cross-posted from: https://lemmy.dbzer0.com/post/36272192
My washing machine is dying in stages. It started with the same symptoms as this thread. Specifically, after filling the tube for a wash cycle, it would go straight into a high-speed spin (full of water!) for a second or two, then quit. The speculation is that the tachometer is failing.
Then the machine got worse. I now cannot even start any program. No matter what program I select, I press start and after a few second pause the start button LED just blinks. It’s a generic blunt signal of a fault. The blinks are evenly spaced non-stop, so there is no error code of any kind.
To test the motor, I followed the linked video and took resistance measurements. All seems okay in that regard. Test results:
tachometer
Expectation: any reading that is not infinite/disconnected is fine.
- (video): 70 Ω
- (my motor): 52 Ω
carbon brushes:
Expectation: should be in the range 1—7 Ω
- (video): 5 Ω
- (my motor): 3.2 Ω
field windings:
Expectation: all combinations should be 1-7 Ω
- (video): 3.5 Ω
- (my motor): 2.2 Ω
I do not have whatever model is in that video, but I think the motor is universal and my readings are in the range suggested by the video presenter. But is it fair to say these are crude and incomplete tests? I am expecting the tachometer to be bad based on the behavior.
Motor spin test
My next move was to try to make the motor spin. There is no service manual or wiring diagram for my Beko. So I inspected the motor and derived these pins:
1 brown (field)
2 black (field)
3 blue (field)
4 white (brush)
5 red (brush)
6 yellow (tacho)
7 yellow (tacho)
8 yellow+green (ground)Someone suggested this wiring:
L → pin 1
N → pin 5
jumper connecting pins 3 & 4I did not connect direct to the wall because I wanted to use the mechanical power button of the machine to turn on and off the motor (so I could quickly cut power if needed). So power took this path:
wall (220 VAC) → safety capacitor → mechanical button → motor (wiring redirected to motor instead of control panel)
When I switched it on, the motor spun for 1 or 2 seconds and I saw a white flash (I think) and the motor quit. I turned it off. Then tried to switch it on again. No response.
220 VAC quit coming out of the safety capacitor. Instead the voltage jumped around between 10 VAC and 20 VAC. So I thought I fried the capacitor or resisters therein. I checked the motor to see if any of the pins connected to ground (answer: no, so the motor was no harmed). Then I disconnected the safety capacitor and connected it just to mains and ground. 220 VAC was output (WTF… why does it work again?)
I think I’m back to the state it was in before I tried to power the motor. But I want to understand why the safety capacitor apparently flashed white and temporarily died with only 10—20vac output. I need to get to the bottom of this because I still need to test the motor for more than 1 second in a way that doesn’t cause more white flashes. Is it a bad idea to have the safety capacitor in the circuit?
I feel like if a motor is showing resistance properly, the “safety capacitor” is a spot I’d look, since caps can fail pretty easily, especially at 220vac. You’d just get a replacement and try that.
Right but I think that safety capacitor (SC) is the last thing I care about. IIUC, I could perhaps even simply bypass the SC because it’s merely improving the power quality/safety. It’s not worth buying an SC unless I can fix whatever is broken. If I could get the machine working, I could then of course consider replacing the SC as a final protective measure – but I’m not even sure anything is wrong with the SC.
The task at hand is testing every essential component of the washing machine, starting with the motor and tacho. I would like to understand what happened with the SC and motor though. Did I wire the motor wrong which caused the SC to flash and produce bad output for a moment? I don’t want to repeat that. I could power the motor directly without the SC, but if the motor is doing upstream damage then I guess I wouldn’t want my breaker box on the chopping block.
Possibly your motor is having an insulation breakdown when 220v is applied. Looks fine when testing with an ordinary multimeter and it’s low supply voltage.
So everything looks fine until it powers up and then you get a failure of the insulation on your motor windings, either failing to ground/frame or across windings in the motor. This flashover would likely fry whatever control components are in your main board, and it’s possible that your safety capacitor has a set of polyfuses in it that temporarily go high resistance when excess load is applied.
To check for an insulation breakdown you’d really need a megger which can apply 250/500v to the motor windings to check the leakage to ground/between windings.
