Want to check my info on SMD part  - Page 1
Forum section: electronics / beginners

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 28, 2016, 04:19:27 am
content: I am working on a high quality inverter and found some issues , one is that it seems high current or something has blown on component off board and another almost these are SMD 3 leg , they appear to control LEDs the markings are 702 4I think I found a manufactures info that may match - LT 3965 8-witch matrix LED dimmer ?I used my iPhone and the site is telling my the file is too large ?

author: DivineChaos
author_rank: Regular Contributor
timestamp: January 28, 2016, 05:00:03 am
content: I wonder if it blew itself off the board. Crazy. As far as picture size goes, it can't be more than 1000kb.As far as the component goes... I'll edit my post when I find it

author: dadler
author_rank: Unknown
timestamp: January 28, 2016, 05:14:41 am
content: Likely a SOT-23 2N7002 n channel mosfet.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: January 28, 2016, 06:45:09 am
content: Quote from: dadler on January 28, 2016, 05:14:41 amI concur. Many manufacturers use the "702" designation for the 2n7002. The "4" is probably a date code.QuoteWhaaat? The LT3965 is a 28-pin TSSOP package.......

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 28, 2016, 03:36:27 pm
content: With more magnification than I can get with the phone camera , I can see that what looks like cold solder joints on 2 of the 3 legs of the one that is crocked , I think that they took them selfs off the board - I think the inverter was connected to the battery bank with reverse polarity ? this board is the control board .On the other board that has the large battery connectors , one of the diodes was shorted , again with wiring diagram / schematic and not being a engineer to be able to reverse it, I just figure its part of the protection circuit , right next to the fuse & other beginnings of the input .As far as using the LT 3965 , that is what match the Google search & picture on the data sheet , again being kinda new , finding sources of info & stock , I find it difficult , I get lost looking at sites like Digikey , etc.I did not like the high prices at radio shack & limited components , but is was easier to do repair when I could just go match the part .We have lost lots of sources , several good surplus places have closed and some of my friends that had shops retired - doogie dew .Thanks John

author: dadler
author_rank: Unknown
timestamp: January 28, 2016, 09:21:31 pm
content: Did you post the wrong picture?In the posted picture, the small components are certainly not LT3965s.Based upon the marking and layout they are likely mosfets, as above.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: January 28, 2016, 10:55:11 pm
content: Maybe the LT3965 is out of the posted picture frame. But the Data Sheet for the LT3965 does not indicate the use of extra mosfets on the LED driver outputs, it is designed to drive the LEDs directly. I don't see any mosfets in the application circuit schematics in that function.Certainly... if there is a LT3965 on that board, I think replacing it will probably be out of the question. This is a major rework issue, and it will be far more difficult than replacing the 2n7002 mosfets.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 29, 2016, 01:54:48 am
content: Everythng is a repeat , the picture is correct , there were 4 of them , the 3rd is crooked , the 4th is missing - jumped off the board .As for the part number LT3965 again a repeat , the goole search got me to a spec . / data sheet that may have been the wrong picture , but it showed what I pictured , can't tell ya why the difference , just repeat what happened .Stopped by a local surplus place and found some of the through parts but non of the SMD , they just bought out another surplus place and most of the SMD parts are still on pallets in the warehouse , so my have to go to Digikey , Mouser etc.Once the inverter is repaired , need to get new batteries , the old ones were Trojan L16 x 4 , when I get new batteries , I would like to buy nickel-iron batteries for the cost , longevity , performance .

author: DivineChaos
author_rank: Regular Contributor
timestamp: January 29, 2016, 11:58:15 pm
content: Found

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 30, 2016, 02:50:30 am
content: Looks like a phone app , thanks .

author: DivineChaos
author_rank: Regular Contributor
timestamp: January 31, 2016, 09:38:40 pm
content: It's called "smd code"

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: February 01, 2016, 07:53:45 pm
content: Now this is where I get lost , pages of options , no wiring diagram / schematic from manufacture .they are lighting LED's ?http://www.digikey.com/product-search/en/discrete-semiconductor-products/fets-single/1376381?k=2n7002