CF 350 no longer heats up

Dear forum participants, I ask for your help in solving my problem.
After a half year break I have taken my old AEG CF350 in
operation again today. I was immediately "prompted" to decalcify the machine.
Decalcification takes place in 14 steps, the sequence of the individual steps took considerably longer than I had remembered. From step 7 the engine has properly overheated, at step 9 the steam pressure has been so high that the
steam nozzle has been pushed out of the holder with a loud bang.
Then it has calmed down again. Decalcification has been properly completed. I've shut down the machine.
The routine started to run normally when the device was put into operation again, only the message "device heats" would still light up if I hadn't switched off the device after 15 minutes...

What could have happened ? Where should I start the troubleshooting ?

To this end I would like to mention that I am ambitious, but have almost no idea of electrics/electronics !

Best regards from Austria
Roland

Hi,

According to the description the thermostat and the fuse should be defective. If you are unlucky, maybe the thermoblock is broken too.

Greeting
Stefan

As I said, I am ambitious, but a technical "Nackerbatzerl" as they say in Austria.

Thermoblock and thermal fuse I recognize, but where is the thermostat and what does it look like ? How do I recognize that the parts are defective or which could be defective ?

Beauty greetings from Austria
Roland

I assume that the machine has overheated...
Normally only the thermal fuse blows.
How you can clarify this exactly is described here.

Then it would be interesting why the machine has overheated. If you had accidentally dismantled the thermosensor (white plastic part with two thin red cables)?
If it is not properly attached (with heat conducting paste) it could come to overheating. The same applies if the plugs on the control panel are not plugged in correctly.

Gruß Joranz

Since I don't have any measuring instruments it always takes a while...

I noticed during the measurement that both the blue and the brown fuse (Sefuse SF 152E 157° resp. SF 169E 172°) might be defective (no electrical continuity).

I ordered both fuses on Ebay. Since these will be delivered in the next days, I have looked at how to change the two cables.
The first part of the exercise - removing the cable lug - is not too difficult. But how do I get to the connector where the other two ends of the fuses are clamped/screwed ? Do I have to remove the whole plate on which the pump/motor/spindle is fixed (is that possible at all ?)?

As I had to loosen the fixation of the cables or the sensor on the thermoblock, I noticed that the sensor has detached from the block. Is it enough if the sensor is mechanically fixed again or do I have to glue it with a thermo paste ?

Beauty greetings
Roland

So far, I've just gotten the thermal fuses from the electronics store around the corner. These things cost about 1 Euro... Then I took off the old fuse at the cable (with some force it works already) and clamped the new fuse with the corresponding clamps. So I never got the embarrassment to change the whole cable, which might be quite expensive. Leave the cable inside and just change the fuse. With some skill you should be able to use the old terminals again.

The thermosensor does not have to be glued on, but there should be some thermal paste in between to ensure a reasonable contact! If the thermal paste is missing the fuses will probably blow again right away.

Greß Joranz

This variant - changing the fuse - I also thought about, but I assumed "worst case", because removing the fuse from these clamping sleeves (where are these things available at all) did not seem possible to me. I bought myself some fuses now, too.
I assume that they are probably suitable for this purpose, but the maximum allowable temperature is different from that of the blown fuses. 152° instead of 157° or 167° instead of 172° - so the fuse would already give up at a lower temperature...

Is this permissible/sensible/practical if I install this similar fuse ? Or must the "fuse temperatures" of the defective and the new fuse be identical ?

Beauty greetings from Austria
Roland

If necessary you can still cut off the old fuse and strip 3mm cable, that's how much reserve you have there...
I got these crimp sleeves together with the fuses in the electronics shop.
Fuses that respond a few degrees earlier are definitely not a problem. But of course the triggering temperature should not be higher.

Had you already measured the thermoblock, if the cable is still ok?
Disengage the cable and measure the resistance between the two connections. Should be somewhere in the range of 45-55 Ohm...

Greeting Joranz

The resistance of the thermoblock was measured. 45 Ohm - I assume that the thermoblock is not defective. I replaced the "157er" thermal fuse by "152" (in Austria there are apparently no 157er"), lubricated the thermosensor with thermal paste, screwed the machine together and.................it heats again !!

Joranz I thank you for your help !

Best regards from the country where there are obviously no 157° or 172° thermal fuses !

Roland

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