Hotpoint WM52 Washing Maching: slow start or no start!

[Davros28]

Our WM52 has developed a strange problem the logic of which defeats me!

It typically takes 10-20 seconds after switching it on before it actually starts, and during this initial "dead" period it just sits there in total silence and with the "Door Locked" indicator unlit. Nevertheless, once it has started, it happily completes whatever wash program that's been set with no strange noises or further unexpected delays.

More recently though, it occasionally doesn't start at all, even after the 10-20 second period. With it in this state, I've proved with a meter that power is applied to the control board/timer, but without the benefit of a wiring schematic, its difficult to fault it down to a specific component within the WM52. What generally happens is that we unplug the machine, wait 5-10 minutes, and then try again. This "second attempt" at starting the machine is usually successful.

Any pearls of wisdom as to the probable cause of the slow-start/no-start symptoms would be much appreciated.

 

[pto]

hi
its the door interlock common prob

Jack

 

[Davros28]

hi
its the door interlock common prob

Jack

Thanks for the info Jack.

Focussing on your suggestion of the problem being within the door interlock component, I tried the following test. With the door deliberately left open, I set a program, switched the machine on and then closed the door firmly. To my surprise the machine then started immediately. This suggests to me that the delayed-start/no-start problem is related to door-closed proving contacts (or microswitch) within the door interlock component.

Previously, I'd dismissed the possibility of the problem being related to this component simply because when I had got the machine to run, banging the door in the area of the mechanism never caused the machine to stop running or even falter. Perhaps the controller board doesn't bother to check the status of the door-closed proving contact after the machine has started but just relies on the interlock to prevent the door from being opened.

Am I on the right track with this assumption?

My local parts supplier didn't have a door interlock in stock today but I'll change this component just as soon as I can get a replacement.

Thanks again.

 

[pto]

HI
get it as soon as or the timer will suffer they are only £5 or £6

Jack

 

[Davros28]

Hi Jack,

You were absolutely right about the cause of the slow-to-start/no-start problem with my Hotpoint WM52P. Got the replacement door interlock today and after fitting it all was well with the machine.

Out of interest, I took the old door interlock (a Tip ZV-445) apart. I hadn't previously realised that it was of the bi-metal strip type. Its failure was due to the heater circuit between "L" and "N" terminals having become very intermittent. Still it hadn't done too badly since it was of 1997 vintage.

With the old interlock taken apart, it was clear that my previous assumption about its contacts (between "L" and "C" terminals) only proving the door as being closed, was wrong. Its now apparent that the contacts only "make" when the door lock is engaged which, because of the locking pin arrangement, should only be possible when the door is actually closed.

Hence the heating of the bi-metal strip causes it to push on the door locking pin and, if this successfully engages, also operates the single set of "make" contacts. Closure of these contacts indicate to the controller board/timer that the door is both closed and locked, and hence the machine can be started.

Out of interest, there is still a short delay before the machine starts (about 3-4 secs). This must be the time it takes for the bi-metal strip in the door interlock to heat up and close the contacts. Indeed, the wife says the machine had this sort of start delay when it was new.

Thanks again for your expert guidance.