Ok Everyone I need your help or at least where you think I should go next. I picked up a routed Pinball Party and overall it was dirty but in good shape. looked like the IO Driver baord 520-5137-00 REV G had been recently worked on by Stern as it had a tag, It looked like Q14 had been replaced which controls the upper Right flipper, upon game boot up upper right flipper doesnt work. Upon looking at the flipper coil fuse was not only blown but coil had been replaced with a 090-5030-ND 23-1100 which obviously didnt have a diode which caused the fuse to be blown and upon inspection of the MOSFET Transistor that Stern Replaced at Q14, it along with the small cap where both bad. Im sure what happened was they replaced the coil with a non diode one and it blew the fuse and transistor they then sent the boardset in not letting Stern know that they changed the coil with a NON Diode version and got the board back fired up the game and it blew again and they sold it.

So now I have the game I figure all this out I remove the Non Diode Coil,even Though it tests fine and I could just add a diode I figured lets replace it. I had a 090-5032-0T which is slightly less powerful and only 4.8 ohms versus the 5.3 Ohm standard one this should not be a problem correct?

I put a brand new diode on it and coil is tested fine, The wires are connected properly Blue/Black wire to the non stripped Cathode side and the Blue/Yellow wire to the center Cathode side center lug, this is the correct wiring. I also changed the Fuse that was blown to the correct replacement 3 amp slow blow. Next on the replacement would be the Mosfet Transistor at Q14 with a IRL540N direct cross reference replacement and the small cap that goes with it. I check legs after replacing making sure nothing is touching also continuity, traces etc and test the new parts everything is fine. I plug everything back in, Check it more then twice lol all wires, connectors etc and its all done properly.

So here goes lets fire it up it should work correct? Just kidding, Right off the power up the upper right coil is locked ON, I turn the game off instantly as I never took my hand off the power switch. i go check the fuse its not blown and then I check Q14 and OF COURSE its BLOWN OPEN as well as the cap is testing bad as well.

Ok so where do I go from here? I figured I had it under control as I went down the regular Checklist of this issue. Could it be the Chip at U2 failed on just the legs that control Q14? I dont know if that chip could fail partially and the other components that it controls could still work. If I disconnect the coil and turn the game on it plays fine just no upper right flipper. I have looked for open shorted wires, grounding issues etc there is nothing out of the ordinary. I have the socket and Chip for U2 as well as a new cap and Mosfet Transistor but dont wanna change all of that and be right back where I am right now.

So Now its up to you guys to help me, does anybody have any ideas or is there something I am missing? Thanks for reading my super long post but I wanted to cover everything I did rather then leave something out. I have repaired plenty of DMD style pins and this one has got me Stumped.

Thanks Again for any input and help.

Joe(acejedi)

I hear you on that but I really cant see that coil being the issue and doing all that work without knowing the coil would cause that. The coil thats in there is a stern coil that is found in all modern Stern/Sega games, why couldn't I use it, its a less powerful coil. You can upgrade LotR coils to bigger ones, the coil I replaced it with is a Flipper coil and the upper right Flipper is a full size flipper, I was just figuring it wouldn't be as powerful. Why would it cause the mosfet failure instantly? I could just see doing all that work with the original and the same thing happening. Either way thanks for your input. Where is everybody else? Come on guys I really need you on this one.

Joe(acejedi)

Im bumping this back up to the top I still need the help. Anyone?

Joe(acejedi)

Bumping it backup to the top anybody?

Joe(acejedi)

Yes the banded side of the diode has the blue/Yellow wire which is the power wire correct? Its wired the way your pic shows. I also tested the IC chip at U2 last night with a meter, just a basic test in diode mode and non of the legs look to be shorted open. Im Totally stumped on this one.

Joe(acejedi)

Yep the flipper button switch is fine because upper flipper playfield is working fine as well as the lower right flipper. This issue is a strange one, why would the Mosfet and cap fail when everything else is fine? Even though I tested the Chip I may change it anyways along with the coil to the original one with a brand new diode again and a new Mosfet and cap. If it blows and doesnt work then I guess its going to Rob to get looked at.

Joe(acejedi)

Well I fixed the game tonight, Put the original Non Diode coil that has the right part # on it with a brand new diode on it, Changed the MOSFET to a brand new one, Changed the Cap and Resistor that goes with that MOSFET at Q14. I also changed and socketed the Chip at U2, checked all the fuses and continuity and ground on the Yellow/Blue and Black/Blue wire and fired up the game with U9 and U10 unplugged to see if the Transistor got hot or the chip and it didnt, turned the game off plugged them in (fingers crossed) game back on nothing blew, Upper right flipper not stuck on anymore nice and cool transistor at Q14 and nice and cool chip at U2. Played a few games and all working like it should. Im happy and just wanted to post the results in case someone else runs into a similar issue. Thanks for the couple of people that responded to me need help ad.

Joe(acejedi)