Burnt out mains capacitor

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Burnt out mains capacitor Chrisy 07-01-2009
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Posted by Chrisy on July 1, 2009, 4:51 am
Hi there.
This looks like a great newsgroup.

Husqvarna Optima 150

We have burnt out an AC capacitor in our old Husqvarna.
What we wanted to know is if it's alright to continue using it with the
cap removed, at least till we can find another one?

Is it just a RF suppressor, or is it to stop arcing within the foot
pedal and motor brushes?

On the cap it says:

Front:
RIFA
40/085/56 GPC
PME 271M 610
CP9

Top:
0,1uF@X

Back:
fo=4,9MHz 250V~MP
565-1ALD2

There are some other symbols on the back that despite looking up special
symbols tables, I found no way of reproducing. But I think there is
more than enough information there anyway. (:

We couldn't find much in the way of caps in Australia so
would one of these do the trick? The direct link to the page is way too
long, so I had to use tinyURL to create a link, sorry.

This is the home page, just in case your wondering.
http://www.dse.com.au/cgi-bin/dse.storefront/
This is the tinyURL link to the high voltage capacitor page.
http://tinyurl.com/l2bh4n

Any help with this will be greatly appreciated.

Cheers.
-Chrisy

Posted by Alan Dicey on July 1, 2009, 7:14 am
Chrisy wrote:
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I'd say probably not. This machine has electronic speed control, and
this component could easily be part of the control circuit, not just a
transient supressor.

Having refurbished components on an Elna TSP Air Electronic circuit
board (which required me to reverse-engineer the circuit diagram), I
would say that it's not safe to assume that this capacitor is just a
mains supressor
show/hide quoted text

I can translate some of these
show/hide quoted text
Manufacturer, Evox Rifa

show/hide quoted text
40/085/56 - IEC Climatic category: 40°C, 85% rH, 56 days

show/hide quoted text
Manufacturers item code

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0.1 microFarads, the capacitance of the device.
X - Classification of capacitor,international standard. Intended for
use as interference suppressors across the power input. That doesn't
mean that it can't be used for something else, of course.

show/hide quoted text
fo=4,9MHz - self-resonance frequency 4.9MHz
250V - 250 volt rated voltage
MP - Metallised Paper, the construction materials

show/hide quoted text

show/hide quoted text

These are likely to be the various standards markings indicating
certifications and approvals the device complies with.

The capacitor should look a lot like this one:
https://www.wellgainelectronics.com/index.asp?PageAction=VIEWPROD&ProdID=2985


show/hide quoted text

Your tinyurl isn't working for me.
From the supplier you've chosen, I'd go for this component, which will
replace your burned-out example
http://www.dse.com.au/cgi-bin/dse.storefront/4a4b297e15c34ce22740c0a87e0106b9/Product/View/R2628



Posted by Chrisy on July 1, 2009, 9:33 pm
Alan Dicey wrote:
show/hide quoted text
http://www.dse.com.au/cgi-bin/dse.storefront/4a4b297e15c34ce22740c0a87e0106b9/Product/View/R2628
show/hide quoted text

Thank you so much Alan for the link and the great advice.
Imagine how much the shop would have charged us to replace one cap.
Probably about $70AU (approx £35) would be a fair guess.

Dick Smith want $0.95 for the cap plus $9.95 for P&H, so you've saved us
around $60! You've really helped us out a lot.

I never realised how many amazing things capacitors are used for till I
started to look into it yesterday. You must really know your
electronics. It was the use of a comer instead of a full stop as a
point symbol (0,1uF) that confused me. I didn't know if it meant 0.1 or
1 uF, but I guess 1 Farad must be quite a lot. Some of those larger caps
sound quite dangerous.

The tinyurl link didn't work here either. I had to find and install the
add-on and now I don't know why I bothered. Maybe tinyurl.com is a
blocked site in my hosts file.

Anyway, cheers for that Alan, it's very much appreciated.

And being and Aussie Sheila I guess I better say it just for a laugh.
show/hide quoted text

-Chrisy


Posted by Alan Dicey on July 2, 2009, 4:00 am
Chrisy wrote:

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The shop would charge for the labour involved in removing and replacing
the circuit board and the component. Maybe 30 minutes to one hour.

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The postage seems a lot compared with the component price. Maybe its
worth skimming Dick Smith's catalog for anything else you might need -
tools, solder, adhesives, CD/DVD-ROMs, cases, that sort of thing.

In the UK I am lucky that there is a supplier that maintains a physical
presence, real shops you can visit. Maplin Electronics has two shops
within a 30-mile radius of here. Tandy/Radio Shack used to have a shop
even closer, but they have closed down in the UK - however they still
appear to be alive in Australia, so it may just be possible there is one
close to you. Whether it is within AU$10.00 worth of petrol is a
separate question :-)

In Australia I expect that distances between towns are larger and useful
shops less widely distributed. I can find other online suppliers,
though, Jaycar, Altronics, Farnell Australia and RS Components
Australia, should you need to shop around in the future.

show/hide quoted text

The use of a comma for the decimal place is standard practice in
continental Europe. Rifa is Swiss-based.

Capacitors are charge storage devices, and large devices can store
enough to give a startling shock. One Farad would be a large
capacitance, and I've never seen a single device that large. In the few
applications where they are necessary they are built up from banks of
smaller devices.

The biggest danger from larger capacitors is explosive decomposition
from putting AC across them. Larger capacitors are polarised and can
only be connected across a load where the DC component is larger than
the AC ripple. Going negative will result in a fountain of hot paste
spitting out of a safety vent in the lid of the can.

Anything can be dangerous if handled carelessly.


show/hide quoted text

No problem. I assume that you or someone nearby is confident enough
with a soldering iron to swap out the dead component.

I'd be careful to check the machine for any other damaged components,
resistors showing signs of overheating or capacitors with bulged cases.
When I refurbished Kate's Elna, the root of the problem was a
burned-out resistor, the capacitors had just aged and bulged from
overheating. Metallised Paper capacitors are known to deteriorate with
age. It may be worth replacing any other such devices on the board.

http://www.diceyhome.free-online.co.uk/StellaTSP_Electronics_refurb/Stella_refurb.htm

Careful not to overheat the board while soldering or desoldering,
especially if close to any active devices (transistors, integrated
circuits - generally anything with three or more leads). Also, the
printed circuit tracks can lift off the surface if overheated. A
desoldering pump can be helpful.


Out of interest, can you post pics of the board, showing the burned out
component, if you have a digital camera?

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The UK. Same house as Kate :-)

Posted by Lizzy Taylor on July 2, 2009, 7:17 am
Alan Dicey wrote:

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Ah yes, the yellow stinky stuff. ;-) DH not me - it stains too, much
like ferric chloride.

Lizzy

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