Samsug washing machine. Power supply DC41-00189a board issue

[Soulzink]

Hi everyone,

I am trying to fix a samsung washinmachine power supply main board.
I already replaced it with another one to fix the machine but i want to try understand the issue with the old board.
Therefore i hope to be able to get some help to explain what to check in order to troubleshoot.
The power supply board reference is the following: DC41-00189a
I have followed one thread (https://www.badcaps.net/forum/troubl...roblem?t=67604) and have done the following check:

- Big relay (GT 1A 12D) click when 12v dc is provided and shows 0.00 ohm resistance
- Main fuses are good
- Main 2 big capacitor seems good (tested whithout desoldering but got good capacitance value)
- Tested some diode too and didn't find one wrong yet

Context:
My washing machine used to run fine and some times when i started a washing cycle it would run and turn Off rondomly.
I just had to switch it On again and push the resume button and it would resume the cleaning cycle where it left it.
Given time, it started do it more frequently until a day where this was off and i couldn't turn it on.
Hence I would give a little kick next to the power supply main board. It sometimes helped but only 2,3 times.
Now I have not used the board for a long time (>1 year) and wanted to try troubleshoot it to learn more.
When i tried it again on the washing machine it worked and was able to launch a washing cycle but shortly after it turned off.
There is one special aspect with this faulty board. When it is connected to the machine and is connected to electrical socket we will here a continuous click from one of the big relay.: it will make contact (close) then open, again and again.
When it was randomly working, it used to make it too but when it was working this cycle clicks didn't occur. In fact when connected to power socket it should click once and stay closed.
Also, I found out that there is not constant DC voltage among the board: it is flickering (1v , 2v, 5v then 0v, 1v, 2v, 5v). It is synchronised with the cycling clicks.
I noticed a smps transformer but not sure how to test it.


Hence, if you have any help or suggestion, please let me know.

Thank you in advance

[klynstronic]

Hi. I would first clean the circuit board and check for any potentially sulfated traces, as well as cold solder joints and component contacts...optocouplers, etc. Best regards.

[Soulzink]

Hi klynstronic,

Thank you for your help.
I didn't notice any bad component or sulfated/overheated traces. Therefore to my eyes there is nothing looking wrong.
I already tried to reflow some solder joint but not all (i vould say maybe 20% off all solder joint).
I did it where I think there was big load of current and heat. To be more precise around big relays and capacitors and the chip behind the huge heat sink.
But there was no improvment.

Can someone explain the main principle of power supply main boards ?
I understand there is 230v ac incomming from power socket but then ?
Is it converted into dc directly within the smps transformer ?
what about the bridge rectifier ?

I want to try troubleshoot from the start to see what component is not providing its expected voltage.

Here is a list of the main component i noticed:
- 2 big relays (Gt 1a 12d - 25a 250v ac - 12v dc coil)
- 1 big bridge rectifier
- 3 smaller relays ( 12v dc coil)
- one smps transformer with 5x2 pins
- one pwm controller next to the smps transformer
- 2 voltage regulator (one 5v output and the other is 15v output)
- one big component (icmp ??) That is beneath the huge heat sink
- 2 big capacitors 820uF 250v
- other small capacitors
- bunch of fuse, diode and resistance

I consider myself a newbi but want to learn.
In addition to the test made on relays, capacitors, diode and fuse, I have replaced the pwm controller but nothing changed.
My guess is that nothing will work if no constant dc voltage is provided... so trying to check where the ac is converted to dc and how.

Hope this can provide additionnal information.

[klynstronic]

Hello. I don't think you're a beginner. Do you have a microscope to observe the circuit? In fact, you can see many things invisible to the naked eye. As you know, transformers step up or down the voltage, which is then rectified by diodes to convert AC voltage into DC voltage, which is filtered and stabilized by capacitors, resistors, etc. You can also observe the pulses with an oscilloscope. Best regards.

[CapLeaker]

What Samsung model washer is this?
Here is another thread for you to read: https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-power-supplies-and-power-supply-design/81352-samsung-washing-machine-won-t-power-on-dc41-00189a

https://www.linkzuhause.com/samsung-washer-stopped-spinning-wf80f5ebp4w-dc41-00189a/

As for the clicking relay. Is it the main AC relay that clicks in the corner? There are 3 things to check. One you already did and that is the relay. Then there is a DC enable circuit and there is a 12 or 15V regulator and with that there are some capacitors to check too.
While your at it, take that big heatsink off like in the vid on the second link and put new paste. Also desolder and resolder that IC with fresh solder.

edit:
Here is a service manual for a washer that uses the same board
https://www.manualslib.com/manual/25...06-Series.html

edit #2: look at page 54 on the pdf... It's not the same washer but the idea is basically the same.

[CapLeaker]

Finally found the right schematic for this DC41-00189A

Not easy to find!

[Soulzink]

Hi everyone,

Sorry for late reply, I spent my entire sunday fixing my car.

@klynstronic : Well, I enjoy trying to troubleshoot and fix some eletronics in order to understand/learn and sometimes buy very low faulty product to repair them for myself. So I got some tools including a small numerical microscope but I didn't follow engineer school and therefore I only know of thing I can read and see on the internet
As for the faulty board, after spending lot of time trying to check traces and other things, I reflowed as suggested all solder joint which took me a long time. But it didn't make any change. Still that clicking relay and voltage flickering from 0v to 5v.
I tried to check smps transformer pins but didn't get any voltage reading. However it seems the coils within are still good (tested in continuity mode). So either he is not getting AC or something is preventing it to proceed like a ic controller "shuting it down".

@CapLeaker : Hello, thanks for the help.
My washing machine is a samsung WF1114XBD.
Thanks for the two links. In fact I already saw them before. The first one is from someone having kind of the same trouble with no constant voltage. But I didn't have a short or at least nothing seems shorted. Also the second link was talking about bad traces but I didn't find any bad in continuity mode. Maybe I will have a double check on all traces again just to be sure but it won't be easy to be 100% sure since it is random. For instance on saturday night while trying to check voltage, the board stopped clicking and board was working again. It might still be working today (I will check when i get back home) but as always I would launch a washing cycle and it would stop in the middle.
It looks like either a bad contact, or a "restart signal" cycling for some reason, or a "tired" component (capacitor, resistor, diode). Since I have tested all relays contact and reflowed all solder joint, I think contacts are good but can't be 100% sure.

Regarding the clicking relay, you are right. It is the one at the bottom left (top view). I found out that some flickering dc voltage is provided to him hence the encountered behaviour when the card is not working and the clicking stopping when it works.
I find 20v next to the smps transformer when this works and it is provided to first voltage regualtor which output around 17V and is provided to second voltage regulator which output around 7V. But when card is faulty and relay clicking, I find no voltage around smps transformer and flickering dc voltage around those regulators. What do you call DC enable circuit ? PWM IC ?
As for the capacitors, I didn't desoldered them since everything is glued and it is very difficult to remove them but when I gave it a try on saturday, I found out that multimeter is showing good capacitance for each of them (2 big, and the other smaller ones). But since they are still soldered I can't rely on that 100 %.
I will probably change thermal paste and clean the board but only if I manage to troubleshoot it because I guess it will be a pain in the a** to remove that glued heat sink xD

Regarding the manuals, Thanks a lot, I didn't manage to find any on my own. I will have a deep look at it tonight and see if I can go further


Thanks again for all your replies.

[CapLeaker]

Soulzink
I had written my post #5 before I found the correct schematic in my post #6.
Reading your last observation of the washer, I suggest heating up the board with wifeys hair dryer, so everything is nice and warm (but not that hot you burn yourself) and then start a washing cycle.
My post #6 has the schematic for your power supply and you'll see how that relay #1 works.
Edit: Here is a layout of the PSU on where what is.

[Soulzink]

Hi everyone,

Thanks a lot mate for all shematcis 🤗
They are very usefull and reading them I can see that I was almost right on my understanding of this circuit xD
Yesterday I tried again to turn On the washing machine and it was still working.
I launched a washing cycle and it turned Off ( 20 min from start) and On (after 30 min maybe) then it stayed On for an hour.
Surprised I came by checking the maschine and just then motor stopped abruptly and saw a flashing light somewhere around the maschine (not sure where). Everything stopped and breaker popped.
I removed the board and checked it: main fuse from AC side was blown.
So I think either the tired component finally gave up causing a short or a security mecanism has gave up 🤣
I will continue digging this a bit with shematics around the AC part of the board. My guess is that the bridge rectifier has blown.
I will try desolder it and check it in diode mode.

[CapLeaker]

interested to see what you find!

[Soulzink]

Hi there,

So I checked the board again before doing anything.
I found that there was around 0.5v in diode mode across all pins and any direction from the bridge rectifier.
Very weird so I decided to desolder it. I tested it again and it was fine xD.
So I kept desoldering things linked to its trace to test them individualy.I ended up desoldering the two big caps and one resistor. However out of the board they were showing good values.
Back to the board I noticed that (+) trace and (-) trace from bridge rectifier were showing continuity. Following them I decided to remove huge heat sink and have check.
Here it was ! There were two black spot on 4 pins of the big IC. Following the provided schematics (thanks again it is a IKCM15F60GA.
I had a lot of difficulties to desolder and remove it. I damaged two trace and there is a small hole into the board now.
I think I can manage to fix those later.
At this point I am not sure if this faulty component was the cause of all this or if it is only a consequence of another failling thing.
I tried to check the component linked to those 4 burnt pins but everything seemed fine (caps, resistor, diode).
So...... I ordered another IKCM15F60GA, a new bridge (just in case) and a fuse and will try again when possible xD.
I will revert asap

By the way, I helped one familly member today to clean its Miele from 2005.
I was extremely surprised when I found a pack of shematics of all circuit provided and stored inside it.
I was thinking they should be always provided and it seems they did this in the past...

[CapLeaker]

I figured it now would be that IC under the heat sink. It's a known issue with this board. Keep on going!