Ariston Margherita timer stops by itself prematurely

[Carlos]

I have been repairing plenty of home appliances for my family and now that I have fixed most of the necessary ones I was asked to revive a marriage (or before-marriage) memento washing machine.

The model is Ariston Margherita AR 525 T. It was bought 27 years ago in 1987 and served them well until the timer/program knob started stopping on it's own on the first program. The owners were forced to go there manually to push the knob pass that point so that the rest of the program could continue. At a later time a second point in the program started doing the same, so now they had to go there twice. This is what I was told, they didn't have the time for me to run the machine and see for myself exactly what was going on. Perhaps this week I will manage to do just that when they have more free time.

As you can understand this became very problematic for them so they decided to buy a new one and saved the old one. I don't know when they stopped using it but I will assume it was at least 8 years ago (since the new machine is more or less that age).

I thought, by the premature description of the owner, that it was a fault with the timer, so I took the timer off quickly so that I could test it at home.

It is an elbi timer, type 100 T 85 and the serial/part number is (I think) 1008/0/2.03

I have checked the connections for the copper tongues continuity and (although there are a bit of soot/burn marks) not one fault was found. I have still yet to check if there are plastic indentions that got worn off and as such are not making the connection they should when the gears turn, but so far none of them seem to be like that visually.

I have also checked the timing motor and it doesn't look faulty. No chockes when I move it by hand, no smell and no burn marks.

I tried to get a hold of a connections diagram and the spare part list for a better analysis since I don't have the machine with me but the only thing that I managed to find was just the user manual.

What I would like to know is if any of you knows what might be the problem. Could it be that another part external to the timer is faulty and causes the premature stop during the program? Or is it indeed a timer fault and I am not doing the correct troubleshooting? Or perhaps something else that I didn't even consider, such as clogged filter?

I hope someone can help me with this, this forum looks amazing and the people in here have provided very interesting helps that served me in the past quite a few times so today I decided to join in.

I will link to the album containing the photos of the timer details and the manual frontpage because this forum only allows 1 and also small picture upload. This way you are able to observe more pictures, bigger and I won't take space of the forums, hope this is ok.

The website I used is having some trouble with loading the pictures but hopefully it will fix soon, if not I will re-upload them somewhere else:

 

[Carlos]

I have finished testing every configuration the cams allowed (360º rotation) individually and all of them check out good. I am now practically certain that the fault lies with another component but I don't know when I will have access to the appliance again so I am trying to figure out what the most likely possibilities are so I can take most ouf ot the time I have and go right to what might be the problem.

According to the owner's, the first time the problem started started was with the first program. I am reading here and I see that it contains the following program sequence: Dirty whites (cotton, linen, hemp)

- Pre-wash at 40ºC

- Wash at 90ºC

- Rinse

- Medium spinning

- Final prolonged spinning

Will try to do a test run next time and see exactly at which part it stops. Would love for the problem to lie simply with a capacitor (it has a big one) or a thermostat since it would be far simplier to fix/replace.

 

[hotpoint9534]

I agree, it would help to know exactly where in the programme the timer stops. If it stops in the wash segments then the heater element might be broken. This timer doesn't seem to have a thermostop device (solenoid) attached, so it is likely the timer is supposed to stop until a certain temperature is reached.

Tom

 

[fido]

Usually when the timer goes through most stages but gets stuck at one or two places it is either a fault in the heating circuit (element or thermostats) or the filling (electric water solenoid). If, for example, the solenoid coil for the fabric conditioner rinse burns out it will get stuck on the final rinse. A rarer fault would be failure of one of the water level switches in the pressure switch. I'm not familiar with that model but it may be one that was not sold in UK.

 

[Carlos]

I have managed to do a test run today and the possibility of the problem being related to either the heating element or thermostat is now strong.

I have let the machine run the program and waited for it to stop prematurely on its own. Once it stopped I waited for around 10 mins, hoping that maybe it was just waiting for the water to heat. After that I decided to turn off the temperature setting, the machine instantly resumed the program and ceased when I turned the temperature back on.

Bypassing that point by moving the program furhter manually allows the machine to continue. This is what the owner of the machine was explaining to me and it was easily replicated.

I will try to run a voltmeter continuity test on the heating element tomorrow, thermal cutout and - if it shows to be functioning properly - test the thermostat as well.

Is there any other component that might be related to the heating system that I might be overlooking?

By the way, I took a picture of the machine running the program without the top on if anyone is interested. It is an Italy model.
If anyone is interested in other views just ask and I will try to take them.

 

[fido]

The other part of the heating circuit is the pressure switch. Normally when the wash water level is reached, the water solenoid turns off and the heater safety cut-out is over-ridden, to enable the heater circuit to go on (when also selected by the timer). Obviously it would be dangerous for the heater to come on with no water in the tub.

 

[Carlos]

Hi, fido, thanks for the heads up. I wouldn't remember to check for that one as well, it makes sense that it might also be causing the problem seeing that -as you said- the heater wouldn't engage if there was no water.

I will check it in 2 days and hopefully by then I will have found the problem(s). Thanks again, fido!

 

[Carlos]

I am sorry for adding a second reply to the last one, but I remembered something. If the pressure switch was faulty, wouldn't the machine overfill? Seeing that this switch is the one responsible for the water level, if it was faulty it would also cause problems when the water fills, which it didn't. Am I thinking about this the wrong way or am I correct?

 

[gizmo]

Pressure switch - it could get complicated. It would all depend on the specific wiring of this model. It can be a multi-level pressure switch, where the terminals controlling water inlet are separately switched from the ones that control heater function.

But I would not bother checking pressure switch yet. My money is on heater element or wiring to the heater. I have never seen a faulty thermostat though they must exist. I have seen a small number of failed heating elements but the first thing I would check is the wiring - burned terminals, snapped off heater terminals, wire broken inside the plastic insulation - that is quite common where the wires attach to the heating element. With the normal bouncing around on spin, the wires to the heating element have to do a lot of flexing. Copper becomes weak and brittle after years of such flexing, and can snap inside the plastic insulation. The wire looks undamaged from outside - sometimes you can see a tiny heat damage at the point of the break but the best thing to do is (WITH THE POWER DISCONNECTED) feel and flex the wires near the heating element, if there is a hidden break the wire will bend more easily at one tiny spot. It often occurs right at the terminal, so the cure is to snip off the terminal and fit a new one at the site of the break.

 

[fido]

The contacts in question on the pressure switch are what's called a changeover switch, the power is switched from the water solenoid to the heater circuit. It would be possible for the actual mechanical movement of the contacts to still be working so that the water still switched off but for there to be some burning of the contacts, meaning that they could no longer pass the higher current required by the heater.

 

[Carlos]

Ahh I see, I will then check for the primary heating components first and if I don't find any problems with those I will also check the pressure switch.

Don't worry, I don't test electrical components when the machine is still plugged to the wall, I am not that experienced yet to do such thing. With some luck I will be able to check the machine tomorrow. The rust concentration in the back-bottom of the machine might be a good indicator of components in that vertical path that might have been affected by rust as well, only by opening I will be able to confirm this. I just hope that this isn't a sign of a faulty seal or something else causing a leak from the tub.

I will also try to remember to take pictures of the problem(s), if I find it. Thank you all for the support you have been giving.