How to repair a Motor Control Unit for a Whirlpool Washing Machine

[michaelabbasi]

[ Specified attachment is not available ]Hi, I am looking to repair the MCU of a Whirlpool duet washer and really lost as to the parts are, they dont have any numbers to identify and order a replacement. The Bridge rectifier and the Power transistors(transistors are combined in one package) have no id's. Would appreciate any help in this regard. Thanks.

[eKretz]

Have you determined whether there is a problem with either of those? If they are functional you don't really need to know what they are...

[michaelabbasi]

Circuit board has two fusible links blown as well as a blown green colored SMD resistor which is part of two other resistors. Here is a picture of the same.

[Digorion]

Model numbers may be printed on the other side of rectifier / ic.

You can also try to find schematics acording to the mcu's model number.

[michaelabbasi]

I have tried to find the Schematics of this MCU on the Internet but no luck so far. Also I have read some where that the manufacture of this MCU deliberately hide the part numbers so that they could sell them at an exorbitant price. The Model number of this MCU is WPW10374126, If some one can help find me the schematics that would be great.

[pbarton]

That big chip could be from the SANYO  STK621 family.

[Digorion]

What model of washing machine?

[michaelabbasi]

Its a Whirlpool Duet Model Number: WFW97HEXL2

[michaelabbasi]

I unsoldered the chip and found out the number to be on the back side, which is IRDAKO726350B lets find out where can i get it from. Thanks for all the help. I will keep you posted with the repair job.

[DarkZero]

big chip is a Variable Frequency Drive for the motor and its 100% dead since the current sense resistors are blown. resistors are 0.05ohms i would unsolder the chip and dead resistors fix the the fusable bridges, power it up and check the voltages around small mcu if they are present order VFD chip replace resistors and u are good to go.

if there are no voltages,  power it off w8 for capacitors to discharge and check for shorts on small caps if u find shorts the small mcu is dead and that's where the repair ends im afraid.

[michaelabbasi]

Thanks for the advise. Problem is to find this IGBT, none of them is available in US, I had to order one from China, will take a month to get it.

[Gyro]

Things were sooo much simpler with brushed motors and discrete triac controllers. 

[sandmon]

Hi,

I have the same board but I blew one of the chips and a resistor.  I can't read the resistor part number and was hoping if anyone has any images showing this resistor value that is usually on top of the resistor.

I tried to Ohm the resistor but since its blown I don't know what the value should be. 

Thanks.

[amyk]

You could trace the circuit out and compare with reference doc: https://www.power.com/sites/default/files/product-docs/lnk302_304-306.pdf

Although in this case it looks like a chain of high-value resistors used as a divider to generate a phase reference to the MCU input, so maybe it's not part of the power supply, but the fact that the PSU IC is blown does not bode well for the state of the other components on that board --- it's an unisolated buck regulator.

[DavidAlfa]

Looks like 1R00

[IanB]

A general thought about this thread is that fusible links probably don't just blow for no reason. So as well as repairing the electronics, it would be as well to test the motor for shorts or mechanical problems before applying power.

[DavidAlfa]

The LNK ic went k-boom in all these boards, likely after a high voltage trasient or moisture ingress.
The main issues is thats not an isolated converter, but a buck converter, so if the output transistor shorted, 300V went everywhere before blowing up.
Very clever design to make you buy a new board when it fails.

This board is similar. 1R00 resistor too:

[DavidAlfa]

I don't think this board has cheap neither easy repair, it looks like a major failure.
Watching these green fuse resistors, the big power module has clearly failed too.
The full bridge rectifier is used in a weird way I don't understand completely.
C1425 (C5) is charged during the negative half-wave.
C1424 charges in the positive one. But when neutral goes positive, it seems the voltage will double?

[sandmon]

I ordered a new board instead of trying to fix the components. 1R00 was the correct resistor in case anyone needed it on the future.  I attached the age of the new board. 

[ange1azrae1]

I'm having the same issue & need to replace a chip I can't identify from the MCU see images. These are with the heat sink off and the second is the chip I need to ID removed

[MarkF]

That looks like a diode bridge.
Something like this (probably not identical part):
   https://www.mouser.com/ProductDetail/Diodes-Incorporated/GBU806?qs=mQbszxtPdlOoMOdNR14vZA%3D%3D

[DRJIMD]

https://www.avnet.com/shop/us/products/onsemi/irdako726350b-3074457345639569336/

IRDAKO726350B

everyone wants to sell multiple of over 20.   So I guess it is ebay for the part.

[schnittker]

Motor control board W10374126
Mine is in a Maytag, but also used in Whirlpool
After the second replacement, this time I decided to record values of components on the new board before installation and repair my old one as back up.

The main chip that often blows is Power Integrations LNK304GN. I replaced with LNK304GN-TL. Digikey 596-1022-1-ND

The three sense resistors that often blow are 0.05Ohms size 5025. I replaced with Isabellenhuette VMP-R050-1.0-U  Digikey 4423-VMP-R050-1.0-UCT-ND

The little resistor next to the switch is a size 3216 labeled 1R00 which is 1Ohm. I used Vishay CRCW12061R00FKEAHP Digikey 541-1.00UCT-ND

My ceramic capacitor next to the switch was also damaged. On my new one I used and LCR meter to measure it to be 0.1uF. Its a size 2012. I replaced with Kyocera KGM21AR72A104KU, Digikey 478-KGM21AR72A104KUCT-ND

For my burned traces I replaced with some thin copper wire
Note that I bought a repair kit off ebay which was supposed to have all the right components, but the sense resistors were wrong, and it was missing the small 1Ohm resistor next to the switch.

[poldim]

I just had my machine stop working yesterday.  Pulled this board out and see similar damage:

• the LNK304GN is split open
• one of the sense resistors got hot enough to airgap the conformal coating
• the top right fuse trace is split (the top left took on some heat but still has continuity).

Odd thing was when I was trying to confirm if the right most sense resistor is fried, they ohm out at 12 ohms.  I checked the other two and same exact reading.  However, going between any two pins on the chip right above the reistors (I think thats the vfd chip?), it correctly show .1 ohms.

I'm going to order all of these parts from digikey and hope to do the repair this week.


Larger size:
https://photos.app.goo.gl/9fVwgetm8zUA8wC77

[elecrtoguy]

Greeting all. First off I am no expert, just a novice guy. Anyways, can some of you give me links as to where to find the different resistors, etc. I did manage to get the chip from amazon in a multipack of them, and I do have some resistor collection too. But appears from what I read there some called sense resistors.. I believe those are the ones that are in a group of three.. thanks