This driver is an amplifier for both lamp and solenoid signals comming from the A1 MPU module. Usually, the transistors cause problems - it is rare, that you can find a defect IC. Do you see the diodes on the upper right? They were only used on the first generation of system1 games, which came with a xylophone. The coils for the xylophone are in line with the transistors, so the diodes had to take care of the transistors. Later, the xylophone was replaced with a sound card, so there was no longer need for them. If you have an early game, check your driver. These diodes are very important and if the driver has been replaced once, solder new diodes either on the driver or directly on the coil.

B) grounding and connection problems between driver an MPU:

OK, needless to say, this is a system1 game and of course, the driver has a bad ground. In my opinion, most of the drivers are working fine, but due to a corroded MPU - driver connection, the pinball does not work properly and so you might think, the driver is defect. Check the connection very carefully, most important is the MPU board connector at A1 J5. Also the connector pads on the MPU are usually corroded, thanks to the leaking battery. Remove your MPU and check the connetor pads on the solder side. Both bad connectors with broken or corroded pins or bad MPU board connector pads need replacement. Do not think, contact spray will help, things are even getting worse.

C) the solenoid transistors:

You can find three different types of transistors: For small coils, or to switch on 2 lamps at the same time the MPSU45 is used, for standard size coils you have 2N6043 or SE9300 transistors and for big target banks or a Rototarget the 2N3055 (TO-3 socket) was placed after a MPSU45. It is still easy to buy the 2N6043 (direct replacement: TIP112 or TIP122) and the big 2N3055, but it takes some time until you find the old MPSU45 by Motorola. A replacemant for this part is the BD679, but pay attention, you have to change the pins and bend 2 legs of the transistor (see picture on the left). Next comes a small overview, that might be quite helpful for you. It shows a transistor with the driven coil and the connector pin.

If a coil gets power from the driver all the time, you have to change the transistor (see list above). Pop bumpers, the slingshots are driven by its switch and not by a driver. If you have a stucked on coil on a pop bumper or a slingshot, please scroll down to E).

D) transitors and the ICs for the lamps:

Same procedure as every year, James, ahhhh, same thing with the lamps.... however the driving transistor is a MPSA13. If you always have 4 switched off lamps, follow the traces from their MPSA13 (see following list) to the 74175 driving IC. If it is always the same one, change it.

E) Other problems - coil/lamp still does not work:

Lamps, that do not turn on are often caused by corroded sockets or corroded or broken connector pins. I always forget to check the lamp - might be an easy fix, right?? Coils are not working because the coil itself has a short, the driving switch needs to be adjusted or the capacitor or the diode (both items are placed under the playfield) have shorts or else. Both pop bumpers and slingshots are driven by its own switch, so check the things above - that is all!! Again, check the connector between MPU and driver board. If some coils still do not work, you have a problem with the MPU module. See repair guide "Gottlieb system1- the Sys1 MPU".

© 2005 Nicole. Please report mistakes!

Please do not ask questions, that are already answered in the text:)