I’m looking for a transistor, it has the part number TA790S 05CP printed on it but I can not find one anywhere online.

from what I can gather this part number no longer exists and I have to find the equivalent transistor?

Any help would be greatly appreciated.

 

Perhaps that is because it is a -5V voltage regulator.

 

It might be a 7905 regulator, what is the full pcb for?

 

It might be a 7905 regulator, what is the full pcb for?

Its the 4WD ECU from a Mitsubishi Showgun 3.2L

There is a fault in the 4WD and I’m told the bipolar transistor is the most likely cause.

 

Its the 4WD ECU from a Mitsubishi Showgun 3.2L

There is a fault in the 4WD and I’m told the bipolar transistor is the most likely cause.

Full picture of PCB…

 

Full picture of PCB…View attachment 304844

Could it be this one with 0667C 5 150 4L2 printed on it?

 

Can you test the transistor to see if it's faulty or not?

 

Can you test the transistor to see if it's faulty or not?

I could but I’d have to remove it from the board

 

What is supposed to happen, and why do you think that this is the problem.?

 

Shine some light on the part at an angle such that the writing is visible then take the photo.

 

Could be a 2SC5150.

 

The best way to get clear pictures of PCBs is using daylight (but no sun shining directly on).

A short session of testing using the same PCB will tell you the best combination at your place.

Focus, always focus.

 

The best way to get clear pictures of PCBs is using daylight (but no sun shining directly on).

A short session of testing using the same PCB will tell you the best combination at your place.

Focus, always focus.

Photo wasn’t taken by me, the owner sent me the photo after I had left and thought about asking for help here

I will get a better photo tomorrow morning. Good advice thanks.

 

2SD667

 

I could but I’d have to remove it from the board

You could try doing junction tests. I've had good success doing that in-circuit with an old school continuity checker (2 AA batteries and a bulb).

 

Here's a better picture showing a transistor on an EPROM programmer being checked.

You can see the bulb dimly lit above the DIP switch. On this board, there are no diodes or capacitors in parallel with junctions that might affect testing.