Quite happy to be typing this post. This one was a tough one that I thought had almost got me, but here we are typing up the repair log.
I was contacted about a repair on a Williams Bram Stoker’s Dracula that was having multiple solenoids firing and was also receiving a ground short to row 2 in the switch matrix. When I got the machine in my shop, it wasn’t still ground shorting row 2, but solenoids were still firing all over at boot up.
Here’s the original video the owner sent of issues that were happening:
One of the most interesting and important features to this game is the Mist Multiball feature, but it also can cause a lot of problems if maladjusted or something is not working correctly with it.
The game uses a long beam opto for switch #82 to detect when docked at the right gate pocket, and where the ball is along the playfield on the under playfield magnet mechanism. If this opto isn’t functioning correctly, it can cause all sorts of mayhem with the Mist Multiball feature.
Without a ball in the right or left gate pockets in single switch test, switch #82 should read CLOSED. When you put your hand in front of the beam it should read OPEN. This game was constantly in an OPEN state.
I trouble shot a lot of the common issues with Mist Multiball including: replacing the receiver and transmitter optos, replacing the L1 inductor on the 24 opto board, and as much adjustment as humanly possible, but still no dice.
I ended up ordering the Homepin 24 opto reproduction board available here: http://www.johns-arcade.com/#!product-page/c1cs/59919533-df8f-8f79-cd42-49f29c39302d.
It’s a great upgrade on the original board (which uses several obsolete components) and even has a beam test LED which is quite handy. After still having issues, I took my questions to Pinside and with the gracious help of several members there started to make some headway.
I bench tested the Homepin board to ensure proper receiver, transmitter and board functionality. This narrows down issues in the circuit; however, when installed in game it still wasn’t working.
The long beam opto needs a 940nm transmitter and I’m guessing mine wasn’t to spec though I bought from a fairly well known pinball supplier. I had a Radio Shack purchased transmitter in my kit which was still in original packaging and definitely marked 940nm. I installed it and beam test was back working 100% in game, yet we still had an issue with the switch matrix detecting the switch as constantly open.
Turns out a loss of continuity on the red/white row 2 line was causing the last bit of issue in the puzzle. Once that was addressed, Mist Multiball was back up and running.
The other issues addressed on this game were some damage to the 10 opto board from the ground short which was from exposed wire to metal on one of the optos. It fried a 1N4004 diode and I socketed and replaced all three LM339s on that board. I also had several switches not registering that needed to be adjusted and popped in a new 2803 at U20 since the game had already had that chip socketed and the likelihood of damage from ground row short was high.
Only thing left is a couple of feature lamps not working and a repin of J120 on the power driver board which is burnt up nicely. After those quick, easy fixes I’ll have this game back to the owner. This one has been a long road, but a rewarding repair.