Milwaukee M12-18C Charger: Identifying AZ431 Voltage Regulator, Q3 Transistor & Purchase Options

Hello experts,
On the table, the Li-ion battery charger with the title.
1. The AZ431 precision voltage regulator in the TO-92 housing is definitely damaged (full short circuit between REF and Anode) - Where can I buy one?
2. And the second transistor described on the PCB as Q3. You can barely see such a description:
RBA
1AM
(ON production)
Kind of simple identification because it comes out that it is a regular 1AM but the housing does not match - in my case it is SOT-89 and where I am not looking for it, 1AM is in a smaller SOT-23 housing .... Does this mean that HE coded this element and it is not 1AM? It does not have a complete short circuit but the transition in all possible directions and on all terminals - hence the conclusion that it is damaged.
Will anyone be able to suggest something?

AZ431 does TL431 not fit?

Thanks, you're right. So the topic TL431 sorted out.

What about the 1AM transistor?

http://www.s-manuals.com/smd/1a ale w SOT-23.

Dear Colleagues,
After a few days of hard tests, studying the application of the TL431 chip, I still can't get over it.
Please take a look at the picture - I described there the leads and a fragment of the circuit with this unfortunate missing transistor that I can't choose.
The original AZ431 had the REF pins rotated and the cathode relative to the TL431 counterpart. This, of course, I have improved, but I still can't find the missing transistor.
I do not expect a ready solution but only hints because their types (BC639 and two BC639 combined in a Darlington system) did not work.
I look forward to discussion.


Added after 6 [hours] 26 [minutes]:

Missing transistor topic resolved:
well, the manufacturer in the SOT-223 enclosure also produces 1AM transistors under the name PZT3904. That's a lot. For lack of such I substituted 2SC945 (the basic parameters were similar to the original) - but I am not entirely sure if this is a good choice.
No less the charger started, but the symptom with which I received it still remained: even without a load, after a while, the voltage on the secondary side of the transformer dies - the one that I marked on the photo. i.e. 22V. The second voltage is present and amounts to 19V (interestingly, it is also normally 22-23V, it drops to 19V when the first voltage is missing). Without thinking, I substituted TOP255EN converters for a long time, but nothing changed. I checked all capacities, diodes and even replaced 817 optocouplers and nothing else.
Hard case.

Micek64 wrote:

The second voltage is present and is 19V (interestingly it is also normally 22-23V, it drops to 19V when the first voltage is missing)

Hello.
Could you mark the other tension? From the attached photo it can be concluded that on the secondary side of the transformer there is one winding is 22V. Check the resistor R25 4.7k? (somehow it looks suspicious in this photo).
Greetings.

PS
It would be good for you to include a full photo of the PCB.

Hi,
The 4.7k resistor is OK.
Late in the afternoon I will post a full photo of the PCB with descriptions.
Yesterday I tried U3 - LM358 in the picture and still without effect.

Added after 4 [hours] 27 [minutes]:

Another thing I already know is that choosing C945 instead of 3904 is a bad idea. C945 is not suitable for fast switching applications. I will exchange it for BC639.

Added after 7 [hours] 20 [minutes]:

I add a whole picture.
I applied the value of the second voltage there (which drops to 19V when the first one is missing).
I also replaced 2SC945 with BC639 (TO-92 in SMD version) ) but nothing.


However, I noticed one thing. When the device is turned on, the voltage that dies is 22-23V. And after a few minutes it gradually decreases (nothing warms up, the charger is not charged with a battery) and so up to 0.5V
Maybe I bought a fake of this TOP256. It was quite cheap on Farnell but I didn't find another one anywhere.

Added after 16 [hours]:

Zero ideas?

The charger took off after stubborn efforts.
1. The blame for the lack of one of the voltages was a 51? resistor plugged in with 4M? between the + 340V power supply and the V (Voltage Monitor) pin of the TOP circuit. The resistor was conducting when he wanted to be away whenever he measured it.
2. after removing the abovementioned fault, the UPS still showed no signs of life. Therefore, once again (already the nth) I looked at the TL431 system and its surroundings. And unfortunately at the beginning I made an unforgivable mistake here - I wrote that the original AZ431 has K versus TL431 turned from REF. Well, complete nonsense . AZ431 had a pin description from the top (about which the manufacturer loyally informed under the description and which description I did not read) and TL from the bottom - hence the misunderstanding.

3. The charger has started after removing this sell.

Thank you very much!