Appliance Repair

hey! i don’t particularly want to post on Reddit, and i just found this community. hopefully there’s someone here who can help.

don’t let me jump to a conclusion here (the good ole X/Y problem we call it in software).

i recently moved into a new house, and my dishwasher’s performance has been next to useless. the first weekend i moved in it had a leak detected so i took the opportunity to take the whole mfer all the way apart and clean the filter and check all the guts. (i ended up removing the sensor completely cuz the false positives were driving me nuts; also this experience made me start distrusting the machine itself)

after this, the residue from the detergent went away, but it wasn’t cleaning anything that wasn’t just something i could rinse off in the sink. i ran dishes through 3, 4, 5, 6 times. in the meantime i started pre-heating my water before starting the machine, based on advice from this Technology Connections video. finally today i hand washed most of the dishes so i could use the dishwasher cleaner i bought.

the dishwasher cleaner was this product: “Finish Dual Action Dishwasher Cleaner: Fight Grease and Limescale, 1 Count”. the idea being if there is some excess lime built up the pressure may not be adequate. the way it’s meant to work (i assume) is you remove a sticker to expose a wax plug that is melted by the heat of the water during the cycle. i set the dishwasher to the most intense setting: heavy wash, extra hot, sanitize. took the thing 3 hours to complete the cycle. i come back, and the wax plug is 100% intact. thus the conclusion: the water isn’t getting hot enough during the cycle even with preheating. based on this i’m assuming that my water line is simply too long for such a modern machine, which (assuming based on the video) is trying to minimize water waste and not sampling enough hot water to get up to normal operating temperature.

the reviews of the machine seem positive, and negative reviews don’t indicate this as a normal issue regarding the effectiveness of the machine.

hope someone can help, because it’s currently an overpriced drying rack for my hand washed dishes.

it’s the Samsung DW80K5050

here’s the manual for the model: https://downloadcenter.samsung.com/content/UM/201610/20161012093615322/DW7000KM-02025B-01_EN_CFR.pdf

The DVD player wouldn't start, I opened it and here it is. How do you call this composant (1009) ? Do you think it fried because the fuse fried first? How do you even change this type of thing?

It stops the second I unplug the fridge, and starts the moment I plug it back in.

Maybe my Google fu is weak, but I can't find many answers. It never used to do this. And at least for now, the temperature is fine 🤷‍♂️

A washing machine is trapped in a fault state even though all the components function (AFAICT). The controller board has two ports:

• ISP (to attach an ISP programmer to flash new software)
• USART (4-pin serial port: 0v, TX, RX, 5v)

I’m guessing the ISP port is useless without whatever proprietary software is needed. But what can the USART do for me? Can that be used to obtain the error code and clear it, or reset the board to the factory state? Has anyone done that, without documentation?

My washing machine had the same symptoms as this one, which is the same make but different model. It suggests a bad tacho. I need more certainty before buying parts.

The state worsened. Now I just get a non-stop continuous blinking LED with all flashes evenly spaced (thus no error code).

Someone told me the advice on this page is sketchy. IIUC, that page says to hand-spin the motor while the tacho is connected to an ohms meter. I get very little variation. If I give it a spin as fast as I can, it goes from 52 Ω to 52.8 Ω.. or 53 Ω on one occasion. Someone said it’s wrong or bad to put current through an ohms meter. So is that a bad test?

There are different kinds of tachos. Mine uses a coil, which I suppose implies that I an dealing with the rotating magnet variety.

voltage test (I am ill equipped)

Some people apparently read the AC voltage of a tacho while spinning it. My meter only has 2 scales for AC voltage: 500 and 200, which are far too high to detect anything. Should I buy a meter that detects AC mV?

Hz test (I am ill equipped)

My meter does not have frequency. Should I buy a meter with Hz?

scope test ~~(I am ill equipped)~~

Apparently an oscilloscope app can be fed by a smartphone’s mic input. But I do not have an AOS 6+ phone.

(edit) There are a couple FOSS desktop apps:

• PulseView
• xoscope (I will not link it because the project is Cloudflare-jailed)

So I might try this. I think the input can simply be wired to the mic input, but it’s better to build a circuit:

• https://www.instructables.com/Use-Your-Laptop-as-Oscilloscope/
• https://web.archive.org/web/20250116090641/https://xoscope.sourceforge.net/hardware/hardware.html

earphone test (strange result)

I connected the tip of the 3.5mm phono connector for audio headphones to one tacho lead and the middle segment to the other lead. When I spun the drum by hand, it sounded in the right speaker just like the drum sounds to my naked ears as it spins. That can’t be right. Must be all in my head. Is this test useless?

compass test (unlikely to be useful)

I could theoretically run a compass app and hold the smartphone up next to the tacho as it spins to see if the magnet is still magnetic. But I’m told it’s unlikely that the magnet became demagnetized unless I sent 230 VAC to it -- (and I did not).

hotwire tests on other components

• 230 VAC → universal motor (spins fine)
• 230 VAC → drain pump (spins fine)
• 230 VAC → water inlet valves (opens fine; water flows)

what now?

I don’t understand why a tacho would go bad. So how should I test my tacho? Should I buy a meter that does frequency and low AC voltages?

Ultimately I need to know what the PCB thinks is broken whenever it is told to run a program. Is the PCB doing an ohms test to test the health of the tacho?