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Found this 8A fuse was seemingly the one I heard blow:
Maybe time to give up!
Yesterday I replaced the 750mA fuse, put a bowl of water in and turned on the microwave, it appeared to start as usual then something popped. I figured the fuse.
Looking tonight and the 750mA fuse has not in fact blown. Then, although it tested OK the capacitor appeared a bit swollen. It was 1.14uF.
Figuring nothing to lose, I replaced the cap with a good, brand new 1uF capacitor.
Plugged in and nothing. Now not even the screen lights up.
Morning, yes it’s a complete fitting. I broke the duff fuse trying to get the end caps off. I’ve cancelled the lose fuses I ordered and ordered instead the whole thing.
Note to self, save the fuse too the next time I come across a scrap microwave rather than just the trannie!
I’ll report back as and when.
OK, a bit of early morning meggering: I measured infinity between the magnetron casing and either terminal:
As aforementioned, across the same two magnetron terminals on the low resistance range I’m seeing nom 0.3 ohms.
electrofix wrote: prob ok but do it on a meg ohms scale before you go further
Dave
Thanks. As in “megger it” with an insulation resistance meter? Mine is an old 500V job.
“you have only measured the heater on the magnetron but now set multimeter on the highest ohm scale. one lead on either of the mags terminals and the other one on the metal casing. you should get no reading at all. if you get any mag is scrap”
Forgot to say I did that too, with the meter set on the 2K resistance range. No reading from either terminal to the metal casing of the mag.
Slight correction…
I read that a standard multimeter might not have enough forward voltage to check these diodes. Went and found a good 9V battery and like this got apparent continuity one way:
This big diode appears open circuit!
So I’ve found the duff fuse and diode any suggestions as to the cause?
Thanks
A little bit of investigating just now. All measurements with leads removed:
The capacitor measures nom 1uF
Across the magnetron I’m seeing nom 0.3 ohms.
Though the clear insulating boot on the red lead to the magnetron appears scorched, the actual connection doesn’t show any sign of overheating. Still a potential high resistance joint? I could solder it.
I have found though the 750mA fuse has blown!
[USER=”4209″]electrofix[/USER] many thanks for that.
Yes well aware of the potentially lethal voltages inside thanks. The day job involves safe isolation etc.
As I understand it, from some further reading since I posted, the (IF) suffix on the Magnetron dictates the mounting. I’ll remake that crimp as a first port of call. I wonder if another 2M253H could be got, taken apart and utilise the (IF) mounting from the original?
Thanks
Update: They’ve written the wm off and we get to choose a new one! As this was quite a high spec when we got it, 1600rpm rpm spin etc, be interesting what SWMBO chooses.
Update: A third engineer came and replaced a load of parts. Two halves of the drum, bearings, a shock, a spring etc. Did a couple of washes then on the 1600 spin the belt came off. Tried putting the belt on again but it just comes off on spin.
I’ve had a look and there’s a bit of casting missing off of the motor where it should attach to the drum.
Weird. I can’t find the piece on the floor or the bottom of the machine. Maybe it wasn’t there and he knew when he left?
Picture:
To update. I got the earth rod reading circa 20 ohms. 2nd engineer came back, checked the earth and commented “it’s not great” but then that he knows TT varies, he knows we have an RCD and that he was happy to work on it. Said if he was that worried he had a plug in RCD. He didn’t of course have the parts to fix the machine 🙁
3rd engineer attends. Checks and says the earth is fine, that he too carries a portable RCD. This one comes with the back half of the drum that the second one noted was required. Then says it also needs the front half too. Luckily he has one in the van for another customer but that it’s the wrong part for their machine. Lucky us.
Spends ages. Replaces a broken shock/damper, belt etc. Gets it going and leaves. Happy ‘ish wife though she said it sounds “different”. Does the first wash fine. On the second wash the drum stops turning, the belt has come off. I refit it, off it goes and comes off a second time a short while later. Fitted now for the third time with the belt dead centre of the 11 groove pulley on the motor.
We’ll wait and see!
I know the ribs of the belt should sit into the grooves of the motor pulley with the smooth side out. Is it though important which way round the belt sits?
I’ve sketched the belt profile. There’s 5 ribs but “1” is different to the rest and it’s not wear. All the 11 grooves on the motor pulley appear the same profile as 2,3,4 & 5.
The machine is a WMD960 and the belt is a 1613202002 5PJE 1158. Link to my sketch:
