Help me identify surface mount capacitor or resistor (Urgent) - Page 1
Forum section: electronics / repair

author: DIYmaster
author_rank: Newbie
timestamp: December 08, 2014, 10:43:58 pm
content: Hi guys I'm messing here with some electronics and soldering, but I made a little mistake and I'd like to fix it as soon as possible. My soldering iron accidentally must have picked one of the brown resistors? capacitor? and now I lost some functions. I tried to take it off the soldering iron immediately but it was so small it was difficult to act fast and now it became a little bit black. I would like to order whatever that thing is called so i can replace it with new one. Can you tell me what it is and the correct spec? Trying to google or ebay the stuff turned out to be a nightmare as none of it is recognized by color but then again I don't see any numbers either.Here is imageSo we have light brown and dark brown option. Note how the dark brown is lower profile. I checked around what I have from spare computer parts and the light brown high profile stuff I have plenty. But I don't have anything in the dark brown variation. Maybe I can test solder one of the light brown in there and see if it makes a difference? Many thanks people!

author: KJDS
author_rank: Super Contributor
timestamp: December 08, 2014, 10:48:08 pm
content: It's a capacitor. You can probably get away with soldering what you have in there and trying it, but finding a schematic and getting the value would be my first step, then measuring the voltage across the pads to see what rating you require would be the next.

author: DIYmaster
author_rank: Newbie
timestamp: December 09, 2014, 06:46:41 pm
content: KJDS great advice, I got one of the taller light brown capacitors soldered on and it actually made some difference but it seems to be the wrong type. The functions the board performs were not correct but still better than totally dead. This is good news as now I know the fault is exactly that capacitor. I wish there was some markings to tell me what it is. It's gonna be such a pain finding what I need to buy.

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 09, 2014, 07:08:26 pm
content: That looks like a common bypass capacitor on a digital circuit.It is difficult to understand how removing one of those would actually change the function of something.What exactly is this gear we are looking at? Context here is very helpful.

author: TMM
author_rank: Frequent Contributor
timestamp: December 10, 2014, 06:48:53 am
content: Computer graphics card?Looks like its an 0805 size surface mount ceramic capacitor. I would hazard a guess at it being 100nF but the value really could be anything.A cap that looks similar on a different board isn't guaranteed to be the same value - you can get a variety of values in the same physical package. Your best bet is probably to measure the capacitance of another cap on the same board which looks identical to the one that came off. Hopefully the designer has used only a handful of values and the ones that visually look the same have the same value. There is no guarantee of that being the case however. Even better would be to find another working board and measure the capacitor in that exact position.You might need to desolder the cap to measure it's capacitance accurately. The capacitors are likely in parallel with many other caps, so the measured capacitance will be far higher when you try to measure it in circuit than if you desolder it and measure it out of circuit.You can bodge on a leaded capacitor if you don't have any surface mount caps, just be very careful because the pads are likely to lift easily having a big leaded capacitor hanging off them. If you can get it working with a leaded cap then just add some epoxy or hot glue to make the repair mechanically robust.

author: DIYmaster
author_rank: Newbie
timestamp: December 18, 2014, 04:30:12 pm
content: Hey guys thanks a lot for your help. I just wanted to say that I fixed it now. Nobody seems to sell surface mount capacitors like this, so I found some from another scrap board and as soon as I replaced to dark brown capacitor, everything started working as it should. Next time I should be more careful when I solder so close around the chip.Also here is another fun thing:

author: rob77
author_rank: Super Contributor
timestamp: December 18, 2014, 04:45:53 pm
content: just for the sake of curiosity...how could someone accidentally pick up a 0805 capacitor with the soldering iron ?of course it happened to me that i "kicked" off by accident some 0402 parts with tweezers while replacing a QFN chip with hot air (i was lazy to secure the parts around the chip with kapton tape and then spent 20 minutes with a big magnifying glass to solder those little bastards back)... but remove a 0805 by accident ?, even 0603 is big enough to be safe