Black Hole
BH ball lift kicker mod
The problem as I see it (Steve Charland)
From an engineering standpoint, the upkicker for BH is a simple and direct design but it does have it's slight faults. The first being that there is no way to adjust the power of the kick from the lower playfield to the upper playfield. The second is the problem of the ball lift coil getting fried. This happens all too often.
The solution/s
I'll address the first problem. The way most commonly used to adjust the ball lift coil is to take some windings off to weaken it so the ball will not travel too fast to the upper playfield and hit the glass. I wanted something a little simpler and I also wanted to have more control as to how fast the ball could travel. The solution is simple, add a end of stroke switch to the coil. Because the switch can be adjusted to open early or late, you can control the force of the hit to the ball. Open the switch early and the ball travel is slower, open the switch late and the ball travel is fast. Full power if the switch stays closed or is not used. Making the end of stroke switch bracket isn't too difficult to do; just contact Cliffy and hopefully he'll have them for sale soon.
Now ... on to the A-4893 coil getting fried. There is something to note here, the schematic calls for a 6 1/4 amp Slo-Blo fuse for F17. A 6 1/4 amp Slo-Blo passes way too much current to protect the ball lift coil should either drive transistors lock on. No wonder it cooks. This coil needs to be protected with a 2.5 amp Slo-Blo fuse, just like the pop bumper coils (so the fuse blows before the coil cooks).
If you're still worried about the coil getting cooked, use a A-20095 flipper coil instead and use the newly installed end of stroke switch to shut off the stronger internal coil. This way, if either drive transistors should lock on and fire the ball lift coil, the hold portion of the flipper coil will be the only thing the transistor drives (just like a flipper).
- Various display issues resulting from failed 6264 RAM
Measuring to determine hole placement. 
Completed work, flipper coil installed. 
Marking the holes. 
The bracket and switch in place. 
The new bracket and switch. 
Another view of the new bracket and switch.
