Recently acquired a Jokerz. it had a missing GI Relay under the playfield. I purchased a NOS C-11998-1 board and installed it. after power up, Q9, the GI driving transistor exploded.
what could cause this?
this is my first sys 11 fix. i am familiar with driving transistors for normal playfield solenoids, but not familiar with GI relays.
thanks in advance.
-barry

I checked wiring and it was correct. i went back to the manual and realized the replacement NOS relay board was actually a C-11902-1 (motor relay board/center ramp motor relay), and not the GI relay C-11998-1. they sent me the wrong one :/

I still need to investigate further what else was affected, but at first glance: the three drop targets, outhole, and the shooter lane solenoids do not work. (they did work before the Q9 transistor blew)
im hoping it is just the associated transistors, but guessing its deeper. it looks like the ones that dont work are the "A" side of the A/C select relay of the switched solenoids.
any insight into the predicament is def appreciated.

I plan on taking mpu out later and testing all the transistors, but after reading your response I remembered a possible clue.
*The moment q9 exploded, the flashers flashed once as well.

no real sucess yet but progress:
*i switched the new relay with the GI relay board in backbox, and the backbox GI lights lit up as should. So to my surprise, it seems relay i was sent was actually an okay replacement, and did not create this issue.
*I did switch test and it told me C power for AC relay was stuck on. That would explain why the A side relays are not working. Through reading, it sounds like C power being stuck on is probably caused by a blown transistor for AC relay. I need to confirm but i read its usually Q8, which is next to Q9 that exploded, so that sounds pretty reasonable.
*i had ordered tip122s to replace blown ones, but now have read they should be replaced with tip102s, which i think i have. I also found a 7408 (U19) incase it gets to that.

So, it seems once i get bad transistors replaced, my main predicament is making sure this doesnt happen again. aka, for some reason plugging in playfield GI relay blows GI relay transistor. what should i be looking for as far as "bad wiring" goes? the connectors at the relay are correct and look fine.

it was a few unrelated incorrect wiring issues.

the coils were daisy chained wrong and AC relay transister didnt blow till ball landed in upper left kick out. thats why outhole and others had worked till then.

I havent gotten to the bottom of the GI issue, but is totally unrelated to coils not working. i appreciate the help.