled from the top grille.

So do you think something is on the verge of reading a temperature fault? The original fault of no heat at all seems to have been fixed, the stat is switching as expected – I’m now left with this suspect overheating issue.

I can’t see any other fan that should be spinning to keep the chassis area cooler where the sensors are.

In fact as I type, the unit has cooled sufficiently that it has ‘clicked’ and the LCD is now flashing – the unit will now work again.

Any ideas Greg?…..thanks for your help

Gary

[gegsy]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Sounds like a faulty thermal cut out TBH.

Greg

[Garyu]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Evening Greg,

Sorry it’s been a short while since my last message……slowly but surely I’ve been trying to identify which thermal cut-out has been causing the shutdown….it turns out, having bought an ‘oven thermometer’ from a hardware store that the Smeg is ACTUALLY overheating and the thermal-cut out responsible for the shutdown seems to be working OK.

I therefore think after the original fault at the top of this thread there has been damage caused to the thermostat (which I hoped I’d get away with 😥 ).

Now, when the unit is set at 50oC the oven heats to 200oC – leave it at that temperature and the Smeg will stay around 200. This of course is OK until my wife wants to cook a rice pudding at 100oC 🙁

So it looks like I need to replace the thermostat, could you therefore please tell me:

* If on the face of my comments above, you agree with me?
* I take it a replacement thermostat will comprise of the actual switch and knob assembly + the long wire to the probe in the oven itself?…will that be part of the stat itself?
* If I can buy one from you guys or your preferred supplier – just need the partcode if you don’t mind and I can call/email them – any ideas how £much to expect this will cost?

Thanks again for your assistance
Gary

[Penguin45]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Hi Gary,
Diagnosis completely reasonable……….
Main oven stat is p/no 818730401 – no idea of price on a Sunday. The item supplied is the switch unit, gas capillary and probe – you will need to recover the knob for re-use.

An email to http://www.spares@ukwhitegoods.co.uk will get things moving for you.

Regards,
Penguin45.

[Garyu]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

Thanks Penguin45,

I’ve sent an email to the address you state above…..just one thing though, I’ve found a picture of the Smeg partcode you mentioned above – mine is completely different?…

…the part I require is much longer, more spade connections, mostly black in colour and the thermostat in encased in a black plastic shroud.

Would you mind checking the partcode please Penguin?

Many Thanks – again….
Gary

[Penguin45]

Re: Smeg SUK62MFX5 – Oven fault (will not heat)

I suspect you’re describing the spark ignition unit…… P/no I listed is defo stated “Thermostat”.

Penguin45.

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