Who's good with electronics?

PeteHall

Moderator
Not caving related, but since there seem to be a few folks out there good with lamp electronics, I wonder if anyone can help with this one...

So yesterday morning, the washing machine wouldn't drain, the pump tried, but wouldn't run. I removed the hose and drained it by gravity out the back door. I then turned the machine on its side to access the bottom panel, removed the pump and removed the offending lump of limescale that had blocked it. After thoroughly descaling the pump, I put it back together and gave it a test.

10s on the fill, then set it to drain, and the pump worked as it should.

Unfortunately, the display started flashing all over the place and beeping randomly... I switched it off quick.

Having now stripped the top of it, it seems that a drop of water dripped onto the circuit board when I put the machine on its side, as there is evidence of a tiny bit of water in a few places.

On closer inspection, there seems to be a little smoke residue centred on a small resistor or whatever it is.

If that component has got hot enough to smoke, I assume it will need replacing. Or might it still be ok? How would I test it?

Is the rest of the circuit board likely to be ok if I dry it thoroughly?

Thanks
 

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RobinGriffiths

Well-known member
The component in question is a diode D9. I assume the part number and the cathode marker have burnt away? Possibly the same part as D5 which appears to be a IN4007 general purpose diode. If it's smoking then either it's maximum current (1A) or voltage (1000V) have been exceeded, almost certainly the maximum current.

Water might have shorted the output to ground - not sure what the conductivity of water with detergents is, but I think there are some metallic ions, so there might well be a path to ground.

Alternativelly there might be be a short to ground in some component 'downstream' from the diode.

To just test the diode, put a multimeter to resistance mode. Connecting the probes to either side of the diode, you should get a low resistance with the probes one way round, high the other (assuming the multimeter pokes out enough voltage to exceed forward voltage drop:  0.6V). See what you get testing D5 and D9.

However, I would expect the smoky diode to be a symptom of the problem rather than the problem itself.
 

Fjell

Well-known member
If this is in your house it?s just not safe enough now if it were me. You will have overloaded a number of components, such as the transformer to the left maybe. That seems to be the power supply area.

You can buy new boards online for many machines, and it?s usually not too tricky to do like for like.

What you see on Ebay is the nasty ones (Hotpoint, talking about you) have the most spares for sale. Might be time to get a new Miele if that fails.
 

PeteHall

Moderator
Thanks guys.

RobinGriffiths said:
I assume the part number and the cathode marker have burnt away? Possibly the same part as D5 which appears to be a IN4007 general purpose diode.
I've just cleaned the area with a soft (dry) brush and everything looks fine; none of the paint has burnt off. And it is the same as the one next to it.

However, I would expect the smoky diode to be a symptom of the problem rather than the problem itself.
I suspect that you are right. My gut feeling was that something had shorted as it got wet, then burnt itself out. Once dry, the short should go away and perhaps replacing the diode will fix the remaining problem? We will see...

Fjell said:
You can buy new boards online for many machines, and it?s usually not too tricky to do like for like.
Unfortunately, this one is out of stock everywhere I can find that lists it.

Might be time to get a new Miele if that fails.
It'll take a bit more frustration and failed repairs before Mr. Cheapskate here buys a Miele! :eek:
 

Oceanrower

Active member
That?s not a resistor, that?s a diode. If you?ve a multimeter (or even a battery and a bulb) it?s easy enough to test. Plenty of videos on YouTube if you?re not sure.

ETA. That?ll teach me to read the thread instead of just replying. Covered much better above by Robin.
 

alastairgott

Well-known member
Don't kill yourself pete.  :blink:  might be worth making sure there's someone else in the house while you're doing all this tinkering, or just get an electrician out?
 

SamT

Moderator
My circuit board blew/shorted because it was covered in black dust that was actually the carbon/graphite dust off the brushes from the motor (which I'd not long since replaced).  the dust obviously gets blown around when on a fast spin, and it had coated everything in a find conductive layer of dust.  Obviously at some point, it had become thick enough to form a connection and shorted the circuit board. 

Ended up with a new washing machine as the circuit board seemed to just about as expensive as a whole new washing machine.
 

Fjell

Well-known member
PeteHall said:
Thanks guys.



Might be time to get a new Miele if that fails.
It'll take a bit more frustration and failed repairs before Mr. Cheapskate here buys a Miele! :eek:

Yeah, but. All notions of shared responsibility go out the window when it comes to a woman with kids and no washing machine. It?s going to be your fault. That hard stare will rapidly oppress you and have your skull in a vise. You then buy a Miele that lasts 20 years+, because what more could you do? You?ll just have to work harder to fund it.

They also wash rope with no complaint and we are well over 20 years with ours.

You really shouldn?t use one with a shorted power board, jokes aside. White goods fires are a massive problem. See ?Grenfell Tower?.
 

sinker

New member
Fjell said:
PeteHall said:
Thanks guys.



Might be time to get a new Miele if that fails.
It'll take a bit more frustration and failed repairs before Mr. Cheapskate here buys a Miele! :eek:

They also wash rope with no complaint and we are well over 20 years with ours.


OK so that's a cue to expand the thread into a discussion on the weirdest thing that you've ever put through a washing machine...

I'll open the bidding with "A wiring loom for a Mk2 Ford Escort".

I've also put the cylinder heads off a Moto Guzzi 850 LeMans though the dishwasher  :)

 

ChrisJC

Well-known member
sinker said:
I've also put the cylinder heads off a Moto Guzzi 850 LeMans though the dishwasher  :)

I've put no end of Land Rover engine and gearbox components in the dishwasher. With a good dose of Gunk or Jizer to help!

Works a treat.

Chris.
 

PeteHall

Moderator
Now the circuit board is thoroughly dried, the washing machine seems to be working as usual (without even replacing the diode), but I'll probably not leave it running while we are out of the house until I've got a bit more confidence that it's not going to spontaneously combust...

sinker said:
OK so that's a cue to expand the thread into a discussion on the weirdest thing that you've ever put through a washing machine...

or other domestic appliance?

I have been known to put suspension parts in the oven/ freezer, which works a treat if you haven't got a press. Top tip, clean thoroughly (see above) before putting any car components in the oven!  :eek:
 

Pitlamp

Well-known member
In case it does come down to forking out for a new washer, I bought a Bosch one about 16 years ago, from Tooby's at Ingleton. Not the cheapest but it's still running like a train (he said, firmly touching wood). I think you do get what you pay for.
 

SamT

Moderator
Ours was a bosch and we replaced with a bosch - I was impressed by the fact that things seemed easily fixable/replaceable.  e.g. the motor was easily removed (2 big bolts) and the brushes easily accessed to replace (available from ebay).

So many items are just covered in plastic clips and proprietary fixing, that are impossible to figure out/undo without usually breaking something.  :mad:
 

Pegasus

Administrator
Staff member
I fixed the tea towel holder rail today by tightening a screw - just waiting for the washing machine to blow up and I'll have a go at fixing that too  ;)
 

Mr Dinwiddy

Member
I once saw a recipe for dishwasher chicken. You wrapped it in foil and put it on the hottest wash with no detergent tablet. I didn't try it but I liked the idea.
 

royfellows

Well-known member
As general comment on washing machines, the Calgon adds are not BS.
My Bosh played up a few years back, see how long they last, and it appeared that the water level indicator or indicators were malfunctioning.

I had not been using Calgon but bought some and did a wash with 6, had to drain it manually and nursed it through the next few washes. Then, Bingo, all went well. So now I use a coupe of the tabs with every other wash. That was about 3 or 4 years ago.

I bought the thing SH originally, it was a newly new but "dont match the new kitchen". So many people out there who desperately need an interest.  :LOL:
 

Fjell

Well-known member
Dead right.

https://www.theguardian.com/environment/2021/mar/10/tough-new-rules-aim-to-make-electrical-goods-last-longer
 

crickleymal

New member
Back in the day when TVs had HT transformers my boss used to wash the dust that accumulated out with a hose. Once they dried they were fine.
 

Stuart France

Active member
Robin Griffiths analysis is most likely correct.

It's a power diode D8 or D9 visible on the PCB silk screen print.  It will be 1N400x so may as well fit the 1N4007 which is as high a voltage as they come.  I probably have some at work, if not use the 1N4004 which is the 400 volt one.  PM me with a postal address and I will post you the parts.

It's smoked because its rated at 1 amp and more than that must have flowed due to various short circuits due to the excess water/detergent.  If it burns out again then,  as someone has said, the diode burning out is a symptom of a problem somewhere else, but changing it is worth a try.  Just be careful of unsoldering it if this is a 2-layer PCB.  You need to suck off the solder with solder braid before attempting to pull it out to avoid the risk of damaging a plated-through hole.    Otherwise solder the new part to the solder pads top and bottom of the board if the plated-through hole gets knackered.



 
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