TAF solenoid question

elfyhead

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so the swamp release and thing eject hole solenoids stopped working on my TAF. they're on the same solenoid power circuit, just connect to the drive via different transistors. the paper on the swamp release coil had burn marks, the sleeve was stuck to the coil, and it was reading no resistance across the lugs, so i went ahead and ordered a new coil.

it arrived today, and i just put it in, and no luck. turns out there is no voltage at the lugs. tested pin 1 on J106, which is the one supplying both of those coils (violet/green wire), and no voltage there. the other pins on J106 test fine (around +70V).

does this mean one of the drive transistors is bad? that would be Q20 for swamp release or Q24 for thing eject hole. my guess would be Q20, which could also have caused the coil to burn up i guess?

or is there something else i should check first? i hate to start desoldering the transistors from the power board to test them if i'm being stupid and not thinking of something simple that could cause the problem.
 
F103 was blown. thought i had tested it as good, but clearly not, as i got +70V on one side, 0V on the other. replaced that, and turned it on and the solenoid fired once, then locked on, and started to smoke. :/.

so, tested Q20 and Q24 and they both test bad. sigh.
 
well, crap. replaced the two TIP102's and 2N5401's this morning, and now the coil is stuck on. is the next culprit the 74LS374? and if so, is there a way to test it, or should i just replace it?
 
bump.

again - is this a 74LS374 problem and if so how do i test it? and, which one of the 74LS374's is it that goes with the swamp release circuit (and Q20)? i can't find a schematic that tells which of the U1-U5 go to which of the solenoid/flasher circuits (or anything listed in the manual).
 
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