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Pinball Rehab

pinball repair and restoration

Dracula Mist Multiball Dracula Mist Multiball Hot video

While a very cool toy, the magnet mechanism on Bram Stoker's Dracula can be a challenge to troubleshoot. The first step is to run through the magnet diagnostics (the attached video provides an overview of the Mist Multiball system and the magnet diagnostics). This info combined with your observations during game play should get you pointed in the right direction most of the time.

Download mist multiball schematics here.

There are a few problems though that can provide erroneous error messages in the magnet test or display themselves in bizarre ways. For example, failure of the long beam opto can cause false end of ball conditions or multiple balls on the playfield (like a bad trough switch). The rest of this document will cover a few tips and tricks relating to troubleshooting and repairing the Dracula Mist Multiball toy.

Cables

It is not uncommon to have problems with the coiled cable that goes to the magnet.  Cable problems can cause the magnet to not work or move the ball partially across the playfield and then drop it.  Test the cable with a DMM in diode/continuity mode while wiggling it.

There are two small boards (magnet power supply and motor EMI board)  in the upper left portion of the playfield (when it is in the raised position).  The connectors are easily pulled loose if the wire bundle catches on something while raising the playfield.

Right Gate Bent

If the gate on the right staging area (where the ball is stored) is bent the ball can rest lower on the playfield that it should be. This can cause problems with either the long beam opto or the short opto for the right staging area.

Long Beam Opto

The Ball on Magnet switch (#82) long beam opto transmits a modulated 40Khz infrared beam and the receiver detects this signal. This is different than short beam optos, which are normally on (high) unless blocked by a pinball or other device. Simply checking the transmitter and receiver voltages does not guarantee the long beam opto is working correctly, the signal must be pulsed.

Normally your first indication of a long opto problem is the magnet will release the ball shortly after it exits the right or left gate (of course a magnet problem will also cause the same symptom). The most common cause is the L1 inductor separating from the 24 switch opto assembly. I presume due to vibration, but in any case it's not uncommon to find the inductor in the bottom of the cabinet.

There seems to be a lot of confusion about the correct replacement part, you can purchase the correct inductor at Mouser though this link. The Mouser part number is 434-03-103J and the manufacturer's part number is 11P-103J-50.

If you're not that lucky, keep reading.

If you suspect a long opto problem, enter diagnostics and go to single switch test mode. Then scroll through until you get to "Ball on Magnet." If there is a ball in either of the mist multiball gates, remove it.

The switch should read closed and if you place your hand across the beam it should then read open. If the switch never reads closed there are a couple of quick tests you can do. First check the receiver by placing a tv remote in front of the sensor and pressing any channel (numbered) button. If the receiver and its associated circuitry is working the display will briefly signal the switch is closed.

If the receiver side is not working the first step is to check the opto alignment. The long beam opto sender LED (white case) should be adjusted towards the front of the game. It can be adjusted by loosening the two screws holding it in place and sliding the white case towards the front of the game. There is really no other good way to check the opto alignment other than using an infrared detector card from MCM electronics.

If the receiver side is working, check the transmitter and its associated circuitry by enabling the camera on any digital phone. Place the camera lens in front of the gate and you should see a white glow (like a small LED or bulb) where the transmitter is. You can verify this test works with your phone by using a tv remote, as explained above, pointed at your phone's camera.

Important: This test only indicates the transmitter is on, not that it is sending a modulated pulse. The only way to accurately check for a modulated pulse is with an oscilloscope.

If the LED does not show up in the camera test the problem is either the opto LED or on the 24 switch opto assembly. If the LED does show up in the camera test but the circuit never reads closed the problem is most likely on the 24 switch opto assembly.

At this point you should know if you have a problem on the receiver or transmitter side and can work your way through the circuit until you find the problem.

Homepin.com makes a replacement long opto board that has been redesigned since one of the IC's is obsolete (see this article).

Short Beam Optos

The most common problem with the short beam optos is due to interference from controlled lamps or flash lamps. If Opto Check 1 in diagnostics fails, the problem is most likely with the opto alignment. Verify the sending LED and receiving opto have not moved in their white/black housing and are pointing at each other. The receiver and transmitter should be firmly soldered to the circuit board with no exposed wire between the component and the board.

If Opto Check 2 fails the most likely problem is the shielded cable is not properly grounded. Verify a good ground connection with an ohmmeter.