Quote Originally Posted by Melanie View Post
Just treat it as a high-gain NPN transistor. You can use any NPN power Transistor, but it's not going to work as well, and you'll need a reverse Diode across it for protection. For the purposes of test and playing with you could try it.
That's what I'm talking about. Just get control of the workings back. Worry about the complete fix after I get a TIP107...

Yes you have... "I've got another PRC2000 to do the rework".
And smoke another one! Maybe not...

remove each part, one by one and eventually I'll find the one that's duff (probably adding faults that weren't there in the first place).
Thing is, I had to pull a load of parts out anyways since they had been charred up by the initial burnout. Bad solder joint? Sure...maybe. While I was at the 2M class, they showed us some great X-ray video of cold solder joints. Shiny on top, cracked in the middle. I've got a decent handle on those...probably moreso than 99.9% of the rest of the hobbyist world.

My line of reasoning is this...
Oh, I agree completely...if it weren't for those charred bits/pieces that I had to pull in the first place. It could've easily been a bad joint on one of the biasing resistors that locked out the drive motor that that started the whole chain of events in the first place. But, I'll never know since that particular part was charred up...

The PRC is actually on hold for a couple of days. I blew up my tractor a couple of weeks ago and just happened to come across a new engine late last night. Putting it in tonight.
The final fix will come next week....at least it had better!!!