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Maytag dishwasher #MDB7749AWB1 - Dead in the water


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10 replies to this topic

#1 skintdigit

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Posted 07 November 2012 - 01:40 PM

Unit is 17 months old. Acting like FUBAR keypad...no response for normal function or diagnostics. Drain motor runs for designated two mins. when I run the diagnostic for checking the control board by disconnecting ribbon cable and re-establishing power to the unit.

Thought I'd verify by ohming out the keypad and looking for a short or open, but I do not get any resistance readings when checking any combination of pin sockets on the ribbon cable and depressing the corresponding key. Likewise, no voltage drop on any function circuit with a diode test, regardless of polarity.

It does not seem likely that all the function circuits on the keypad would be open...any observations?


SD

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#2 Samurai Appliance Repair Man

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Posted 07 November 2012 - 01:56 PM

Thought I'd verify by ohming out the keypad and looking for a short or open, but I do not get any resistance readings when checking any combination of pin sockets on the ribbon cable and depressing the corresponding key.


Bad touchpads are exceedingly common in these units. Sounds like that's what you have going on here ==> http://www.repaircli...ber=MDB7749AWB1

Touchpad-and-Control-Panel-W10356467-013



#3 skintdigit

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Posted 07 November 2012 - 02:07 PM

Yep...would still like to verify. Otherwise I'm just a parts swapper. Seems like I should get a resistance read somewhere...

SD

#4 RegUS_PatOff

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Posted 07 November 2012 - 02:38 PM

do you have your OHM meter on a high enough scale ?
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#5 skintdigit

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Posted 10 November 2012 - 10:36 PM

RegUS, yes...have tried ohms, kiloohms and megaohms.

No dice.

#6 Samurai Appliance Repair Man

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Posted 11 November 2012 - 07:33 AM

Replace the touchpad and move on to the next call.

#7 skintdigit

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Posted 11 November 2012 - 10:13 PM

Thanks, guys. That's what I'll do, Samurai. RC is out of stock...BTW.

Will pull the original apart(once the replacement is installed and the unit is functioning) and see if I can learn sumpin'.

Domo

#8 Budget Appliance Repair

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Posted 12 November 2012 - 06:40 AM

What you are most likely going to find is, right where the ribbon tail exits thru to the back side of the console the traces are going to look blackened/burnt.

One I just pulled apart and many others that I have inspected appear to get moisture migration into the ribbon membrane or just the stress of the ribbons bent back around and under the control board and the traces start deteriorating. I slighted scraped the blackened areas of the trace that should be sandwiched between two sheets of plastic and the one layer of plastic actually was deteriorated so much with just gentle rubbing the black and the trace rubbed away or the trace was already gone and broken at the area and the black carbon arch looking marks where just covering the trace void area.

You're not going to have much luck in any type of repair to any membrane touchpad because of the way it is all glued together in multiple layers of plastic and if you separate the plastic sheeting that covers the touchpad ribbon tail it will just pull all the traces off with the sticky.
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#9 Chat_in_FL

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Posted 13 November 2012 - 06:42 AM

right where the ribbon tail exits thru to the back side of the console the traces are going to look blackened/burnt.


I've wondered if adding an extra dab of sealant in this area would prevent future failures, having replaced the panel in some dishwashers multiple times... I guess it couldn't hurt to try?
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#10 skintdigit

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Posted 29 November 2012 - 01:41 AM

Thank you all for your comments. I've installed the new console and all is hunky-dory again. Decided to tear the old one apart this evening. Pulled off the outer cover with the labels on it and laid eyeballs on the traces, diodes and clicker buttons underneath. Don't see any burned spots, gaps, or water inside. Must've fried a diode or two(man, they are tiny things). There are a dozen or so test points on the membrane that can be accessed by poking with a sharp ohmmeter probe. Will fiddle with it next couple of days...if I find the failure point, I'll post up a photo or two.

 

Domo,

 

SD



#11 Budget Appliance Repair

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Posted 29 November 2012 - 07:46 AM

Look at the ribbon cable very closely right were it exits thru the console to the back side and bends over behind the control board.

 

The whole plastic overlay that has all the diodes and switches can now be carefully peeled off to were the ribbon goes thru the console and you will be able to see the area better.


Edited by Budget Appliance Repair, 29 November 2012 - 07:47 AM.

William Burk (Willie)
Willie's Budget Appliance Repair
Eureka, CA 95501




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