Here is the short quiz from part 6 with an answer. Most of those who responded had the correct answer. Some did not, but I think it was because they did not read the question carefully.

Ok, I've only got one answer to this quiz question from part 6. I'd
really like to see all the students take a crack at answering it. Here
is a copy.

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Now while trying to peak T2 and T3 again I accidently bumped the ground
shield on my scope probe to the top part of R20 (the side not connected
to V+). Can anyone guess which component I fried when I keyed up, and
why? (This is homework ;-)
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See if you can figure it out!

Probably too easy. :-) 12V (or 13.8) from emitter to base of Q3 would
fry the junction - almost certainly open, unless your supply has a quick
current fold-back, in which case the junction might wind up shorted.
Not likely though. Also - it wouldn't matter if the rig was keyed or
not.