Washing machine door lock
 

I don't need help, but I'm writing this account in case it interests
or helps others.

I bought my Candy washing machinein 2011 because its front to back
depth is only 40cm whereas all other makes and models are 50cm. Ever
since new the door catch didn't always register as closed, and I had
to press the case slightly with my knee to make it register.

Recently I decided to do something about this, and removed the door
switch for examination. I found an adjustment screw that put variable
pressure on the spring contact arrangement, to make it snap either
open or shut. In one position, a plastic block stood 1mm above the
surface, and in the other the block was flush with the surface.

The door hook pushes a plastic slider across the block to depress it,
so I thought that the screw should be adjusted to make the block pop
up, otherwise the door would never operate it. Then it seemed that the
block was catching in the apertures in the slider, so I filed a slope
on the slider so that it could freely slide in and out, and either
allow the block to rise into an aperture or get pushed down by the
solid part of the slider.

This worked great - I no longer had to use my knee.

However the door lock indicator now showed that it had not been
released after the wash. It was no trouble, because the door had never
been locked anyway!

So I reinvestigated the switch. There are three wires into it. Two of
the wires go to the contacts, but did the third one that looked like
an earth do anything? I thought there ought to be some sort of
solenoid to act as a lock, but the switch is far too light for a heavy
solenoid.

The third wire went to the adjustment screw, which pressed on a
U-shaped metal piece cradling a thin metal strip by its ends. In the
middle of the strip was a white spacer about 7mm dia by 3mm thick,
which pressed on the switch. Now it dawned on me. The spacer is in
fact a 1K resistor, which can be heated by current, bending the thin
bimetallic strip and flipping the switch into the opposite position.

So the adjustment screw has to be set for the plastic block to be
flush when cold, not proud. When the machine is set going, the
resistor gets heated and the plastic block is biased up to be pressed
or not pressed by the slider. Throughout the wash the block stays
proud, preventing the slider from returning. Now I had to negate my
filed bevel by sticking on a shaped bit of tin to recreate the
original sharp edge of the aperture in the slider.

I tried a trial run with the switch out in the open so I could see
what happens to the plunger. Right enough it popped up at the start,
but didn't pop down afterwards when the resistor cooled down. However
a further adjustment of the screw made it pop down again.

I still don't know why I had to put my knee on it - perhaps the
adjustment screw wasn't quite set so the plastic block popped up
reliably, requiring a bit of distortion from my knee.

--
Dave W

Washing machine door lock
 

Dave W Wrote in message:
I don't need help, but I'm writing this account in case it interests
or helps others.

I bought my Candy washing machinein 2011 because its front to back
depth is only 40cm whereas all other makes and models are 50cm. Ever
since new the door catch didn't always register as closed, and I had
to press the case slightly with my knee to make it register.

Recently I decided to do something about this, and removed the door
switch for examination. I found an adjustment screw that put variable
pressure on the spring contact arrangement, to make it snap either
open or shut. In one position, a plastic block stood 1mm above the
surface, and in the other the block was flush with the surface.

The door hook pushes a plastic slider across the block to depress it,
so I thought that the screw should be adjusted to make the block pop
up, otherwise the door would never operate it. Then it seemed that the
block was catching in the apertures in the slider, so I filed a slope
on the slider so that it could freely slide in and out, and either
allow the block to rise into an aperture or get pushed down by the
solid part of the slider.

This worked great - I no longer had to use my knee.

However the door lock indicator now showed that it had not been
released after the wash. It was no trouble, because the door had never
been locked anyway!

So I reinvestigated the switch. There are three wires into it. Two of
the wires go to the contacts, but did the third one that looked like
an earth do anything? I thought there ought to be some sort of
solenoid to act as a lock, but the switch is far too light for a heavy
solenoid.

The third wire went to the adjustment screw, which pressed on a
U-shaped metal piece cradling a thin metal strip by its ends. In the
middle of the strip was a white spacer about 7mm dia by 3mm thick,
which pressed on the switch. Now it dawned on me. The spacer is in
fact a 1K resistor, which can be heated by current, bending the thin
bimetallic strip and flipping the switch into the opposite position.

So the adjustment screw has to be set for the plastic block to be
flush when cold, not proud. When the machine is set going, the
resistor gets heated and the plastic block is biased up to be pressed
or not pressed by the slider. Throughout the wash the block stays
proud, preventing the slider from returning. Now I had to negate my
filed bevel by sticking on a shaped bit of tin to recreate the
original sharp edge of the aperture in the slider.

I tried a trial run with the switch out in the open so I could see
what happens to the plunger. Right enough it popped up at the start,
but didn't pop down afterwards when the resistor cooled down. However
a further adjustment of the screw made it pop down again.

I still don't know why I had to put my knee on it - perhaps the
adjustment screw wasn't quite set so the plastic block popped up
reliably, requiring a bit of distortion from my knee.


Self isolating? :-)
--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Washing machine door lock
 

This design sounds a bit of an afterthought. My Panasonic has a solenoid you
can hear it quite clearly.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Dave W" wrote in message
...
I don't need help, but I'm writing this account in case it interests
or helps others.

I bought my Candy washing machinein 2011 because its front to back
depth is only 40cm whereas all other makes and models are 50cm. Ever
since new the door catch didn't always register as closed, and I had
to press the case slightly with my knee to make it register.

Recently I decided to do something about this, and removed the door
switch for examination. I found an adjustment screw that put variable
pressure on the spring contact arrangement, to make it snap either
open or shut. In one position, a plastic block stood 1mm above the
surface, and in the other the block was flush with the surface.

The door hook pushes a plastic slider across the block to depress it,
so I thought that the screw should be adjusted to make the block pop
up, otherwise the door would never operate it. Then it seemed that the
block was catching in the apertures in the slider, so I filed a slope
on the slider so that it could freely slide in and out, and either
allow the block to rise into an aperture or get pushed down by the
solid part of the slider.

This worked great - I no longer had to use my knee.

However the door lock indicator now showed that it had not been
released after the wash. It was no trouble, because the door had never
been locked anyway!

So I reinvestigated the switch. There are three wires into it. Two of
the wires go to the contacts, but did the third one that looked like
an earth do anything? I thought there ought to be some sort of
solenoid to act as a lock, but the switch is far too light for a heavy
solenoid.

The third wire went to the adjustment screw, which pressed on a
U-shaped metal piece cradling a thin metal strip by its ends. In the
middle of the strip was a white spacer about 7mm dia by 3mm thick,
which pressed on the switch. Now it dawned on me. The spacer is in
fact a 1K resistor, which can be heated by current, bending the thin
bimetallic strip and flipping the switch into the opposite position.

So the adjustment screw has to be set for the plastic block to be
flush when cold, not proud. When the machine is set going, the
resistor gets heated and the plastic block is biased up to be pressed
or not pressed by the slider. Throughout the wash the block stays
proud, preventing the slider from returning. Now I had to negate my
filed bevel by sticking on a shaped bit of tin to recreate the
original sharp edge of the aperture in the slider.

I tried a trial run with the switch out in the open so I could see
what happens to the plunger. Right enough it popped up at the start,
but didn't pop down afterwards when the resistor cooled down. However
a further adjustment of the screw made it pop down again.

I still don't know why I had to put my knee on it - perhaps the
adjustment screw wasn't quite set so the plastic block popped up
reliably, requiring a bit of distortion from my knee.

--
Dave W

Washing machine door lock
 

On 27/03/2020 21:08, Dave W wrote:
I don't need help, but I'm writing this account in case it interests
or helps others.

Excellent, thats the type of result I like to read about.
I just dont have it in me to buy a new part until I have tried to repair
it, more so if we are talking mechanical rather than electronic.

Washing machine door lock
 

Dave W was thinking very hard :
I tried a trial run with the switch out in the open so I could see
what happens to the plunger. Right enough it popped up at the start,
but didn't pop down afterwards when the resistor cooled down. However
a further adjustment of the screw made it pop down again.

They use a wax capsule/ plunger system on some door interlocks. Yours
sounds like one of those. A resister heats up a wax capsule, the wax
expands and forces out a plunger. Plunger retracts slowly, once the
heat from the resistor is turned off - so there is always a few seconds
delay between pressing the start button and the actual start, plus a
delay after the machine has finished, before the door can be opened.

Washing machine door lock
 

I think what irritates me is when a very firm metal design of say, a drawer
runner is fixed in with cheapo plastic brackets that sooner or later crack
and fall to pieces.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"ss" wrote in message
...
On 27/03/2020 21:08, Dave W wrote:
I don't need help, but I'm writing this account in case it interests
or helps others.

Excellent, thats the type of result I like to read about.
I just dont have it in me to buy a new part until I have tried to repair
it, more so if we are talking mechanical rather than electronic.

Washing machine door lock
 

On Fri, 27 Mar 2020 21:23:09 -0000, "Brian Gaff \(Sofa 2\)"
wrote:

This design sounds a bit of an afterthought. My Panasonic has a solenoid you
can hear it quite clearly.
Brian

Most other machines (including Panasonic) use the same or similar
switch. I assumed mine had a solenoid which I "could hear quite
clearly", but in fact the click was the switch popping down when it
cooled down, kicking the slider out on its spring.

I've now seen many articles on Google on how the switch works and how
to change it - I wish I'd seen them before tinkering with mine.

I did see a picture of an AEG lock that includes a solenoid.
--
Dave W

Washing machine door lock
 

Brian Gaff wrote:

This design sounds a bit of an afterthought. My Panasonic has a solenoid you
can hear it quite clearly.

My first two "british" Hotpoint washer dryers had an interlock based on
the drum rotation, you could open the door the instant the drum stopped,
now my "italian" Hotpoint makes me wait a couple of minutes before I can
grab a shirt in a hurry ... progress huh?