Addams Family Gold (Special Collectors Edition), The
Bally, 1994
Addams Family, The
Bally, 1992Hey guys i picked up this TAF about a month ago and the left side magnet was stuck on and was unplugged. Well i replaced the transistor on the driver board and it worked good for about a week, then i notice the magnets arent as strong and find the left one had stopped working. Replaced the transistor and it was back up and going, well its been a week and i think its blown again. Haven't checked yet, but what could be up? Thanks
Do you have the fuse mod installed?
http://www.pinballlife.com/index.php?p=product&id=1170
That might not fix the actual cause of the problem, but may protect the transistor from being destroyed. If you solder/desolder a pad or through-hole too many times, it will come off the PCB.
Quoted from ForceFlow:Do you have the fuse mod installed?
http://www.pinballlife.com/index.php?p=product&id=1170
That might not fix the actual cause of the problem, but may protect the transistor from being destroyed. If you solder/desolder a pad or through-hole too many times, it will come off the PCB.
The fuse kits are there to protect the playfield, not the transistor. If the transistor locks on the magnet gets hot and can burn the playfield (almost always the left one, not sure why). I fused my magnets before I loaned my game to a family member. The transistor failed and the fuse blew saving me from magnet burn. I started making the kits for Terry but got tired of making them after 200 - 300 sets so he is getting them from someone else now.
Yes i have the fuses installed, i haven't checked to see if it was that this time or not. But yea thats not going to protect the transistor, only going to protect the play-field. I have not replaced any diodes, is there some on the same board with the transistors?
Check the resistance on the magnets and make sure they are all the same. If the magnet is shorted then it will blow the transistor.
When you say change the transistor, I presume you talking about the under-playfield transistor?
Quoted from trab:Ill check the magnet in a minute but wouldn't it blow the transistor instantly?
It could be a partial short rather than a dead short. Also check the wiring to the magnet and make sure it's not rubbing up against something.
Quoted from trab:Yes the ones under the playfield. Ill check the magnet in a minute but wouldn't it blow the transistor instantly?
Did you check Q44 on the driver board (and it's pre-driver)? That is the transistor that drives the transistor on the board below the playfield.
I didnt check the q44 but i will. I just checked the ohms on the magnets and the one that is giving me trouble measured right at 5.8 and the other two measured 6.8, i was reading a thread where somebody else said theirs where all around 5 ohms. Not sure if that means anything or not.
Quoted from trab:Ok i just checked the q44 transistor and compared it to the q32/q34 of the other magnets and they are functioning identically. What is the pre-driver?
Have a crappy schematic I'm trying to read and I think the predriver for Q44 is Q43. Should be obvious when you look at the board.
Ok i will check that tonight, i think im going to replace the transistor again on the driver board under the playfield. Then change the magnet it drives and see if it fails again, that would rule out the magnet being the problem at least.
Quoted from trab:Ok i will check that tonight, i think im going to replace the transistor again on the driver board under the playfield. Then change the magnet it drives and see if it fails again, that would rule out the magnet being the problem at least.
I think that's a good plan. The 1 ohm difference could make as much as a 1 amp difference in current (not compensated for the pulse width).
Do you have a logic probe?
You've replaced the magnet (or swapped it with another one) and replaced the driver transistor? If so then about all that is left is the pre-driver transistor, the pre-pre driver or the logic circuit. The magnet circuit should be pulsed so if it is locking on rather than pulsing hi/lo you will draw too much current and blow the transistor.
Quoted from trab:Well the magnet seems to pulse just like the others when in test mode. What is the logic circuit?
U4. It would really help to have a logic probe at this point.
Also just to confirm, you did either replace or swap the magnet? If you did I presume you still have the same playfield wiring from the backbox to the transistor board and from the transistor board to the magnet. If so I would check (with game off) both wires for a partial short to ground. This may not work since it is so intermittent, but it's worth a try.
Quoted from Mamushka:Have a crappy schematic I'm trying to read and I think the predriver for Q44 is Q43. Should be obvious when you look at the board.
Its been a long time and i finally got around to checking this out. The predriver seems fine, it functions just as the others do. I did find that one of my ground wires in the backbox was disconnected so i fixed that, but im not sure if that was causing any problems. Looked to just be running from the key at the top down to a few brackets that hold the swinging light door in the back then to the big metal board in the backbox.
Ok guys i did some more checking and feel like a idiot. It looks like one of the legs i soldered on the transistors, the one that gets the 60+ volts was melting the solder off the leg. Not enough to where i could see it, just enough not to make contact. I think my poor solder job was to blame, so i did a better job this time around and i believe that my problem is now fixed. 
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