Sunbeam EM6910 ,playing up!

[mulquemi]

Hello coffee loving people,
Now I should be able to fault find this machine's problems however,I'm presently not in the ideal place to do that on this occasion.
This machine has arrived and it's 's history is this:
Machine would leak all over the bench when turned on,sorted!
Silicone hose to main pump was fractured just below the zip cable tie,I readjusted the bend of the hose and trimmed excess and re-secured the hose.
The main problem is machine will begin to heat up and then unexpectedly short out the circuit breaker.
At this point there is no water causing this short that I can identify,I wish to pick the collective brains as to what should I look at first,as possible reason?
I have another machine that will serve as components to exchange parts to eventually locate the source however,in an attempt to quickly locate the troublesome cause,what would the first suggestion be to check?
All helpful assistance is most appreciated,thank you.
Kind Regards,
Mick.

[TampIt]

G'day Mick

My first steps for any machine with that issue are
1) out with the multimeter & look for shorts or unusual resistance values - usually the latter from your symptoms. Wriggling the parts at the time may help identify the culprit.
2) Spray everything in sight with circuit cleaner - does the behaviour change?
After that, onto the bench and start tearing it down.

Good luck.

TampIt

[Xanthine]

Hi Mick
Not sure if it is taking out the earth leakage breaker or the normal breaker. If it is earth leakage it could just be due to condensation - you could try drying the machine out for an hour or two in a hot car sitting in the sun or with a hair dryer then re-trying. The heating elements in all these machines, by their nature, tend to leak current to earth and the condensation in the machine could be just taking it over the edge.
Trev

[mulquemi]

TampIt and Xanthine,
Thanks for you prompt input,yes to the earth leakage tripping rather then over current,I'll open the case right up and go through as per your advice,thanks again.
I have a spare circuit board which I can use as replacement to eliminate the possibility of failing circuit components (TampIt).
Cheers,
Mick

[sprezzatura]

If you have an insulation tester you can quickly check the water solenoid coil and the two coils that run the steam and water pumps. Intermittent fails trip the RCD even if the ohm meter registers acceptable resistance.

[Xanthine]

Just watch out for the pump coils. They have inbuilt diodes in series with the coil - not sure what their max reverse voltage is but 1000v setting on megger may be too much if put across the terminals.
They are also a trap when measuring their continuity as they show o/c in one direction or odd readings with some DVMs on resistance ranges. Best to use the diode test setting on DVM (for continuity not leakage!)

[sprezzatura]

Good point! I set my Megger on 250v for a sustained test although I've yet to fry one at 500v for long enough to obtain a reading.

[sprezzatura]

The Ulkas have a terminal that depicts diode direction on the male spade terminal: I'll take an image of a spare I have on the bench.

[mulquemi]

sprezzatura/Xanthine,
Thanks for the hint,my megger too has the 250/500/1000 volt range,I'll be careful not to fry any coils, I too have seen the directional symbols on the pumps,most important.
Its great to have such competent advisors on hand,many thanks.
cheers,
mick.

[sprezzatura]

Here's the water pump forward bias measurement. Switch leads to get a OL (hopefully)

[gruntguru]

My 6910 was doing the same thing. Traced it to a fractured solenoid valve.

[mulquemi]

gruntguru,
Interesting challenge it was too,turned out to be a fractured tube liner of the solenoid in three way valve which then appears to have directed excessive pressure to the steam pump,this resulted in distorting the plastic body of the UKLA steam pump,allowing water to pour into the base of the machine.
Replaced both the complete three way assembly together with the steam pump.(both from functioning second hand machines).
No leaks and or shorting now,with the result owner is again, happy and contented.
Cheers,
Mick.

[mulquemi]

Hello again,
Now I will need some additional (operational) replacement parts to return my donor em6910 to fully operational condition.
As seen in the attached image,steam pump plastic body has been deformed to the point of serious leakage and solenoid liner was found to be fractured,I haven't seen that happen before.
Parts required are both items,so what do you think you could assist me with?
Very happy to pay general postage to 3690 for these parts,most appreciated if someone has these available.
Cheers,
Mick.

[noidle22]

I can supply these but unfortunately I can't do it cheap as the parts will be brand new. Send me a message if you are interested and I'll see what sort of deal I can do.

I had a 6910 in store today with this problem, it's very common and also dangerous as well as causing damage to other components usually.

[mulquemi]

noidle22,
Thank you for kind offer however,playing with espresso machines in more of a leisure activity for me,having purchased ,on one occasion,five (four em6910's one em6900) of these machines for $80.00 of which you received the only non viable corpse (in bits).
My present machine had to donate it's two missing parts to allow a collegue's machine to live again,successfully.
I am very grateful for your offer however,I will probably go the E or Gum way again and pick another sunbeam (or two) at a price too good to refuse.
Kind regards,
And Cheers,
Mick,