Austin, TX
I took my Data East Star Trek to TPF'18 for the umpteenth consecutive year. This year; after working well Fri & Sat; An attendee noted to me on Sunday that the Right flipper was stuck in the up position. I quickly checked the flipper switch and noted nothing wrong - the flipper was being held high under power. Turning off the machine allowed the flipper to fall. I turned it off for the rest of the show given it was only a couple of hours until show end.
Tonight I unpacked the machine and spent some time troubleshooting. At first; the flipper worked fine. Then during ball 3, game #1 the flipper started to hang. Sometimes pushing the button would cause it to reset. But now it seems to be hung there during the game after the first flip.
The flipper rests fine; and when flipped after starting the game; the red led on the Flipper board flashes and the flipper moves - yet, +8VAC hold voltage never disappears. Swapped the NAND ICs between left and right; the issue did not chase the IC.
Pulled all the transistors on the Right side of the flipper board and tested them with a DVM. All seem to be good. Resistors seem to be good. I did not test the SCR.
As I understand the schematics; Ground to the Flippers is thru the CPU board relay and the "hot" side of the coil is controlled via the flipper board. There are no shorted transistors possible on the CPU board.
I guess I could Shotgun the problem and just blanket replace all the Transistors; but I'd rather identify the possible problem and fix it.
Anyone have any ideas?
