From other threads, I gather that some of the regulars here have some of the old manufacturers' parts books...

I'd like to see if anyone can help identify or narrow down the four Motorola TO-126 transistors in the lower right of this board.

I have an older version of this board that has two each of 2N4401 and 2N4403 in this circuit, which drives a motor at the end of a fairly long cable.

These TO-92 parts were clearly not always up to the task, so when the board was redesigned to use one EPROM instead of two, they also upgraded the motor drive circuit transistors to a more robust TO-126.

So, my question: What would have been a suitable 'general purpose' transistor with specs similar to the 2N4401 / 2N4403, but in a TO-126 package?

 

The real question is what is marked on the to-126 transistors? At least post a picture that shows them clearly. Without any indication of a part number, not much can be said. As to the specs, I would expect them to be different and likely more robust to handle more power/voltage if the 2N4401 and 2N4402 ones would fail regularly.

Dan

 

I haven't been able to find a picture that shows the part number clearly enough, and as eBay listings for this assembly are asking $400+ apiece for that board (or international shipping fees on top of the price), I'm not THAT curious.

Some searching has led me to conclude for now that the most likely candidates are 2N4920 and 2N4923.

 

Finally found a closeup where I could just discern the part number - I was VERY close.

The part number I read was 2N4921, so its PNP twin would be 2N4918. Case closed!

 

I finally broke down and bought the darn thing and the driver transistors are indeed 2N4918 / 2N4921.