Wash machine dead help.

[ivtec]

Hi good folks;hope you all had a great new year entrance;afamily member asked me to look at their wash machine Maytag MVWC465HW that is dead no leds turn on , i already took out main board but it's hard to troubleshoot due to the amount of wax covering all the board both sides,all fuses to the rectifier and filtering are good, tried to order it but no boards available and cost more than a new wash machine,so i'm trying to repair it at component level,i would appreciate if you could lid me the way any tip that will help me to fix the main board,there is no parts available for this mod# so it seems,power supply is bad somewhere, could be any component in the power supply, suspect U4 AC-DC Off-Line Switcher, Integrated MOSFET, but there are no Part # or marks on top of the Chip and is covered with WaX as the whole board which is hard to test components ,i have to scrape the wax around components to be able to test, so far don't see anything that maybe suspect besides U4 Mosfet but since no part # visible, it's similar to this one see link bellow ; ,don't know if it would fix the issue ,
So i'm stuck here with no info on the board,they sell other boards since it seems these boards are made by Whirlpool, but none for this machine with part# W10857311 ,and they costs as much as a new machine,wouldn't be wise to order an expensive board that not sure work with this machine,it's not worth it for a machine with 2 years and no assistance at all, if i can find the crupit component fine if not not worth it,thanks for trying to help, if you think of anything that i can check on this board please do,thanks in advance



https://www.newark.com/power-integra...RoCMdsQAvD_BwE

[R_J]

Re: Wash machine dead help.

Have you checked if there is any A/C getting to the board? Since the fuse is good, I would not be to quick in suspecting the board.

[redwire]

Re: Wash machine dead help.

It's very hard to work on boards with a conformal coating, you need sharp needle probes for the multimeter.

But I see damage and corrosion? in the corner by J3/J12 what happened there. One part and pcb trace look sad.

I would check the fuse (reddish orange square box by J5). It looks like 12VDC SMPS and a 5V regulator for the MCU. 5V should be at J8 pins VDD_UC, VSS_UC.
Whirlpool repair W10857311

[stj]

Re: Wash machine dead help.

try recapping it, or at the very least - c72

if it is wax, just use a hot air gun to make it run off the board

the interesting question is: why does it have an I,R. led + reciever? i'v never seen a washer with remote comms!!
(i'v also not seen one before with an ARMcore cpu!!)

[ivtec]

Re: Wash machine dead help.

Thanks guys; Redwire i the corner by J3 ,i did scrape wax to test Diode B1 and Switch R22
Fuse Reddish/orange square box J5 is good, Can i test Volts connecting board to power without load just with power cord? also the led on the middle of the board should be lit if the board had power and it's not,that's why i say power is bad somewhere?and what you guys think about my suspicion of U4 see pic;

[budm]

Re: Wash machine dead help.

So what Voltage do you have on the main filter caps c70, 71?

[ivtec]

Re: Wash machine dead help.

Thanks Budm i found a Technical information scheme and detail troubleshooting info of this machine,i'm going to check some voltage points per instructions these next days,

[budm]

Re: Wash machine dead help.

So check and see if you have AC Voltage to the board to feed the rectifiers or not and if DC Voltage on the main filter cap for the SMPS IC to run is present or not.

[kaboom]

Re: Wash machine dead help.

You need to replace all the lytics in the power supply.

The one for the 5v supply (470-1000u @ 6.3/10v) is especially critical.

There's a 22(?) ohm fusible resistor in that PCB cutout near the line rectifier. Right next to it is a small filter choke.

When the MCU (or opamps feeding I/V signals back to MCU) gets bad power, the motor/triac drive fails in such a way as to apply power to FWD&REV of the motor at the same time- cord gets hot & motor smokes in under a minute. This is often misdiagnosed as "bad motor," usually with quote for new motor- only to have the replacement also smoke, or at least hum at the beginning of cycle during "balancing" or "weight sensing".

FWIW, this machine is the "new" Whirlpool VMW, the post-2018 (yours is April 2018) that uses less water on "auto"...

Panasonic FR caps are fine. That PCB has either a polyester or polyurethane coating. Use either a soldering gun or 800 degree min chisel tip and "float" a large solder ball over the coating to remove it. Be careful of the lands. Heavily tin the cap leads before attempting to remove- traces easily damaged.

[kaboom]

Re: Wash machine dead help.

Thanks guys; Redwire i the corner by J3 ,i did scrape wax to test Diode B1 and Switch R22
Fuse Reddish/orange square box J5 is good, Can i test Volts connecting board to power without load just with power cord? also the led on the middle of the board should be lit if the board had power and it's not,that's why i say power is bad somewhere?and what you guys think about my suspicion of U4 see pic;

That LED is not a power indicator. When tracing one of these, it seems to be either in series with, or driven by the IrDA LED. Yes, these have a serial port that WP uses for programming.

If the CPU is frozen or not coming out of reset, say because of bad power, that LED does [b]not[/i] light up.

It's possible to apply line voltage via the two-pin black socket, but I think the MCU program checks the status of the cycle option and lid switches before it "unlocks" and lights any of the 6 status LEDs. IOW, if you apply line voltage with the PCB on the bench, you could be chasing false-faults.

There's usually enough wire length to observe the status LED with the PCB connected and under power in the console. But again, the LED isn't guaranteed to light in an otherwise-OK-except-bad-caps situation...

I'd focus on the power supply; these controls seems solid except the power supplies. WP obviously wants people continuously buying new machines- the rigged control price clearly reflects this.

Check the fusible resistor, and the red block fuse next to the black power inlet.

Edit:
OP, I sent you a PM.

[ivtec]

Re: Wash machine dead help.

Thanks guys today i went to check voltages per service manual instruction and conclusion is the control board is bad and needs to be replaced,i also checked some voltages in the rectifier side on those 2 diodes and no volts there also relay has no volts and also no volts on the yellow choke or anywhere except in the 120v input,all the components that can be checked with my Fluke 87 and my cap analyzer check good also the board has a lot of wax and is led free solder ,i don't have proper solder iron that can deal with led free , i can work with it but it makes it hard,if i knew for sure what part i would give it a shot,and most ics are covered with wax and no Part #'s visivable ,it's like a shoot in the dark, those 3 electrolytic caps check good and the 2 diodes rectifiers also check good, Fuse 2 good,resistor 22 ohms is good,thanks guys

[R_J]

Re: Wash machine dead help.

Are you getting voltage (160vdc) across C70 or C71? That looks like the main filters for the smps
You can work on the board out of the machine, just apply a/c to the black plug near the fuse. You should have 160Vdc across C70, then using C70 ground, check for dc on pin 6/7 (they may be connected together)

[kaboom]

Re: Wash machine dead help.

Thanks guys today i went to check voltages per service manual instruction and conclusion is the control board is bad and needs to be replaced,i also checked some voltages in the rectifier side on those 2 diodes and no volts there also relay has no volts and also no volts on the yellow choke or anywhere except in the 120v input,all the components that can be checked with my Fluke 87 and my cap analyzer check good also the board has a lot of wax and is led free solder ,i don't have proper solder iron that can deal with led free , i can work with it but it makes it hard,if i knew for sure what part i would give it a shot,and most ics are covered with wax and no Part #'s visivable ,it's like a shoot in the dark, those 3 electrolytic caps check good and the 2 diodes rectifiers also check good, Fuse 2 good,resistor 22 ohms is good,thanks guys

Make sure you use the correct common reference. The outputs are stacked as such: +12 to common (across small 47-100u/16v cap, C7?), and common to -5 (larger output cap, C75, 470-1000u/10v).

Your "common" goes back to the negative side of the two 22u/250v (C70,71) caps. Secondary common is tied to AC-neutral for easy direct drive of the triacs that control the motors, valves,& lock solenoid.

[kaboom]

Re: Wash machine dead help.

Again, before condemning that board, replace the caps. They're Ltecs after all...

I've also seen several appliance repair anecdotes where replacing them fixed the "dead washer"- this is hardly a lone fantasy. Wouldn't you rather recap it instead of pay a ripoff price only to get a new board with the same craps?


Hint: unplug & warm the PCB with a hairdryer, then try it again. Your fluke cannot adequately test caps as to their suitability in an SMPS. And they're known badcaps, replace them first before overthinking this.

Would I be correct in assuming the trouble with this started as indoor temperatures dropped?

[ivtec]

Re: Wash machine dead help.

Again, before condemning that board, replace the caps. They're Ltecs after all...

I've also seen several appliance repair anecdotes where replacing them fixed the "dead washer"- this is hardly a lone fantasy. Wouldn't you rather recap it instead of pay a ripoff price only to get a new board with the same craps?


Hint: unplug & warm the PCB with a hairdryer, then try it again. Your fluke cannot adequately test caps as to their suitability in an SMPS. And they're known badcaps, replace them first before overthinking this.

Would I be correct in assuming the trouble with this started as indoor temperatures dropped?

Thanks Kaboom; i appreciate your input and advise ,all the caps you mentioned were not tested with my Fluke 87 but with my capanalyzer see link and they all test perfect, should i doubt this tester? i really hate to remove these and find out that it's not it, i could realy give it a try;
https://www.youtube.com/watch?v=Rkzj9Z4GQ7c

[R_J]

Re: Wash machine dead help.

Is that switching power supply section working at all?

[ivtec]

Re: Wash machine dead help.

Is that switching power supply section working at all?

Only voltage on the input 120v ac, no DC volts across the 2 marked rectifiers no v on U4, no volts across CR8 or anywhere in the board , with it connected to the load ,can i test board on the other side without being connected to the machine assembly without load?

[R_J]

Re: Wash machine dead help.

.

[kaboom]

Re: Wash machine dead help.

Thanks Kaboom; i appreciate your input and advise ,all the caps you mentioned were not tested with my Fluke 87 but with my capanalyzer see link and they all test perfect, should i doubt this tester? i really hate to remove these and find out that it's not it, i could realy give it a try;
https://www.youtube.com/watch?v=Rkzj9Z4GQ7c

Did the trouble with this machine start with dropping temperatures?
Did you lose power, with the machine previously working, then becoming "dead" after power was restored?

Again, those are known badcaps- now it's not always the caps, but where there's smoke, there's fire, and it's a somewhat common pattern.

In case I missed it, how old is this machine?

[petehall347]

Re: Wash machine dead help.

TR9 dont look good