Hi guys I need to replace a blown capacitor in a project but I cannot identify it.
Sadly the text is hard to read but i have taken a high res slightly photoshopped photo to bring it out a bit more.
Can anyone help with which number will point me in the right direction? I can only gather that it might be a 1u cap.
Thanks for any help
Krish
u1 strongly suggests 0.1uF.
What kind of circuit is it in?
It's a dipped film cap. 630 makes me think it might be rated for 630V.
As Mark asked what circuit is this in?
The good news is that in most applications, the capacitor value is not too critical. Usually a higher value is OK. And a higher voltage rating is always OK. (As long as the replacement part fits mechanically.)
If the capacitor is shorted (you can check it with a multimeter after removing it), some other components may be dead too. 
So you can probably experiment (after measuring the voltage, or making some estimation of the voltage based on the circuit design/application). The wrong value capacitor isn't going do any more damage than has already been done.
It's odd though... I don't think I've ever seen a film capacitor burn-up! And usually when an electrolytic or tantalum "blows" it's been installed backwards or it's the wrong part with an under-rated voltage.
This one got blown due to idle solder wire which I did not spot and which shorted some part of the circuit.
The circuit is a motor control board which handles both the power supply and PWM operations. I have included a pic as well as the location of the short.
The resistor and also the small orange components (another cap?) have also been blown.
There is also some trace damage which i will have to sort with some wire. My main problem has been identifying the capacitor.
I will attach a pic of the other blown item here. although I think the big blue cap is the main problem.
Thanks for your help guys.
from your first picture, I don/t think the cap is blown
looks like spatter from when the nearby track evaporated!
Good luck with fixing this. I just hope it's a simple trace repair and passive components but be prepared to replace a lot more bits.
Is the board mains powered? If the cap is splattered with metal then you'll have to
replace it anyway as its a future short-circuit risk.
If something has failed dramatically like this its best to be able to test with a
current limited supply after fixing, in case the root cause is still there and it
just pops again.
For DC a lab supply gives you this - for mains equipment its harder, perhaps rigging up
a tungsten bulb or two is series (but safely, of course), but not all mains
supplies will tolerate under voltage anyway. Test as much of the circuit as you
can with a multimeter looking for shorts and damaged components.
Thanks guys, the small cap is definitely blown. thats said thanks for your input on the larger one.
I am getting a reading off my multimeter across the cap posts which means it still seems to be conducting. im not sure if I should expect a blown cap to conduct.
If it is just trace damage and the small cap then I may get lucky and repair all the traces and the small passive bits.
Can the residue be cleaned off the potentially unblown blue cap to prevent shorting?
