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Our 15-year-old washing machine stopped working. I can still choose a program and it starts just fine but it then stops after ~5 seconds into the program. That can't be too hard to fix. Things don't just break.
So I took it apart to have a look at the electronics.
So I took it apart to have a look at the electronics.
And look what I found here. There's an Atmel ATMEGA32L on board with a handy ISP board on the back side. Wow this photo looks like an ad.
I was hoping to find a busted capacitor that should be easy to fix, but instead, I discovered something else.
This mysterious little buddy looks burned and so does it smell.
This mysterious little buddy looks burned and so does it smell.
It's an ST VIPER12A-E Low power offline switched-mode power supply primary switcher https://www.st.com/resource/en/datasheet/viper12a-e.pdf
The backside of the PCB doesn't look any better. It also looks burned and from the big traces and clearance between the tracks, we can guess that this is indeed the high-voltage side of the power supply.
I decided to just unsolder the Viper and the adjacent diode and replace them with the same model. My local Conrad store didn't have the Viper so I had to order it online at https://www.ebay.de/itm/111108050630. I needed it quickly so 2,99 € shipped was tolerable. Diode from Conrad.
Just a quick check after unsoldering and soldering reveals that the joints are alright. Time to place the PCB back into the washing machine.
All of the connectors are unique so it is impossible to connect the wrong ones. I reconnected all of those and gave the machine a test-run. It started fine. Let's see if it can complete its cycle.
Well. It kind of worked. The program runs fine now but I could see very regular blue arcs reflecting on the floor. I disconnected the machine immediately.
The machine has brushed motors. After 15 years they probably are well worn out.
The machine has brushed motors. After 15 years they probably are well worn out.
This is the motor with the belt undone already. The big boy does not fit through the narrow back of the machine so I had to lift the machine up and grab it through the bottom.
Model number for datasheet nerds
Sheet data for number models
This being a brushed motor, there two brushes (not visible here) that are in alternating contact with the commutator (marked in red). The brushes wear off over the years. This does not happen with brushless DC motors as found in computer fans.
Here you can see the left brush housing and the spring-loaded brush that is in contact with the commutator.
... and without the housing
New brushes are almost as long is this brush battery with only a spring behind it. This old brush is fully extended and reaches out just 4mm / 0,15in out.
I went to a speciality shop that sells these exact brushes. The expert in the shop then saw that there are NEW and OLD versions of this exact brush. I need the OLD one that they don't have... They changed the connector position from bottom to top.
There are so many types of these brushes and no standards. This one is almost correct but has the fittings and thus would not fit on the motor.
I found the (hopefully) correct one online and am awaiting delivery in 3 business days. No washing over the weekend.
I found the (hopefully) correct one online and am awaiting delivery in 3 business days. No washing over the weekend.
Look what came in the Mail today.
They should be good for another solid 15 years of service (which the machine will never see).
The holder fits perfectly and the screw holes, too. Finally the correct part. Let's screw it in and...
... ensure they have good contact with the commutator.
I love problems. Getting the motor back on is almost impossible. It always springs out of the fitting or falls down. The books on the floor don't help, either.
Found a solution. Throw that machine over and press and hammer the motor in. Worked like a charm. The screws widen the fittings so the motor won't fall off.
Even though the screws provide no direct physical connection to the motor, it holds the motor incredibly well. Did not move a millimeter over 15 years. The screw spreads the fitting like a dowel in brick wall.
After putting the machine back upright, I only had to reattach the belt that drives the drum. Because there is a lot of tension it is much easier to rotate the wheel that is driven by the belt.
I couldn't find the self-test and debugging key combination for this machine, so I just started a spin-dry program. No sparks!
Put it back into its place and made a smol success b-roll for you guys. ;D I hope this will be helpful sooner or later. Cheers!
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