Hi All
Used to watch U-Tubes from time to time and I noticed that Dave managed lots of times to source diagram for various even older item.
I had no such luck with my sewing machine.
Part that blew up looks like kind of EMC/RMI suppression.
Is placed as first thing past ON/OFF switch between active and neutral of 240V power source.
From part I got some info:
100n x2
PME 285MB
40/100/56
RIFA CW5
On the other side there are several what looks like country symbols plus 250V SH
When I search all or some of this, unfortunately nothing comes as part for sale
Made couple of not so good pictures, but have to work out how to post them.
Thanks for any help
Much appreciate your help.
This is good start:
Important parts: Mains rated (250V), 100nF, Class X2.
Is there another substitute that would be bit better?
Something like higher voltage or more nFarads?
There's nothing wrong with these values. It is as you found yourself just for basic filtering / suppression. The machine will probably work without it.
Normally the capacity in these things does not really matter for the device to function. So I just stick to the values they got in there originally or something near that. Voltage rating is of course important but AFAIK these caps are only made mains rated or higher. But this is not the factor that kills them! The X2 class sais it can handle spikes of at least 2.5kV. Class X1 would handle up to 4kV if that is important for you. Whats more important is the fact these caps are not polarized and do not start to burn if they die. But at least older ones do often short then, which leads to malfunction. Funny: Last one I replaced was in a footpedal for a sewing machine. The machine would run all the time as the resistors and switches in the pedal were shorted out.
Edit: Start here for more information:
http://en.wikipedia.org/wiki/Film_capacitor#Safety_and_EMI.2FRFI_suppression_film_capacitors
Grab any old PC power supply and you will find them in the case where the mains connects to the board, assuming they were fitted and not left out as a cost cutting measure. Unsolder and resolder in place on your board and it will rise from the dead like Dr Fankenstein's creation.
Yes, forgot to mention that! These caps are in nearly everything that has a switching PSU. So they are easy to find and rip out.
Most appreciate fantastic help.
Thanks to Dave's LCD monitor U-Tube I saved my Samsung 20" LCD monitor with $7 worth capacitors.
And now looks that my Husqvarna sewing machine will get second life too.
On JayCar web site found those (15 mm spacing is exactly what is needed)
for under $1 Australian.
Is it adequate replacement? :
250V AC Mains - Metallised Polypropylene Capacitors - X2 100N
Volt Rating: 275/250VAC
Capacitance Tolerance: +/-10% std +/-5%
Operating Temperature: -40°C to 85°C
Value = 100N
Lead Spacing = 15mm
So hardly need for sourcing one for free.
Love that polarity is not important, not that I cannot keep an eye on this, but it gives extra stress.
Also will try to desolder failed capacitor and try sewing machine without it.
Big thanks again !!
Trying to include picture
(White part is blown capacitor)
Yes, you can use the jaycar one. Every important rating is the same, so no problems there.
Schwarz-brot
Thanks for help.
On Wednesday will have time to get it.
Out of curiosity I removed the burned out capacitor ( as I did not have guts to try machine with it still in place )
And machine started OK
Didn't want to push my luck and sew something before I get replacement.
Will have to read more Wiki to find out significance/importance of this capacitor, and what it prevents or what it helps.
So many things I don't know !
Probably should not waste EEV Forum bandwidth, but would like to tell about my success story, thanks to your help !
Got part RG5236 at JayCar:
250V AC Mains - Metallised Polypropylene Capacitors - X2 100N
Installed in place of failed one and my Husqvarna Sewing Machine is up and running.
Once again very big thanks for help !!
You're welcome!
Glad to hear you brought it back to life. Repairing is always better and more satisfying than getting something new
Sorry to bother you all, but sewing machine works well,
so happy.
Hello!
I've got exactly the same machine second hand and the day I plugged it in was working fine for about 5 minutes and then, suddenly, I heard a strong sound and it started smoking white.
When I opened it I saw I've got the same problem as you!!! I was so glad to find this post!!! So I replaced the piece following your instructions but the machine refuses to work now
(((
The light still works so it means it gets power...I'm scared is the engine ;__; ...but I dont know how to check if the motor works or not... any advise??? I join some photos that I did the day I opened it the first time now the white piece has been replaced.
thank you very much, any help will be apreciated
Raquelmpq, that white capacitor is very likely connected across the AC mains input to the electronics board. In the other posts above, apparently when the cap failed it did not blow the mains fuse on the circuit board. That's the little metal and glass cylinder just behind the cap in your photo. Maybe yours did blow that fuse? You can tell by looking at it - is the wire inside intact? Can't tell from your photo.
I'm guessing from your post that you are not much into electronics and found this thread & forum via google?
Not a problem, just need to know how best to help. Do you have a way to post pics that are clearer?
Why is the photo posterized into so few colours?
Ah, I think the forum software has compressed it because the XY size in pixels is so huge. It's 3,264px × 1,836px.
If you can reduce images to something like 1000 x 800 pixels before uploading, they will look much better.
Hi! Thank you for your answer
and yes, I have no idea of what I'm doing I just follow the instructions to solve what it seems to be the problem XD
The fuse seem to be OK, I guess the burn is from the capacitator (photo attached) but I'll try to change it to see if like that the machine works.
So, do you have a soldering iron? Or can borrow one?
To remove the blown white cap, you don't need a solder sucker, just the iron. Put finger pressure lifting one end of the cap upwards away from the PCB, while you melt the solder on the pin under that end. Helps if you can hold the circuit board in something as you do this, unless you have a third hand/helper. The cap will lift a little bit. Switch to the other end, do the same, it will lift a little more. Repeat, going back and forth, and the cap will come free after about 3 cycles.
You can clear the holes of solder by poking them with a toothpick while melting the solder with the iron.
Try to keep all the solder-melting time to a minimum, or the heat can make the copper track separate from the PCB. But it's not a disaster if it does, as that can be fixed with a little bit of wire.
Once you get the burned cap out, clean as much as you can of the mess off the nearby parts. Methylated spirits and a tissue will do.
Are you sure there are no other fuses? There might be one in a pop-out holder at the mains cord entry socket on the outside of the machine. If not, do check the circuit breaker for that power point didn't trip. Plug a lamp or something else into the power point to check.
Also, can you post a photo of the other side of the circuit board for the area you showed above (and a bit more around.) So we can check that cap, fuse etc are really what we thought.
Picture shows that your white capacitor blew open.
Interested if you made machine to work again?
Hi, could you post a photo of the bottom-left area of the PCB (with reference to the photo attached) clearly showing the two resistors left of the BC547 transistor? I've been asked to repair a 120V variant of the board that someone accidentally put 240V into, which blew the MOSFET and fried the resistor under the 150R (brown-green-brown-gold) one as a result. Unfortunately the value of the latter can no longer be read. Note the photo was taken after it had been desoldered, so it's not present.
It seems the resistor was a 680R looking under the microscope. The BYV28-200 ultra-fast avalanche sinterglass diode also needed replacing (went short circuit). The 1N5402 rectifier diodes around the 22uF 250V cap, BC5xx transistors, BZX79C12 12V zener, 150R resistor and 220uF and 2.2uF caps were also replaced due to age/just in case power rails exceeded their ratings. Tested and working again!
