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Help! Identifying tiny SMD transistors.

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HarveyH42

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I've got a solar light that stopped working. Pretty simple circuit, diode for charging the batteries, 2 transistors and a few resistors to switch on at night, solar panel is used as the light detector. I've never messed with SMD, so no idea where to look, or how to decipher the markings. I plan to replace with through-hole, little higher power transistors, since I believe the failure was do to running a string of battery powered LED Christmas lights.
both.jpg
(click to enlarge)
Hope the photo is clear enough, took a few try to get one this good, don't think I can get much better. They are really small parts, but believe there is enough copper to solder normal transistors to, maybe even drill holes...
 
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Three terminals does not mean it's a transistor.. There are a lot of different components they could be. Diodes, SCR's, regulator, hall sensors, any number of a dozen other things.
 
They are SOT-23 devices, and like Sceadwian says they could be a lot of things. Probably transistors, but not necessarily.

If you can look at the board and figure out how they're connected (like a small schematic section with the unknown 3-terminal device at the center) then it might be very helpful in figuring out what they are.
 
Some additional fuzzy pictures... These are pretty much the whole 1.5 inch x 0.5 inch board. Only a through hole diode on the reverse.
board3.jpg board.jpg board2.jpg
 
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They are really small parts, but believe there is enough copper to solder normal transistors to, maybe even drill holes...

Lower transistor: as Diver300 said.

Upper transistor: should you need to replace that one too, it is a BC817-40.
 
So both are NPN, general purpose transistors? Think I could replace both with 2N3904 (mostly have a bunch). My load shouldn't exceed 160 mA. Would like a little more of a margin, but should get it working again. Plenty of room in the case for a new board, if needed. Thanks, will give it a try a little later.
 
eng1 how did you determine BC817 and 3904?

According to the markings on the case, W1A denotes the PMBT3904. More precisely, *1A = PMBT3904 (IIRC the first letter specifies the country where the transistor was manufactured). 6C denotes the BC817-40 type.
 
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**broken link removed** to a web page which lists about 10,000 SMD marking codes...

Jeff
 
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