Samsung WDJ1555C Repair

we use cloth diapers so the washing machine is really essential.  A while ago it started hesitating at low speed under heavy/wet load.  I thought the belt was loose, so I tightened it, but the problem persisted.  I noticed that the motor was not spinning, but instead just jerking and hesitating.  It is hard to tell this though, as all parts are black - so I put a small piece of yellow tape on the small pulley and watched it not go.

 I ordered a new motor (AU$132) from Electronics Market.  The parts manual is here.  It was the right part (DC31-00045A), but ended up not being the problem.  Hugely expensive surprise!  The new motor stuttered just like the last one, which means it wasn't the problem.

 Additionally, the new motor I bought didn't have the prong for the ground wire to attach to.  I think they either have poor QA or got rid of it to save a penny.  I wedged the ground straps elegant little slide-snap between a gap in the metal housing.

 A side note, the shoes on this washer tend to degrade and come off.  I've replaced them with the hardest rubber pad material I could find, trimmed to fit and glued on.  Tried soft rubber the first attempt, but that makes the vibrations during the spin cycle waaaay worse.

 Here is an underside view of the motor, looking from the front, under the washer.  Note that this is not how you access the motor.  I had it up to glue a shoe on.  The motor can be swapped entirely from the back of the machine, which is way easier.

A view of the main PCB (power control board?) which I believe is the actual point of failure.  Electric motors require the most electric current when they stall (see here) so I suspect that this is a current delivery issue.  Since it wasn't the motor, I bet it is this.  One of the capacitors looks kinda puffed out.  This part (MFS-AUJ2RC-00) is AU $200.  Note that the parts list linked to above mislabels this PCB as MFS-AUJ2RC-S0, which is actually the front control unit with the spinning control knob.  I checked the label on the actual part and this main board  is definitely MFS-AUJ2RC-00.  I'll order it next week I guess.

Brief motor swap steps:

1. Get behind the washer with at least 1 m of space from the wall.
2. Unplug the washer.
3. Unscrew the 4 phillips head screws holding the rear panel on.  This rear panel is just grey sheet metal with a wiring diagram on it.
4. Set the panel aside.
5. With a 13mm socket and extension, loosen the bolt which is obviously holding the motor in place, just to the right of the small pulley.  Completely remove this bolt.  There is a plate-nut that it goes through which should stay in place once you remove the bolt. (You can kinda see this nut plate in the photo below, near dead centre of the pic far below).  Only one bolt holds this motor on.
6. To loosen the belt, squeeze the two sides of the belt together.
7. Slide the belt off of the very large pulley just using your fingers.  It doesn't loosen to the point where it comes off on it's own - a little force is required.
8. Push the motor down gently until it swings away from the previously bolted area.
9. Slide the motor towards you (out towards the back) about 2.5 cm and it will fall off of the two plastic studs which hinge it to the drum.  It is heavy ~7 kg so be ready for this.
10. Finagle the motor out of the back of the washer and disconnect the wire harnesses and ground strap.  Note that you shouldn't pull on the wires, only put force on the plastic plug ends.  A small screwdriver is needed to gently push the larger plug prongs out from the back, then wiggle time.
11. To reinstall, the only tricky bits are:
1. There are two plastic "caps" which adapt the holes on the motor to the smaller plastic studs which they slide onto.  These caps should be either on the studs, or in the mount holes when you go to put it in.
2. Getting the belt back on the pulley is tight.  You will need to "walk it on" by first putting the loose belt around the small pulley (about half way out on it), then place what you can of the belt onto the large pulley.  To get the rest of it on, manually rotate the drum (towards the part of the pulley which is not yet mounted) using the large pulley spokes as handles.  Don't worry too much about damaging the belt - they are tough.  But if it takes a lot of effort, the motor probably isn't pressed into the right swivel position.  Try pushing the motor up to relieve tension and try again.
3. Lining up the 13 mm bolt with the nut plate hole is hard.  Take a few tries, swivelling the motor just a bit and try again, threading it by hand till you feel the threads bite and go in a bit (1 turn if you're lucky).
12. Tension the belt by prying with a screwdriver until it gives a nice "twang" sound when plucked (quality beats quantity they say), then tension the 13 mm bolt fully.  It doesn't take much torque, but seems hard to break too so you'll be right.

Above I'm showing you what you won't see when you approach the machine from the back access panel.  This view is from underneath the machine.

UPDATE:  This machine was sold to us as "new but damaged in transit" seconds.  What they didn't tell us is that it had a refurbished brain in it, which had been damaged by a careless repairman.  So it was used.  Australian business ethics standards are a bit low.  The brain was bad, and the gel that the main PCB is embedded in had been damaged by the repair.  A new brain (MFS-AUJ2RC-00) fixed this washer.  It has 15 unique plugs (!) which you will need to reattach.  If you want to borrow a working motor to see if that is your problem, get in touch via the comments and you can use my leftover one.  If you can prove you have kids and use cloth diapers, I'll give it to you.