[tonyt411]

Hello all. I recently received an "lr" error on my MAH5500 neptune washer. Upon thorough examination, I isolated the problem to the motor control board. Removed. Here is what I have found; Surge on Orange/Yellow circuit. Burnt IC3, R35 open and toasted, R38 & 39 possibly shorted, R40& 41 show signs of thermal breakdown and are the only ones that do not test positive for continuity. Q5 & Q6 read very low values on the diode test relative to the other 4 triacs. I have obtained the nex wax motor, inspected the main lcd control board for the r11 issue and found no damage. |Can anyone give me some insight into what caused this as well as a listing of the individual component values and/or part details. I am well aware of the motor conversion kit issue and am doing this repair instead for financial reasons. If I can repair this board myself for about 10 bucks instead of 200 +, it is well worth the effort. Thanks to all in advance .
tonyt411

[denman]

Here is a site with some service info
Maytag Service Library

Sounds like a major melt down
I would take a run to the local dump, they probably have a ton of these anchors perhaps you can steal some parts or better yet take home 2 or three units for the parts you will need in the future.

I know this is not much help but junk is junk.
Possible causes could a shorted motor winding or the output control device.
Also since you had such a large surge there is a good chance other IC's and transistors were taken out.

You have probably already done this but if not, I would check if you can still get in on the recall.

[tonyt411]

|Thank you so much for the prompt reply. |I expected to float alone out here for awhile before some bored soul got around to posting what he probably had stored in his memory.
|As for the lawsuit, that's a lost cause. Claims deadline was in mid 2005. I called Maytag anyhow in the hopes that I might get a hold of a sympathetic technician ( perhaps even a plain old operator w/ access to low level schematics would have done nicely ) that could just give me these little pearls that have become like the holy grail to me. Whatever. Courteous, but no better off than before.
Circuit board repair has been compared to surgery before and it might even require more dilligent preparation. Thank you again for the link to the service manual. Unfortunately, the only reference to the motor control board is method of panel testing and their solution in the event it fails the test; remove and replace board. I can hardly affors the 3 cent resistors these days. Let alone a 200 dollar legacy fru board that could JUST AS EASLIY fry as well if I did not take the time to properly diagnose the environment.
Here in Alabama, gas just went up to 3.82/gal. My wife is washing hers' & our daughters' underwear in the sink as well as spending 20-50/ trip to the laundromat a few times a week. I'm sure most of you guys are suffering too, so don't cry for me. Just know that it would reallly make my day if these values were to be posted here pretty soon.

Holdin' out for a miracle,
Tonyt411

[techknight]

I can give you the values, but it isnt really going to help you any at all.

IC8 is most likely fried. that chip is the main microcontroller, and is a custom MASK ROM programmed CPU from emerson.

now its possible its survived, but its highly unlikely.


it looks like im going to have to make it my destiny to write software for an AVR or a PIC CPU. or even a 6805. I know how to write 3-phase motor controller software, as ive wrote ASM to run those small brushless 3phase RC copter motors.

the problem is. im not exactly sure what all the pinouts are on the connectors of the controller board.

I know there is a small plug JP4, which goes to 2 opto-isolaters and 2 lines go to the MCU. im not sure what the signalling on that plug does. I know theres probably an "on command" or some crap for that motor.

but that also leaves JP3. i dont know what this is for either.

does the main motor also reverse? im not sure how the front-load washers work to be able to design microcode.

Any ideas?

[techknight]

also a good start:

http://www.atmel.com/dyn/resources/p...ts/doc2592.pdf

[techknight]

also this should work:

hxxp://www.atmel.com/dyn/resources/prod_documents/doc2592.pdf (change XX to TT)

that data they give you should work just fine. obviously for test examples, they are using a hall effect device which is part of the motor, and they are using a pot for speed control. youll have to change the program around to allow direction changing (dont know if needed or not). 2 or 3 fixed speed settings in s/w, etc etc etc.

[techknight]

i repaired my motor controller last night and its alive again :-)

trick to these is look at all of the phase output drivers. the components are the same between each phase. You have to reverse engineer the circuit on the good phase to figure out what the unreadable parts are on the blown phase.

I also recomment using IRF740s as replacements of the 644s. they handle the surges and back-EFI voltages better.

now the puppy is alive. :-)