I need to identify this burnt chip so I can order one to fix this motherboard. I have bought a replacement motherboard and have tested the chip on it. So far I’ve had no luck on other forums. I have a few ideas of what to buy to replace the chip, but not sure I want to just guess. The markings from what I can tell are “3D” and “U5”. I attached a pic of the burnt chip next to Q2501 and another pic of the bad chip with a BC856 transistor next to it. The Bc856 is 3.0mm x 1.4mm, so the bad chip looks to be somewhere around 2.0-2.2mm x 1.2-1.4mm or close to this. Then a pic of my new motherboard, with the good chip. Any help would be appreciated.
I tested the good chip on my new mother board and only got 2 readings other than OL trying every combination of leads to legs. The 2 readings were both 0.264v and they were both with the black lead on the leg that’s by itself, then touching either of the 2 other legs. Does this mean it could be something other than a reansistor or just that the chip needs to be removed to test? The board has had no power applied to it for several days.
The part marking of “3D” and the package seem to come back to either an NPN transistor MMBTA44 or a PNP Transistor BC856. Let me do some digging and see if I can verify one or the other basked on the pictures.
The chip in the pic next to the burnt one is a BC856 and a MMBTA44 is the same size, which is about 3.0mm x 1.4mm. This means that this chip is about twice as long as it’s width. The burnt chip has a length less than 2 times it’s width or about 2.0-2.2mm x 1.2-1.4mm. And thanks btw for your help, much appreciated!
Marking lists 3D
No verification, however a possibility.
Thanks Robert_Fay, I also found that one, but haven’t gotten any replies on other forums as to if they thought it might work. What would you do if you were in my shoes? I have the computer working, so it’s not a problem. I just have this extra motherboard with the bad chip that’s worth somewhere around $200 when working…lol. So I think it’s worth a try to order some chips and see what happens.
You are in a tough spot. Without a manufacturer willing to share a component list you may never be able to verify 100%, second there is a chance that something else failed on the board and this just happened to be the weak link that burnt up, so even a new IC may not fix it.
Personal opinion and no guarantees here, is that if no one comes up with a confirmed answer I would spend the $1 and give it a try. Worst case you are out a dollar. Best case you have a good spare.
I did finally talk to the person who had the laptop and he said he hooked up the battery and heard a very faint “pop” and it has never worked since. I thought it was strange getting those 0.264 readings from the good chip, but I don’t know enough to know anything…lol. I just don’t want to chance taking the good chip off the good motherboard. I’d probably mess up and have to buy another one.
Check this out. Looks like there are many to choose from. Very confusing to an amateur like me…lol. But I guess there are only 2 with the 3D% marking. What is the “%” after the 3D? Ugh!! https://www.nexperia.com/products/bipolar-transistors/general-purpose-bipolar-transistors/transistors-single-pnp/series/BC856W-BC857W-BC858W.html
Based on the marking there is only 2 and really they are the same part, just different manufacturer packaging size. - Robert
I’m ordering 2 of them now. They are so small, I’m afraid I’ll lose one…so maybe I should order several…thanks again for your help! Oh, btw, do you do any chip-level soldering?
Glad to help.
Personally I don’t do a lot of SMT chip soldering, however there is a number of techs here that do.
Ordered 4 BC856W’s and as I was checking out, I experienced something that blew my mind! I am constantly ordering parts and other things and in 30+ years of doing so, I have never seen this…
Do you have a web id number for you order? Not sure this is correct.
I have this… Mouser Purchase Order Number : NX1090 and Invoice Number : 54970004 I downloaded the invoice as a PDF, but it says I can’t upload attachments, because I’m a new member. I got a message from UPS saying the package will be delivered tomorrow by 10:30 AM…pretty incredible! I ordered from Nexperia, but it says Mouser on the invoice. Also, it’s coming from Mansfield, Tx, which is only about 3 1/2 hrs away.
Nexperia, and AFAIK all other semiconductor manufacturers, do not handle orders of less than 1000 pcs in house. Some won’t touch less than 100,000 or 1,000,000.
That’s Mouser’s location and being so close to you is probably why there was no extra charge for next day delivery from Mouser.
Considering you got help from a Digi-Key employee, it would have been nicer to order the parts from Digi-Key rather than their competitor.
I had no idea about them being a competitor. I really don’t know much about electronics or circuits, which is why I’m here trying to learn and get help finding a chip. If the chips I ordered don’t work, I’ll be sure to order from DigiKey. Although such a small order might be a hassle, no? If you don’t think so, I’ll gladly order from here. I apologize to anyone I offended and thanks for bringing this to my attention.
I’m sure no one is offended, mistakes happen.
Digi-Key definitely caters to all buyers from those who want a few parts where shipping price is higher than the parts price, right on up to large commercial volume buyers. Check out the link for this part up in post #5 to see the excellent Digi-Key parts page with tons of info and fixed rate pricing from 1 to 1000 pcs.
Will do and thanks again. The way I see it, these little chips can make a great laptop out of a paperweight. So even if they were $50/each it would be worth it to me. I’d rather buy from a company that has people like you and Robert_Fay available for some help, than one that might be a little cheaper, with no help. Without y’alls advice, I might never get this fixed.
Just to be clear I’m not a Digi-Key employee, I’m just a very satisfied customer who likes to help others on the forum.