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AEG Oko Lavamat 610 Electronic, E-Nr. 605 637 203. Bought new about 15 years ago but it failed after about a year, then was put into storage (in 2002) because we were moving house. Just got it out of storage to see if I can fix it because the one we picked up temporarily after the move has just died too.
In this post Penguin65 says he thinks that this is a good old machine, so I think it’s worth putting a bit of effort into it.
The symptoms are that on all wash programmes the machine fills with water properly (to different levels depending on the programme) but then sits there without rotating the drum to wash. On the spin programmes it rotates the drum sowly (in both directions) and also spins at high speeds, all as expected.
I’ve taken the timer unit out and can’t see anything obviously wrong. The little sychronous motor runs OK, and while a programme is running the timer unit makes the usual clicking and whirring noises.
I’m fairly sure that the timer will be obsolete/unavailable but it looks as if it will be pretty straightforward to dismantle so I plan to do that next, but before I do I thought it might be worth asking here if there’s anyone who can give me an idea of the way the thing operates.
There are two distinct parts to the timer unit, the first part is the electronics assembly. This can be unplugged from the second part, which is the motor driven thing containing (I presume) contacts which switch the valves and motors on and off. This block of contacts is fitted on the shaft which is turned by the programme knob.
As the machine will spin I’m fairly sure that the electronics assembly is OK and that the problem is something like a pair of dodgy contacts in the block on the programme knob shaft.
I’m guessing that some contacts make the motor run on a spin cycle, and some other contacts make it run when it washes. If anyone can tell me which set or sets of contacts would be responsible for instructing the motor to run when it washes, I’d be most grateful. If my wild guesses are completely wrong and it isn’t like that at all, that would be useful information too.
I’m a chartered electrical engineer but it’s a long time since I’ve given myself a 240Vac shock. 🙂
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
Once it fills with water on a wash cycle it stops to heat the water. If you were to turn the thermostat to cold at that point only then it should begin to tumble normally.
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
Martin wrote:Once it fills with water on a wash cycle it stops to heat the water. If you were to turn the thermostat to cold at that point only then it should begin to tumble normally.
Thanks very much for taking the time to reply.
Yes, of course I know that the machine might need to heat the water, and perhaps I should have explained that obviously I have the thermostat set to cold when I’m testing it.
But it doesn’t turn the drum to wash, hence my questions.
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
jubilee wrote:
Martin wrote:
Once it fills with water on a wash cycle it stops to heat the water. If you were to turn the thermostat to cold at that point only then it should begin to tumble normally.Thanks very much for taking the time to reply.
Yes, of course I know that the machine might need to heat the water, and perhaps I should have explained that obviously I have the thermostat set to cold when I’m testing it.
But it doesn’t turn the drum to wash, hence my questions.
Come to think of it, another explanation for the fault might be that whatever is supposed to tell the machine that the water is up to temperature is not getting its message through to whatever is supposed to be listening. Or that whatever is supposed to be listening, isn’t.
The thermostat does click, at more or less the expected temperature, as you turn the temperature setting through its range. The heater relay also clicks, so the thermostat and at least some of its wiring is working.
HTH.
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
QUICK FIX wrote:brushes
The machine has done about a year of service.
It tumbles and spins fine on the spin programmes.
Can you explain why you think it might be the brushes?
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
What happens if you put it on a rinse and spin cycle? Will it tumble OK on rinse?
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
Martin wrote:What happens if you put it on a rinse and spin cycle? Will it tumble OK on rinse?
Yes, see the third paragraph of my original post.
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
check the module at back of the timer for dry joints also check the switch bank at the front for good connections
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
QUICK FIX wrote:check the module at back of the timer for dry joints also check the switch bank at the front for good connections
Thanks, will do. Might not be until the weekend, work’s getting in the way, but I’ll report whatever I find here.
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
jubilee wrote:
QUICK FIX wrote:
check the module at back of the timer for dry joints also check the switch bank at the front for good connectionsThanks, will do. Might not be until the weekend, work’s getting in the way, but I’ll report whatever I find here.
Checked the switch bank and its connections to the timer, all OK. Even ran a wash cycle (programme 3 with rinse hold) and it held at the right place until I released the hold. In fact it did everything right except for the part where the drum is supposed to go round when there’s water in it. 🙁
Checked that there were connections made and broken by the timer on most of its contacts. Found no obvious evidence that there’s anything wrong with the contacts, but I don’t find it easy to fathom out on that thing what’s supposed to happen when, so it isn’t yet ruled out.
Checked the joints on the board at the back of the timer, and they all look well made. There’s some discoloration from heat around the ballast resistor as you’d expect, but the passive components in that area all seem to check out fine. The board doesn’t look like it’s ever been wet. Near the relay there’s a row of four small holes through the board, a couple of which pierce copper tracks in places which look like they shouldn’t have piercings. Looks like a CNC accident or something, and looks like it was done after the solder resist was applied. AFAICT there’s no harm done, the tracks aren’t cut right through but there’s a good 50{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the copper lost. Can you tell I’ve done this sort of thing before?
However… I decided to get down and dirty with a multi-meter on all the components on the board, so I pulled it and got to it and I think I might have come up with something. There may be one or two dead transistors on the board. Can’t be sure yet because I’m testing them in situ (well, not exactly testing them, more of a wheel-tapping exercise) with what is basically a diode tester. If they’re bipolar transistors and not FETs then at least one of the transistors seems to have an open circuit junction.
That’s the good news, if there is any good news in this story.
The bad news is that (a) the transistors are surface mount devices and (b) I can’t identify any of them. Some of them are marked “G1F”, some are marked “G3F”, and some, if they’re marked at all, are going to need a microscope. The one that I’m almost sure is dead is marked “G3F”.
Before I get the microscope out, can anyone help me with the ID of these components? If dead transistors is the problem, then I can probably find near equivalents which will do the job that aren’t surface mount, and solder them in place of the failed ones. There’s going to be nothing very critical about the characteristics needed, it’s not like it’s taking samples of rocks on Mars.
Re: OKO Lavamat 610 Electronic fills empties spins doesn’t w
Well it’s gone very quiet here, but I haven’t been idle. I found the fault and fixed it, and the machine is now working perfectly.
After a fruitless week of looking for obvious problems I decided that a more structured approach was called for. So I traced out the entire circuit of the washing machine on several sheets of A2 paper. I also managed to find a PDF for the “LAVAMAT_610” online, which helped enormously although it has quite a few errors and doesn’t seem to be for exactly the same machine as the one I’m working on. One very useful bit of information in this document was the functions of, and timings for, the contact pairs on the electro-mechanical timer.
I dismantled the machine completely, including removing the electro-mechanical timer from its circuit board. So that I’d have a record of it later, I photographed both sides of the board. While the timer was out I tested its operation and found that as far as I could tell it was working perfectly.
I tested every component in the machine as best I could while it was in pieces. I could find no fault while the machine was not powered, so I rebuilt it and started tests while it was powered up. Don’t do this at home, boys and girls.
The motor speed control circuit board (AKO Typ EE 100) is attached by a couple of connectors (5-pin and 6-pin) to the printed circuit board which carries the electro-mechanical timer.
There is a 20-pin integrated circuit (IC) on the speed control board which does things like phase-controlled triggering of the triac which drives the main motor for wash and spin, and it also has some logic to decide whether a spin or wash is permitted — in case, for example in some fault scenario, the machine should try to spin when the drum is full of water or wash when it isn’t. By measuring the inputs levels to this IC I determined that the input to pin 7 was always HI (+5V referenced to ground) and reading the circuit diagram which I had traced out, at some stages during the wash cycles I would have expected it to go LO (0V referenced to ground).
So I grounded it. (see note at * below)
Lo and behold the machine would now wash, but not spin. Progress. 🙂 This narrowed the fault down to about a dozen components between the heater relay and pin 7 of the IC. Previously I had tested all these components with no power applied to the machine, so now it was time to measure the voltages on them during operation. Please remember that bit about not doing this at home.
Unluckily most of these components are (a) difficult to get at when the machine is operating (b) near another, very hot component and (c) floating around at 240V. So live measurements were a bit tricky but I eventually managed to make those that were needed.
One measurement turned out to be especially interesting. Instead of the roughly 60V (RMS half-wave rectified AC) that I expected at the junction between a 100 kilohm resistor identified as R11 on the speed controller circuit board and the next in the circuit, I was seeing about 100V. At this point the fault was very obviously in the resistor, despite its having checked out OK previously in more than one cold test. What a nuisance. At least I think that’s what I said.
The faulty component was in the part of the discrete component circuitry which tells the IC that it can either wash or spin (because, respectively, either the drum contains water or it doesn’t) and unfortunately the fault resulted in faulty logic. The IC was being told that the drum was always empty, so consequently it would only allow a spin-tumble or a spin, never a wash.
The reason for the fault was basically cheap construction, particularly the use of a 3.6 kilohm ballast resistor (which dissipates around 10W in a fairly confined space) to drop 240Vac to something more useable by the electronics – 5V to 9V or thereabouts. In the process the ballast resistor gets very hot. While it might be capable of coping with the heat, some of the components around it are not rated for that kind of cooking and one of them, my 100 kilohm resistor, failed. After not many hours of service, I might add, very disappointing in an expensive product like the AEG OKO Lavamat 610.
It failed in an intriguing and very frustrating way. When it was cool it measured fine on a multi-meter. When it was hot it changed value from about 100 kilohm to anywhere between 500 kilohm and over 900 kilohm. In fact on one occasion after an extended cooling-off period the thing even worked for more than just a moment, briefly making me think that either my multi-meter was on the blink or I was going nuts.
I replaced the crappy little 0.25W carbon film resistor by a 0.4W metal film variety, saw 58V instead of over 100V where I was expecting about 60V, and the machine immediately came back to life.
Out of respect for the forum policies I won’t post links to the PDF file that I found online nor to my circuit diagrams, but if anyone wants to see them the please contact me online.
Thanks for the help guys.
Cheers,
Ged Haywood.
BSc (1st hons) C.Eng, MIET, MRIN.* Note: that ‘ground’ in this case is more nearly the 240VAC line. DO NOT ATTEMPT TO DO THIS KIND OF STUFF IF YOU DON’T FULLY UNDERSTAND THAT because at best the electronics will go up in a puff of smoke, and at worst there will be wider damage to property and people will get badly hurt.
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