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Hi, I need to fix my led aquarium lights that has a damaged sot23 transistor but need help in determining the correct part to order. As per the pic their is a marking of B28W and the transistor sits right next to a 0 ohm resistor and a cap.
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Hi John,
Man, talk about going down the rabbit hole on this one! I wandered some pretty far flung corners of the internet poking around looking for SMD marking codes.
A big problem here is that apparently a lot of manufacturers only use like one or two letters for a part identification, and the rest may well be year, work week and/or lot code.
The most promising lead I found was a PDF for something called Micro3 (company name, maybe?) that gave their package markings. Under the SOT-23 page, a table indicated specific part numbers associated with only the first digit, "B", saying the part number for that is IRLML2803.
01-0041 Version 37, MARKING PACKAGES Model (1)
As you can see in the image, the next two digits are year and week, which would say that the second part, B2Y7 was made in 2002 or 2012 (and depending on how out of date that PDF is, possibly 2022) in work week 25 with a Lot Code of 7. This would indicate that the two parts are actually the same; they just have different manufacturing dates, which would make a certain amount of sense. Unfortunately, the decoding breaks down on the first part, the damaged one, since the work week code on that one is an 8, and according to that PDF file it should be alphabetic (A-Z), so I have no idea what that means; possibly that I've chased that rabbit into a maze and lost it completely, lol.
Anyway, a search for IRLML2803 came up with a part identified as MOSFET MOSFT 30V 1.2A 250mOhm 3.3nC LogLvl on mouser.com, which would make sense for that part, but who knows?
IRLML2803TRPBF Infineon Technologies
That's all I got for ya; dunno if it's going to be a help or just a distraction, but there you go.
Good luck; let us know how it goes!
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@dadibrokeit The code B2Y7. that led was made in 2016 and the one stamped B28W that was made in 2019 as the boards have stickers with the year code on it and it also goes inline with when these lights were released on the market. Thanks for looking up the info. This is going to be a tough one.
@ntec I did a bit more poking around; didn't find information for you, but I did run across a thread on an aquarium forum where the guy talked about basically rebuilding an entire circuit board; not the same model as yours, but it was the same brand. I'm thinking you might be able to find out from him what that U1 part is. Here's the website.
@ntec @dadibrokeit since we have two components with the identical 2 letters in the beginning, it stands to reason that B2 is the part number. The following alphanumerics could just be production, date or other not quite relevant data.
RT9169-13CX is a B2 marked SOT-23 part and is a voltage regulator. @ntec, here is the datasheet RT9169 Now use your multimeter and measure pin 1-3 and compare your values against the data sheet. If it is not a regulator you will not get those values :-)
@dadibrokeit I actually emailed that guy couple days ago as he fixes these lights. He actually does not know what part it is either and just grabs the part off donor boards but thanks for looking.
@ntec, any chance you have access to an oscilloscope? It would be really interesting to see what signals are going into that chip. If it's a MOSFET, we might see PWM square waves going in and out, with the source and drain following a lower-voltage gate signal, or if it's a single-line EEPROM then you'll see power and ground with data going over the other line. Given the dynamics of LED operation, I don't think a multimeter will give you enough information.
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Hi John,
Sorry to start another answer, but I wanted to add to what we've been talking about. I found a data sheet for one of the Microchip products that looks interesting.
When I scrolled down the the package marking section, guess what I found?
According to that, the first two characters, B2 designate the part, and the last two are some sort of "Alphanumeric traceability code". B2 corresponds to part number 11AA020 that's referred to on the Mouser site as EEPROM 2K 256X8 1.8V SERIAL EE IND.
11AA020T-I/TT Microchip Technology
So if that's the right part, you should see 1.8V across pins 2 and 3. I'd power up the good board you have and stick a voltmeter on there and see what you get.
EDIT: Actually, according to the data sheet, that part can run with a wide voltage range, anywhere from 1.8-5.5V.
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@dadibrokeit I hooked my meter up and checked pins 1-3 and 2-3 of the working board with lights on and I’m getting 3.2v on both. If it is a microchip eeprom, buying the chip is easy but trying to find a microchip programmer for it is the tough part. Obviously the programmer would have to be cheap enough to make fixing the lights feasible.
I'm not sure if there are other eeprom programmer manufacturers whose product supports the 11AA020 part, but Microchip does make one that's semi-affordable. Their recommended programmer is the PM3, but it goes for like $1100 USD, so probably not what you want to fix an aquarium light.
Here's their "starter kit" for a bit over $100 USD - still pricey for a one time use, but better than the other one.
@dadibrokeit awesome find. Great job. @ntec on your way to getting your light fixed ;-)
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@ntec I wonder if you are looking at a voltage regulator vs a transistor. It would explain its location and being in a light would make sense. It would also make sense that it is label as a "U" for some type of "IC" versus "Q" for a transistor. Have you checked for any voltages on the legs? The center pin should be v+
由 oldturkey03 完成的
@oldturkey03 with the power off I’m getting 0.5v on the leg.
由 John Nguyen 完成的
@ntec any chance you get anything with power on? Does it turn on?
由 oldturkey03 完成的
@oldturkey03 I have not checked with power on but I did notice looking closely there was a burn mark on the chip so I removed the chip. The big issue for me is trying to determine what type of chip this is. I still have my old led boards that still work. The pics attached are the newer version of my old led boards that I am trying to get working. Is there any test I can do with my functioning led boards to try and determine the type of chip it is?
由 John Nguyen 完成的
@oldturkey03 on my functioning board the chip on that board is labelled B2Y7.
[image|2779948]
由 John Nguyen 完成的
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