Moulinex Motor/Main Capacitor

[SeanStevens]

Hi everybody,

I took this tiny coffee grinder apart as there was a rattle and general looseness to the unit when handling. I'm glad I did as I'd consider it has got a little unsafe.

The capacitor (I think it is a capacitor) has very tired wire insulation and I though I'd replace the insulation. Seeing as this is about 50 years old I guess it would be prudent to replace the capacitor.

It has 107 printed on the red insulation - I'm guessing that is 100 μF, so I probably need a 400v 100 μF as it appears to be across the motor.

The case is earthed - so is this possibly two capacitors in one?

I'll attach a photo in a moment


SEAN

[paulsherwin]

100uF is extremely unlikely. It's probably 2 low value caps to suppress interference. The simplest fix is to remove it and fit a class X2 across the mains, or a class Y between each connection and earth. Nothing will be very critical.

[SeanStevens]

Photos as promised

[SeanStevens]

Originally Posted by paulsherwin

100uF is extremely unlikely. It's probably 2 low value caps to suppress interference. The simplest fix is to remove it and fit a class X2 across the mains, or a class Y between each connection and earth. Nothing will be very critical.

Many thanks Paul,

I'll see if I can measure what values it has when next at Ian's as he has a device for such things. I wonder if they make anything in the same shape/encapsulation any more?

SEAN

[Lucien Nunes]

If there are three connections - two leads to either side of the motor and a third, possibly via the case, to the motor frame, then it is a delta capacitor. Two class Y caps of a few nanofarads from each live lead to the frame and a larger class X one of tens or hundreds of nanofarads across them.

They are available in the same format, not sure how close the size will be.
E.g. https://www.tme.eu/gb/details/ksppzp...a12nu410m254m/

Search for '3-lead suppressor' or filter capacitor or similar.

Note that if the grinder is class II (no connection to earth) and there is not double or reinforced insulation between the motor frame and the user, then the caps to the frame must be class Y and limited in value because they are part of the insulation between the live parts and the user. There are larger units of the same basic design but with larger value capacitors where the middle wire is connected to earth on class I appliances

[SeanStevens]

Many thanks Lucien,

I'm hoping the value of the capacitor will be evident by testing - but that capacitor in the link looked good. Unfortunately that company is not accepting new customers because of Brexit!



It is a two wire (no earth) appliance and the motor is not double insulated as far as I can tell. I'll hunt around when I have more idea of values, but thanks, I'll hunt for:
X2/Y2 polypropylene capacitors

cheers

SEAN

[Lucien Nunes]

I would not worry too much about the value, it's just an RF bypass for interference from the brushes sparking. You probably won't get any choice when you buy the replacement anyway, indeed some sellers don't even bother to quite the value, it's just a suppressor.

However, if you try to measure it as a 2-terminal device, the X-cap reading will be about right but you will read the two Y-caps almost in parallel due to the larger X-cap, so their true value will be half the reading. An unnecessarily high value will increase the touch-leakage at the metal parts and is not permitted.

[paulsherwin]

If it's double insulated with a 2 wire mains lead then I wouldn't worry too much about this. Just wire a 0.1uF X2 across the supply. Actually, it should work well enough for occasional use with all suppression removed, though it may generate interference, particularly on the AM bands.

[Uncle Bulgaria]

Is that a Moulinex 505? I had a thread on one some time ago as after repairing corroded switch contacts I was not convinced by the spindle seal arrangement. If it is, would you mind posting a photo of the seal so I can see if my one is missing something?

[Graham G3ZVT]

https://www.vintage-radio.net/forum/...d.php?t=176541

[peter_sol]

It looks like 104 to me which is 100nf or 0.1uf.
A 400v AC type would do.

[SeanStevens]

Originally Posted by Uncle Bulgaria

Is that a Moulinex 505? I had a thread on one some time ago as after repairing corroded switch contacts I was not convinced by the spindle seal arrangement. If it is, would you mind posting a photo of the seal so I can see if my one is missing something?

No, this is a 228-2-00 model 140 watt

I cannot get the propeller blade off to see a bearing, but it was so full of old pepper/coffee in there I guess there is not dust bearing!

SEAN

[Maarten]

Originally Posted by peter_sol

It looks like 104 to me which is 100nf or 0.1uf.
A 400v AC type would do.

Normal 400VAC capacitors might be rated for no more than 630VDC, which makes them unsuitable for mains applications. If you don't want to or can't use an X2 rated type which is explicitly constructed for use across the mains (usually marked 275VAC, 315VAC or something similar, but with a much higher allowed peak/DC rating), you'd need an 800VDC rated capacitor or preferrably higher. It's cheaper, easier and safer to just use a good brand polypropylene capacitor with the correct X2 and/or Y2 rating. Y2 being the rating for mains-to-earth or mains-to-exposed parts applications, with an even higher dielectric strength and some sort of guarantee it will fail open instead of open or short.

[SeanStevens]

Thanks again all

Here are my findings when I measured the capacitor

Wire 1 to case - 0.08nf
Wire 2 to case - 0.06nf

Across Wire 1 and 2 - 25nf



I purchased a mains rated 0.022uF polypropylene
and two 2000v 100pF radial capacitors

As this unit only ever gets used in short burst - 5 seconds a day, perhaps twice, I though they would be acceptable.

SEAN