PNP transistor with diode

Thread Starter

Hamsan

Joined Aug 21, 2021
10
Hello Guys,
I need help find the below PNP transistor used in car ECM. A healthy one reveled following the package is sot89 and marking on it is GA.
IMG_20210821_120656.jpg
 

MrChips

Joined Oct 2, 2009
24,401
Welcome to AAC!

You used a transistor tester to identify a component and this is the result it is showing you?

Try Siemens BAW78A 50V 1A switching diodes.
 

Thread Starter

Hamsan

Joined Aug 21, 2021
10
Welcome to AAC!

You used a transistor tester to identify a component and this is the result it is showing you?

Try Siemens BAW78A 50V 1A switching diodes.
Thanks Mr Chips, I used transistor tester it says PNP transistor but you are saying switching diode, it's new thing for me, how they work?
 

MrChips

Joined Oct 2, 2009
24,401
I would not trust a transistor tester 100%.
Show us sharp close-up photos of the good component and the bad component.
Also show us a clear photo of the whole board.
 

Thread Starter

Hamsan

Joined Aug 21, 2021
10
I have jumperd out AC compressor part with fan since they both work same time almost. T809 part I was talking about
I would not trust a transistor tester 100%.
Show us sharp close-up photos of the good component and the bad component.
Also show us a clear photo of the whole board.
2021-8-21 17-14-50.jpg
 

Thread Starter

Hamsan

Joined Aug 21, 2021
10
I would not trust a transistor tester 100%.
Show us sharp close-up photos of the good component and the bad component.
Also show us a clear photo of the whole board.
The pin two which initially I thought was gate of n channel mosfet is connected to relay of fan. Relay trigger second pole is battery positive. I was sure this was n channel mosfet and replaced one but check engine light came. It is not mosfet I think.
 

MrChips

Joined Oct 2, 2009
24,401
This begs multiple questions.

1) How can you be so sure that it is a PNP transistor?
2) What are the markings on the good component and the bad component?
3) Are you testing the "good" component in-circuit or off the board?
4) What are the voltages on each pin with respect to ground on the good component on the working board?
 

Thread Starter

Hamsan

Joined Aug 21, 2021
10
This begs multiple questions.

1) How can you be so sure that it is a PNP transistor?
2) What are the markings on the good component and the bad component?
3) Are you testing the "good" component in-circuit or off the board?
4) What are the voltages on each pin with respect to ground on the good component on the working board?
I am not sure that is why I am asking experts like you.
I am testing components after removing from board.
There are many of these same GA marking parts on board. All seem same pin 3 off all are common so I think they are all ground. But from main ground or even positive not showing continuity. For voltages I have not tested circuit powered up. Had to install it back in car. Temp fix is working fine but I am curious about this.
 

MrChips

Joined Oct 2, 2009
24,401
If it is a transistor in an SOT-89 package and the emitter at pin-3 is connected to GND then I would think it is an NPN transistor, not PNP.

1629566270031.png
 
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