T2 Target Drop Down Solenoid HOT

wolfievtec

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I have a T2 that keeps blowing F103. I've narrowed it down to the Target Drop Down Solenoid. With it disconnected the fuse won't blow and all other solenoids test fine. I replaced the solenoid with a new one and as soon as the game turns on, the fuse blows and the solenoid gets super hot. Could it be a driver board short? I've visually checked the wires for shorts. Thanks.
 
Assuming right coil, even though new it's good, wired in right, diode on it good. Next up I'd check the transistor driving it to see if it's the issue.

LTG :)
 
Sounds like 99% sure it would be the driver transistor. Coil #12 "knock Down" is controlled by Q52, test it with a multimeter. The way I do it is have the game off and test all the transistors that are around the Q52, and if Q52 tests different than the others it is bad.
 
Ok, here's the latest... I pulled out the driver board and it looks like Q52 has had some work done in the past. (Some jumpers on the underside of the board). I pulled a working T2 driver board and put it in. Same issue, blows F103 as soon as the machine turns on. Could a bad Q52 have toasted the solenoid and now it causes the fuse to blow? I'm out of good solenoids to try at the moment. Any ideas?
 
Assuming right coil, even though new it's good, wired in right, diode on it good. Next up I'd check the transistor driving it to see if it's the issue.

LTG :)


Good to see you here lloyd the Great!!
 
I don't see a diode on that coil. It looks like the only diodes are on the flipper coils. Unless they are elsewhere? I see one ones on the switches.
 
I believe for WPC they moved the diodes to the driver board. Anyway, check the resistance of that coil, is it less than 3 or 4 OHMS ? If so it is a dead short. And yes a fried transistor will keep a coil locked on till it blows. And also a blown coil will immediately fry a good transistor. So you have go to make sure both are good before turning anything on.

now you say it does it with another driver board, so what you need to do is check that coil.
 
Just an update.... replaced both the transistor on the board (Q52) and solenoid. Works 100%. Thanks for everyone's help! "LOAD THE CANON"!!! ---- GREAT SHOT!
 
Well, another bad update. The transistor Q52 blew again after a few days. I'm not sure what's causing it to blow. Any ideas to try next? I played about 30 games on it with no visible issues before it blew.
 
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