Help with part identification? - Page 1
Forum section: electronics / general

author: Mochaboy
author_rank: Contributor
timestamp: June 05, 2013, 03:29:00 pm
content: Hello folks!Long time lurker, first time poster. I come from the RC world but recently discovered electronics through the gateway drug known as arduino (don't hate on the 8bit'rs)...Anyway - I flywith autonomous flight controllers and video transmission equipment (FPV in rc speak)...One of my fellow flyers handed me a burned out circuit board. The pads were mislabeled, polarities were switched and the fun that is magic white smoke ensued (along with a lot of cursing - this isn't a cheap board).I'm having trouble identifying a burned out component (see attached image)...Best I can make isEM89ABS00001BThis is what the product is:http://team-blacksheep.com/products/product:14http://team-blacksheep.com/tbs-core-manual.pdfWhat this is a power distribution circuit board with an optional onscreen display overlay onto the video feed. As a side note, this is handled at least on the arduino side with an atmega328p hooked into a Max7456 video driver, but on this board I see a PIC and then burned out component that I can't identify.Quick searches turned up parts suppliers in HK to a S0001B in a QFN-14 package, but there's no mention of who the manufacturer is or what this part does. I've reached out to the vendor for this board and haven't received any responses, and this may turn out to be a dead end, but I thought I'd reach out to the experts before I threw in the towel.Any ideas, or suggestions on how to continue my investigation? I'm always looking for a reason to buy new toolsFYI - image - a chipped capacitor is also highlighted - I just bought a capacitance meter to match that part...

author: senso
author_rank: Frequent Contributor
timestamp: June 05, 2013, 08:50:26 pm
content: That seems to be a National Semiconductor(now TI) switching regulator.

author: juani_c
author_rank: Contributor
timestamp: June 05, 2013, 10:25:17 pm
content: It seems to be aLM2700 600kHz/1.25MHz, 2.5A, Step-up PWM DC/DC Converter

author: Mochaboy
author_rank: Contributor
timestamp: June 06, 2013, 02:15:20 pm
content: I'll go ahead and remove the part to count up the pads below...QFN packageswitching regulatorthe mystery continues

author: juani_c
author_rank: Contributor
timestamp: June 06, 2013, 03:02:31 pm
content: Quote from: Mochaboy on June 06, 2013, 02:15:20 pmThe LM2700 is a National Semiconductors part, same as your part logo.The LM2700 is a DC/DC Converter, your part seems to be a switching regulator.The LM2700 comes in a WSON package, that's pretty much the same as your QFN part.The LM2700 in WSON packages has the code S00001B as the Top Side Markings (page 20) .

author: Mochaboy
author_rank: Contributor
timestamp: June 06, 2013, 04:26:58 pm
content: Juan,You're going to have to share with me how you narrowed it down to that part. It will save me stumbling around blindly in the futureI'm laughing because I stopped at around page 15 on the datasheet, if I'd just read a few more pages I would have noticed the top side markings table.I really appreciate you zeroing in on that.I'll go ahead and put the digikey order in today...my capacitance meter came in today so I'll get started with matching up the capacitors as well.I'll update with my progress when the replacement parts come in!!!

author: Mochaboy
author_rank: Contributor
timestamp: June 06, 2013, 04:29:01 pm
content: ps - removed part attachedThat's going to be challenging to rework - I may just remove all the surrounding components to make my life a little easier.

author: juani_c
author_rank: Contributor
timestamp: June 06, 2013, 04:45:12 pm
content: i can't remember exactly what i searched for in google, I think it was something like;NATIONAL SEMICONDUCTORS switching regulator + "S00001B"and inhttp://www.datasheetarchive.com/I found that part name.PS: I made a blog post a while back explaining how I search for SMD parts codes;http://ssihla.wordpress.com/2013/03/04/recycling-electronics-component/

author: Hardcorefs
author_rank: Regular Contributor
timestamp: June 07, 2013, 10:15:50 am
content: Watch out!!!!Check the FET that it drives and also the diode just above it and to the right of your picture (A7) also the inductor.Just replacing the part might not work.....

author: Mochaboy
author_rank: Contributor
timestamp: June 07, 2013, 01:42:05 pm
content: Is there an easy way to verify if the FETs and Diodes are functional? I'd imagine a 1 way continuity test for the diode, but what about the FET?

author: Anks
author_rank: Frequent Contributor
timestamp: June 08, 2013, 09:26:47 am
content: check the FET for shorts with your DMM.

author: MacAttak
author_rank: Unknown
timestamp: June 08, 2013, 05:25:47 pm
content: My understanding was that a chipped cap or resistor couldn't be reliably measured - the physical damage alters the electrical properties of the part.My understanding could be wrong though

author: Mochaboy
author_rank: Contributor
timestamp: June 11, 2013, 03:14:41 pm
content: Quote from: juani_c on June 06, 2013, 03:02:31 pmThis should be no surprise, but the vendor confirmed Juan's postYou win a silver!Parts are ordered, along with a hot air rework station...Love how this little board turned into a $150 purchase, like I said, I'm always looking for a reason to buy new toolsI picked this uphttp://www.amazon.com/853D-Rework-Soldering-Station-Solder/dp/B009PP36MKFor the simple reason it has an integrated adjustable bench power supply, 15v up to 1amp...more than enough for my basic needs for now. If I need more amperage down the line, I'll get a proper bench power supply

author: Mochaboy
author_rank: Contributor
timestamp: June 18, 2013, 08:02:56 pm
content: Juani_cIt workedI replaced the 2 capacitors as well just to be safe and everything fired up. 5v input getting me 4.75v outputs on the 2 output rails, so I'm guessing this surgery was a success

author: juani_c
author_rank: Contributor
timestamp: June 18, 2013, 08:09:25 pm
content: glad to hear that!ps: the soldering looks good