MINI PAS pump PCB question

[elebub]

Hi

Common fault on 1st generation BMW MINI electric power steering pumps - dust from the brushes finds its way into and onto the controller board and causes the pump to fail. Stripped it down and found the blue plastic coating coming away from whatever that is in the pics. Is this of concern and if it is, suggestions for a remedy would be much appreciated.

Cheers

Andy

 

[pedrobedro]

It looks like it is failing, that's what happens to capacitors when they break down inside and swell up. The only remedy for it is replacement with a new one usually. I'm not an expert but I have seen fail them on motherboards and that's what it looks like to me.

 

[zx9]

I agree with pedrobedro, looks like a failing capacitor, as most of the small and delicate components are on the other board it should be easy enough to change the cap.
I would have hoped that EPS would be designed to last a little longer.

 

[elebub]

Thanks for the replies. Is there anyway of testing it with a multimeter while it's on the board?

 

[zx9]

No not really the other components will influence any tests, given how swolen the case is I would just order a replacement, it should say how many microfarad and max voltage on the side, should not be more than two or three quid.

 

[normspanners]

I would change them all whilst in there, if one's gone the others may not be far behind.

 

[elebub]

Thanks for the advice I will do as you say. Can you point me in the direction of a good supplier? I know I can Google it but a recommendation.........

 

[the snooper]

maplin amongst others will have them

farnells, cricklewood electronics and a load more

 

[rikrobson]

Its an electolytic capacitor. looks like its got hot and will have dried out.
they have a capacitance and, a voltage and a temp rating.

the capacitance must be correct, but as long as the voltage rating is at least what you are replacing it will be fine. Also they are polorised, so you must ensute that its is fitted the correct way round (they go pop is fitted wrong)
They will ge about 50p to a £1 in maplins depending on the type

they will probably be 16V but maplins do a decent range 25v (105C).
at a guess they look like 2200uF

89p from maplins

 

[elebub]

The markings are: BC 125°C 165 KO 2700u-M 25v
The two nearest the plastic plugs are marked R3 and the other two are marked R4

I have measured the diameters and they are all the same with no outward signs of swelling or damage?

 

[ben8vgte]

The "u" is the microfarads rating so it's 2700uf 25 volts, the only go in one way round. So one side should have a stripe to mark the negative side.


I find http://www.rapidonline.com/ cheaper than maplins most of the time.

 

[bump]

Another victim of Chinese Capacitor Syndrome (Google it for the financial damage it has inflicted on the likes of HP, Cisco and Dell). As said, swap it out and you'll be fine. I would change them all whilst you've got it stripped down as I would expect all the rest will go the same way soon.

Strangely I didn't think of automotive being a victim. Must be spending too much time around computers.

 

[elebub]

Is there any significance in that two caps are marked R3 and two marked R4?

 

[bump]

Those are more than likely markings that relate to the schematic drawing. As long as the values are the same as the replacements then nothing to worry about. R is usually used for resistors and C for caps. May be a German thing though.

 

[cracker666]

To check caps you need a ESR meter to check it, as even if it looks ok they can still be bad.
I have such meter a esr70 and repair pcs screens etc.

 

[cracker666]

Remember to discharge them as these store charge

 

[cracker666]

R a followed by a part number are for the assembly line, so they can check them.

 

[Wedg1e]

Remember to discharge them as these store charge

Won't be an issue at 12v You might get a little spark but it's not going to blow anything up or electrocute you.

 

[Wedg1e]

Usually when electrolytics split their plastic sheath it's because they've got hot... but that doesn't automatically mean the thing will have gone phut or outside tolerance.

Even so, as you've got the unit stripped that far, it'd be false economy not to change them.

Shocking bit of design if someone didn't allow for conductive dust mixing with a microprocessor circuit

 

[Shox Dr]

Shocking bit of design if someone didn't allow for conductive dust mixing with a microprocessor circuit

But how would they sell you another one if they did that.