help identifying a semiconductor

[generic user name]

Hi guys, i'm new here. Great site you have.
I'm having a little trouble locating a cross reference part or data sheet for a couple transistors.
Here's a little history if applicable:
I'm building a CNC machine, and i'm trying to repair the tool changer. I think i have traced the issues down to a transistor, or possibly all 3. I am limited in my electronics knowledge, but understand some basics, although i'm self taught.
Here's the part numbers:
f2n 4124 and f2n 4126. One is an NPN and one is PNP i believe. I can look later to see which one is which if needed. The board is circa 1980. Let me know if there's any more information needed. I have googled it, checked tons of sites, and still no info on it.
Thanks in advance!

 

[Mike_2545]

I searched for a 2N4124 and found this

**broken link removed**

 

[generic user name]

I searched for a 2N4124 and found this

**broken link removed**

Hmm that's a little too expensive for me.
j/k

Thanks, do you think it's the same component, more or less? I'm not sure what the f would stand for.

 

[generic user name]

I searched for a 2N4124 and found this

**broken link removed**

Thanks, i didnt try that partial search. I found a part locally that cross referenced that part number and soldered them in. It's losing voltage somewhere, but it doesnt spike then drop like it did before. checked a few resistors, but no luck yet.

 

[Mike_2545]

The f might be fairchild. A semiconductor brand.

 

[generic user name]

i think the rectifier is bad. it's a SCR. It measures about 55m ohms across the anode, cathode, and gate, no matter what direction i go. Seems fishy to me. Found some online, trying to find it locally now.

 

[generic user name]

yay it's all working. weird setup. apparently one coil on the impact gun gets ac current and the other gets dc, which gets it's polarity reversed to change direction. all this time i thought it was all ac. swapping the SCR fixed it.