Black Knight 2000
Williams, 1989I have tried everything to get the left and right pop bumpers working. Even put in a new MPU. The switches are working and when I ground the tab they fire. Both have new coils and no diodes because the APS has the diodes on it. So new MPU, new coils, signal getting there, Whats left?
I know it sounds silly, but check the slow blow fuse under the upper playfield. (It can be seen in this picture right next to the rollovers. https://www.ipdb.org/showpic.pl?id=311&picno=35136&zoom=1). My Rollergames has a similar fuse and when it blows, the jet bumpers act screwy and the upper flipper becomes weak.
I did check that fuse and it is good and since ONE of the three bumpers work, that sort of confirms the fuse is good but thanks. Anyone else have an idea. I will be looking at it again today to try to figure it out.
Did you check for continuity thru both the backbox interconnect and upper pf interconnect boards? (Not just tone it)
I would also try and move the problem. IE: cross jump slings to pops(one pop to one sling via an undone connector), I use an alligator clip and a couple of old connector pins. I would cross check both switch and solenoid. If problem moves, you've eliminated pf.
Hope this helps.
I didnt know what else to do so I pulled the new MPU out of it, put it on the bench and tested the transistors again. Turns out, two of them were bad. They arent 102's or 122's but MOSFETs. Now I have to wait until I get the ones I ordered. I believe this will solve the problem. What probably happened was I installed the board without checking the coils. Should have checked them FIRST and THEN hooked up the board. Will know in a week or so if that was the problem. Game was fully restored and now it is sitting there not working!
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Freeport, FL
Vancouver, BC