why does my makita go pop occasionally ?

Here you go....

Is this any good?

https://www.partshopdirect.co.uk/makita-noise-suppressor-240v-mt811-p645195-8/

Bear..

Hi Grizzly and thanks for your input. Well it looks closer, in terms of a parts diagram matching with the reality. Can I ask what took you here ?

I suppose I may have to give it a try and find out.

Gerry.

I'm pretty sure that the 'yellow thing' is a mains suppressor, comprising three capacitors in a delta network, and it's certainly the culprit. The second line of print on it (obscured at the start) is probably decoded as '1 off 150nF and 2 off 2.5nF'. It's followed by a 'Y', which presumably identifies the capacitors as Y-Class. 3-capacitor delta suppression networks are used all over the place, made by many manufacturers, and available from places such as RS Components. Cheap. Component values won't be critical. No need to hunt for a 'Makita' one, just get one around the correct values (there won't be much choice) and a suitable physical size. And search the 'net for delta suppressor capacitors or similar, for more info.

One leg to live, one to neutral and the third to ground (earth). The spring will just be the ground lead's connection to the motor's earthed frame.

Incidentally, these days, X- and Y-Class suppression caps are usually metallized polypropylene, and fail in a dignified manner (if at all). I have replaced several older metallized paper suppression caps which failed with smoke, flames, bangs and a disgusting smell. Before the fireworks, they often swell, so there's sometimes some warning. For some reason, they are still available. Description in a 2013 RS catalogue contains 'high safety regarding active and passive flammability due to metallised paper construction'. Diametrically opposite to my experience! They seem to last about 20 years - well out of warranty, so who (except me and thee) cares?

Edited By Kiwi Bloke on 26/01/2020 10:12:40

Me too. VDE 565.1 is a quality mark covering interference suppression devices.

I don't recognise the seem or feem trademark, so I guess the suppressor was made in the distant past. 25/065/04 is the climatic code (Can't find a decode table but it covers the suppressor's normal operating condition: arctic, tropical, temperate etc.) That the suppressor doesn't carry any of the modern codes such as EN60384, or UL1414, or GBT/T14472 also suggests it's at least 15 years old. Time for a new one! Provided it will fit in the available space, almost any UK mains rated Y suppressor will do. As it only costs a couple of quid, Bear's find is surely worth a punt.

Dave

It would seem odd to have Y-capacitor suppressors when there's no earth connection?

Andrew

KB thanks for excellent and informative info and to SoD for confirmation. I'm on the case now following Grizzlys suggestion.

Its satisfying to keep these old machines going using skills knowledge experience and of course the internet.

Regards,

Gerry

Hi Gerry,

Regarding the 'search' duckduckgo, "Makita mains noise suppressor."

It gives you some insight to suppressors in general.

Interesting comment from Andrew, regarding earth (Ground) connection.

Good luck!

Bear...…..

Earth connection to the motor, done that way to speed assembly? I'd prefer a nice bolt!

As far as I can see the yellow thing has 3 wires, which I'd expect to be L, N and E on a simple suppressor. It's not a filter. Inside, capacitor across L and N, capacitor from L to E and another from N to E, the whole lot wrapped in silver foil as a screen which is also connected to E.

Dave

'Its satisfying to keep these old machines going using skills knowledge experience and of course the internet.'

Absolutely! Save the planet! Join the Right to Repair movement!

Just to tie up a few loose ends about these things, for anyone who's interested...

These three-leg capacitor networks comprise one X-class capacitor connected L-N and two, equal-value, Y-class capacitors, one L-E, t'other N-E, hence the 'delta' moniker. X-class caps are designed to fail by going short-circuit. This should blow the supply fuse or breaker, alerting one to the fault and rendering the device 'safe' - i.e. unpowered. Y-class caps should fail open-circuit. If failure were by short-circuit, the frame of the device would be connected to the mains live or neutral - not desirable.

I've looked in a couple of catalogues and am surprised to see many such devices are of metallized paper construction. Given my experience with this construction failing, I'm surprised. However, dredging through the memory banks, I think the failures were all of the same make, so perhaps metallised paper per se is OK, but 'my' caps' manufacturer was the culprit. I note that above I've said '...designed to fail...': I wonder...

Possibly less stringent testing for the requirement to fail open, but it would seem unlikely to design for failure to be a short. What happens if the shorted capacitor doesn't blow the fuse? You burn to death rather than get a shock.

Andrew

OK, perhaps it's more correct to say that X-class caps are allowed to fail short, whereas Y-class must not and are designed accordingly. The message is that one should choose the correct class of cap if replacing caps connected to the mains, i.e. X-class between Live and Neutral and Y-class between Earth and either Live or Neutral. Be careful!

As per Grizzly's suggestion, a new capacitor was obtained fitted and all is well. Checked the old one. No leakage on the Ohmeter but a physical stripdown confirmed damage.

Thanks all for your inputs.

Gerry

Glad you got a solution to the problem Gerry.

regards