SMD CODE

https://www.taobao.com/list/item/565934482227.htm

https://www.google.com/search?q=transistor+vs+bjt&oq=transistor+or+bjt&aqs=chrome.1.69i57j0i13j0i13i30j0i22i30l7.10268j0j7&sourceid=chrome&ie=UTF-8

Try a tester...

Here is something you can try: Get an ohmmeter and measure between pairs of leads on the chip. If reversing the red and black probes results in a the same reading, the device is probably not a bipolar junction transistor (BJT).

SMD transistor 69W WP9Y 23AL 52AP1 AHPB 72ABE SK S8C6A N21U L8C6A

...from link in #1

L8 in this SMD reference is for schottky barrier (double) diodes...

Here is a link you may find helpful.

https://www.sphere.bc.ca/download/smd-codebook.pdf

I was not able to find your numbers,but it may be useful in the future.The codes are constantly changing,and some are proprietary.

What type of a board are these used on?Manufacturer name?

Some companies I have dealt with erase all ID numbers from their chips to prevent knock offs.

They require off-board testing which is difficult with SMD's especially the really small ones,and a good component may be damaged during removal.

I see that the two devices are in the same position on two different PCBs. So it's reasonable to assume that they are essentially the same.

Also the two bottom legs connect across a large (polarised) capacitor, so a voltage regulator as per Rixter's post #4 makes sense.

I don't have a use for this and I still want one!

I used to build circuits back in the DIP days when I could breadboard them and then wire wrap once I got what I wanted. I can't even see SMDs, much less solder them...

Now for those shaky hands....

https://newatlas.com/high-tech-handrest/14444/

A quick note about the beginning of that first Youtube where he recommends some very sharp test probes.

I have always found that In circuit test fixture pogo probes are the best

Although they don't look very sharp here

The tips are actually shaped into four separate points

Incidentally the meter itself was bought before my last job which I was in for over thirty years, I've been retired for over three years now, and, the meter was the cheapest "shirt pocket" one I could find at the time. It uses a tiny voltages to measure resistance so that no PN junctions get forward biased when probing in circuit, so it has always been my go to meter for such tasks.

For very small soldering I made my own tips.I used copper wire of various gauges depending on the application.I once replace a SIM on a digital watch with a red LED display,Timex I believe if memory serves me right. The factory said I did not want to do it,but I insisted,and they sent me the chip,free of charge and wished me good luck. I used a 10X magnifying glass,and a not so small amount of Scotch. It was very tedious to say the least,and I would not try it again,especially now since my hands are not very steady,and my eyes are not that good. (The Scotch is still good though). The hardest part was preventing bridging of the pins.Used a lot of solder wick,and a quite a few 4 letter words. This was back around 1980,and I am sure they are even smaller now. For testing I use safety pins or straight pins. A safety pin can be inserted through the insulation of wires,and will stay put,or can be securely attached to a ground connection. I have an Old Fluke that has a diode test and resistance test,and conductance (nS) test.It is over 30 years old and still works fine,even though the display screen has it's share of age spots,just like me.

See a new thread I've posted. Note that at the end of the post I've said that when you can see clearly your hands seem to stop shaking nearly so much.

I looked in The SMD Codebook:

The L8 device on the right may be a dual diode:

L8 BAT721A Phillips SOT23 dual common anode 40V 200mA Schottky

L8 BAR15-1 Siemens - dual PIN 100mA max

The 8B device on the left could be one of these Motorola (ON Semiconductor) parts:

8B MMBZ5227B Mot C SOT23 3.6V zener 0.225W

8B MUN2212 Mot N SOT23 npn dtr 22k+22k

8B MUN5212 Mot N SOT323 npn dtr 22k+22k

The last two devices are "digital transistors" with a 22K resistor in series with the base and another in parallel with the base-emitter junction. The SMD Codebook also lists a voltage regulator, but it's in a SOT89 case, so that one is not what we're looking at here.

Have you contacted the device manufacturer for documentation? I admit schematics and parts lists are a rarity outside of the authorized fabrication chain but one should still look for one.

Most electronics these days are not designed to be repaired primarily because of component failures cascading the electrical disaster to other areas. Also, just the cost of troubleshooting down to the component level often exceeds the price of a whole new device.

The way they are connected tells me it is typical of a regulator with a protection diode or part of the switching of a buck converter circuit.