Transistor or V regulator identification - help

[valentino_val]

Hi, need help with identification one transistor (or maybe voltage regulator). I need to replace it.

MMBT2907A ???

The transistor is burned and is from car's gas analyzer machine that have problem with the display.

[eccerr0r]

Re: Transistor or V regulator identification - help

MMBT2907A is reasonable for that position...

[PeteS in CA]

Re: Transistor or V regulator identification - help

An MMBT2907A is a surface-mount version of the venerable 2N2907A, a PNP bipolar junction transistor. The 2N2907A and NPN 2N2222A have probably been working in electronics longer than I have.

[eccerr0r]

Re: Transistor or V regulator identification - help

Actually know what, on second thought there is some problems with a 2n2907a there... hmm... tricky...

Main reason why: because this thing will get hot among other stuff ... perhaps this is why it blew in the first place, then again other stuff could also blow..

Hate second guessing the original designer, though even if a regulator IC is here, it still would get just as hot. This is a really weird thing that's being done here.

[budm]

Re: Transistor or V regulator identification - help

The schematic drawing does not match the board layout, for example: the resistor 8061 is directly connected between Base and the Collector pin of the Transistor, but the drawing shows it has Thermistor connected to the Base first then to the 8061 resistor.
Did you use diode mode to test the junctions of this Transistor?

[valentino_val]

Re: Transistor or V regulator identification - help

The schematic drawing does not match the board layout, for example: the resistor 8061 is directly connected between Base and the Collector pin of the Transistor, but the drawing shows it has Thermistor connected to the Base first then to the 8061 resistor.
Did you use diode mode to test the junctions of this Transistor?

Thanks for the answers, but the schematic drawing is ok (attached the new foto of the resistor 8061 connection). The transistor is burned (have fuga) and test the junctions of this transistor is not correct.