SMD Identification and parts cross - Page 1
Forum section: electronics / beginners

author: PMA2025
author_rank: Newbie
timestamp: April 24, 2025, 10:40:00 am
content: Hello Everyone.I'm new to electronics and have trouble locating data sheets and cross-referencing replacement parts for two components: a voltage reg and an IC. See pics. I know the IC is a National Semi, which is now Texas Instruments. I did find an LM1117IDT-3.3 TO-252, but I'm not sure. The volts reg I got nothing.In case the attached pics don't attach, here are the numbersIC-- 51A82E LM1117 IDT- 3.3VR-- 3278 N06BAny helpful resources would be great. I'm willing to put in the effort, but it seems like I'm having the same luck if I look for these in my garage.Thanks You!

author: little.tesla
author_rank: Regular Contributor
timestamp: April 24, 2025, 10:54:20 am
content: Hi,It's this one:(VR2 suggesting "voltage regulator")N06B --> LM1117IMPX-5.0Datasheet (Page 24)

author: PMA2025
author_rank: Newbie
timestamp: April 24, 2025, 11:42:44 am
content: Thank You. Yes, the VR2 is a regulator. I'm working on reverse engineering to see how it's wired in the circuit, which will help me find a replacement part. Just because these numbers don't make sense to me doesn't mean someone with experience couldn't know more.I will check that data sheet. Thanks. Would LM1117 IDT-3.3 be enough to cross-reference? Is 51A82E like a manufacturer s/n?

author: little.tesla
author_rank: Regular Contributor
timestamp: April 24, 2025, 12:25:38 pm
content: In the same above linked datasheet you will find on page 23 the IDT- 3.3 variant which is in TO-220 package, for this specific case the MPN (Manufacturer Part Number) is sufficient to identify the component. Sometimes it might be of advantage to explicitly state what is the package / fixed voltage.Regarding S/N of components. A S/N is not common, even not in high-rel applications for more standard components. Usually you will find a coded DC (Date Code) on the component.As an example first line:AYW (or a variant of it)A = Assembly LocationY = YearW = Work WeekSecond line:Specific Device CodeMarkings are usually specific for a certain manufacturer or a component family, I'm not aware of a standard. In some datasheets you will find details on how the component is marked and their meaning. Be aware that many component manufacturers offer to perform customer specific markings or even to remove the markings (I'm not talking about grinding markings away). Sometimes the same marking is used by two different manufacturers on totally different components, in such cases the package can help to narrow down the right component.For crypto devices the markings can be random for obfuscation.

author: PMA2025
author_rank: Newbie
timestamp: April 24, 2025, 12:38:13 pm
content: Thanks for the help. I'm finding electronics repair has four skill sets to develop. The first three I'm learning. 1) Component identification, function, testing, and troubleshooting. 2) Component removal and installation, soldering. 3) Component research datasheets/cross-reference. 4) PCB design.Thanks again for your help.

author: Fflint
author_rank: Frequent Contributor
timestamp: April 24, 2025, 01:00:34 pm
content: Identifying small smd components is a serious hassle. Why can't they just print the bloody part number like they used to? The size is not an excuse. Many absolutely tiny parts have 6 or 7 digit markings visible under a microscope. But it would mean a fraction of a penny higher cost to laser on these markings while no one cares about repairability. Surely not an RF transistor maker like Mitsubishi that puts Y5 or Y1 as their marking .Anyway. I found one unexpected method of identifying such (especially older) parts is if you know roughly what the part is. Like a voltage regulator, or an rf transistor. You can go to Aliexpress and search for "rf transistor Y5" and you will find some guy that sells it and often he will have the actual part number in the title.This is how I managed to fix few items that would've 100% hopeless to fix. Also many of such parts are "deprecated" and you can't even buy them anywhere else than on Aliexpress .There are also some parts you can't buy anywhere. This includes one voltage regulator that shows up on these 3.3 and 5V dc buck/boost converter. I once had one of those to replace and I had to buy the entire board (that cost something like 50 cents) to get it.

author: PMA2025
author_rank: Newbie
timestamp: April 24, 2025, 01:22:40 pm
content: I now see the value in collecting old boards. The way the world is changing, the ability to repair these circuit boards is a superpower skill set.