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My first "real" board repair

DRANO

Super Member
Nov 15, 2012
2,821
517
113
Mississauga
Well, I succesfully completed my first true board repair :)
I've done small stuff but never had to diagnose or replace any major issues.

I reassembled my Addams Family on the weekend after months of being folded up with the head removed.
After a couple of games I blew F105. The fuse is for solenoids 1-8. I replaced the fuse, but now the game was going into some weird lock-up until it blew again. So the board had been compromised and/or a short was present.

I proceded to test all the coils 1-8 and noticed that the chair kickout was giving me a bad reading (under 2 ohms)... so I changed it.
I pull the board and found that the TIP102 at Q68 was fried. This one controls the Thing Kickout and not the chair... curious. This is a newer Rottendog board by the way. It's been in my game for years.

So, new coil, new transitor... I start to play. BTW, the rottendog boards don't appear to have pre-drivers, so I didn't change those obviously. The game is fine; it's playing great (God I missed playing my baby) and then I lock a ball at the Thing hand and boom... solenoids 1-8 are fried again. Replaced the fuse and I get the same short or weird lockup on startup.

With some guidance from our very own Menace, I pull connector J130 to those solenoids and turn on the game to see if it will boot normally... which it does. So, we've confirmed that the issue is on those circuits. Then I had to sound out each wire on that connector back to its corresponding coil... all good.
Lastly, Doug had me clip a wire to the offending coil (Thing Kickout since it was Q68 that kept blowing) and then plug the connector back in. Well, no short or lockup. So it seemed pretty certain that I was on the right track. But another repair later and the fuse blew again.

So, enter Doug and his mean schematic reading abilities:

Doug: "Does Rottendog have schematics online"
Me: "Yep, I think so"
Doug: "Wait a sec"
Me: "Okay"
Doug: "I found your issue"
Me: "Lay it on me"
Doug: "Rottendog boards use MOSFET transisitors, not TIP102. You need to get a 20n10L FET"
Me: :FP:

So, long story, but my grail pin is fine and working again :)

Moral of the story... read your schematics and never let me do any board work for you! I'm more comfortable with a paint brush in my hand than a soldering iron. BTW, I changed that coil too, even though it was testing fine, just for good measure.
 

Menace

Well-Known Member
Staff member
Nov 14, 2012
2,440
255
83
Santiago de Aurora
This one had me shaking my head because you were doing everything correctly. As soon as you mentioned you didn't notice any pre-drivers on the RD board I knew something was up. :)

Glad you got it all sorted!

D