WT640 Controls

Repairing a Hotpoint WT640 With The Flashing Display Fault

Note : This involved opening up mains powered equipment. This is dangerous and if you don’t understand and feel confident in what you’re doing don’t do it!

Due to the amount of sharing of components this may well apply to other Hotpoint models or even other brands (such as Whirlpool or Indesit) as they are all part of Whirlpool Group but this is the machine I had and did the repair on and beyond that don’t know. Anyway, back to the point…

So one day I went to my washing machine expecting it to have finished and it’d stopped mid way through a cycle and the LED display which shows the remaining time was flickering badly. I turned it off and on again and it worked and the screen came on as normal so initially I wrote it off as just a blip and carried on my day. Unfortunately a few days later I turned it on and the problem had come back and this time I couldn’t get the machine to run a cycle and powering off didn’t help.

Knowing there’s not much going on inside a washing machine from a technical point of view and also knowing that flicking/buzzing on equipment is often caused by a capacitor failing I decided I’d have a quick look and see if I could find any of the tell-tale signs of capacitor failure anywhere.

Before you do anything unplug the machine!

The main PCB for this machine is located to the rear of the machine behind a hatch and once you can get at the back of the machine is really easy to remove.

WT640 rear access hatch

First off remove the white hatch on the rear of the unit as shown in the photo, this will require a crosshead screwdriver.

WT640 Main PCB location

Looking through the uncovered hatch you will now see the PCB to the left hand side with a number of connectors installed in it and the wiring held in place by clips. Gently release the wire from the clips so it is free to move. I suggest taking photos of how it is all laid out so it’s easy to put it back later. Next remove the screws in the rear panel that retain the PCB housing (highlighted in red below). You may also still have a cover over the diagnostic port (location marked in green) and if you pop this off as well.

WT640 PCB housing mounting screws

At this point you should be able to lift the PCB out of the hatch. The wiring is still connected currently but should have enough slack to allow this.

WT640 Wiring positions

Now gently pull off all the the connectors and you can remove the whole board from the unit. This is the bit where many maintenance/service places will just plug a new board in and call it a day but that costs quite a bit of money and not the sort of thing I do given half a chance!

WT640 Main PCB removed from machine

Next there are a series of clips around the plastic housing that we need to undo separate the housing and look inside. You should be able to release these by just squeezing the lower section of the housing but if not slip a fine bladed screwdriver between the sections of the housing and pop them apart. The position of the clips it pretty obvious because there are matching cutouts in the plastic. The image shows one side but they continue round the casing.

WT640 PCB cover clips

With any luck you should be looking at something like this:

WT640 Main PCB Open

Now there’s not a lot of parts on here but a very brief search leads us to the small group of capacitors in the centre. Specifically the parts marked on the PCB as C17 and C20.

Capacitor failure signs on C17 and C20

Looking at these capacitors it’s pretty easy to see both the 680uF (C17) and 470uF (C20) have swelled out end caps which is indicative of failure so that’s a strong indication this is a problem and while there’s no guarantee it’s the cause of the specific problem we are having it’s a pretty strong possibility! For the sake of a couple capacitors it’s well worth replacing them regardless and seeing what happens – so that’s what I did.

The pads to desolder for C17 and C20

I’m the image above I’ve marked the pads that need de-soldering to remove these capacitors just to make life a bit easier. You can probably see that I’ve put red sharpie on them in the image as well – this is something I often do to make sure I don’t try to desolder the wrong part.

C17 and C20 Capacitors removed from the PCB

So now the dodgy capacitors are gone, check the markings on yours and order some replacements. Mine were both 10V rated electrolytic parts rated at 680uF for C17 and 470uF for C20. When ordering capacitors the voltage isn’t critical as long as you’re buying ones with a voltage either equal to or above the required voltage so in this case you could use 16V or even 25V parts if they’re easier to get. I recommend buying a higher temperature type (generally 105°C parts are widely available and will make the component last longer) additionally low-ESR parts have less of an internal heating effect and so if you can get these do so and they should last even longer, particularly in warm environments. You could just do like for like replacement but I’m a fan of doing a bit more to only do a job once and not have to fix it again later. Particularly when the parts are so cheap! Make particular note of the polarity of the new capacitors when you install them, the polarity marks should be the same way round as the old ones.

New C17 and C20 capacitors installed

The new capacitors are installed. Now in classic Haynes manual style “reassembly is the reverse of disassembly”. Once I’d stuck everything back together I put the power on and the blinking was gone.

Good luck, as ever your mileage may vary!

Update : Two years later it’s still working perfectly.

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