Lost World

[Lystrade]

Hi everybody,
I'm new to the world of pinball and I am trying to repair a '77 Lost World. To begin with the knocker has been completely disabled because the machine tries to burn when it's connected. The out hole solenoid is the biggest problem though. It will not fire at all and when it's connected the machine blows two separate fuses. I need some advice on testing the solenoids, maybe a link to a datasheet on the an-26-1200 solenoid (out hole). I am an electrical engineering student so I have some small knowledge of electronics, but most of it is theory, I don't have much hands on experience.
Thanks

 

[Menace]

Sounds like the knocker coil is shorted, and likely it's associated driver transistor. All coils should measure over 2 ohms, any less and you're looking at a shorted coil. The outhole coil could also be shorted, and the diode on the coil could also be bad / missing which in turn would also destroy the driver transistor. Bust out your DMM and do some quick resistance checks on the coils, diode and transistor checks and you should at least get an idea of where the issue is. If you don't have the schematic for this game yet, try and find a hard copy or at the very least grab the soft copy from here; http://mirror2.ipdb.org/files/1476/Bally_1977_Lost_World_Manual.pdf

You will need the manual to figure out which drive transistors are for which coils. I mean you can figure it out on your own with a DMM and some time if you really wanted, but having the manual / schematics is just good practice. BTW, the knocker is controlled by transistor Q3 and the outhole coil is controlled by transistor Q4. (I just looked at the schematics)

Let us know if you have any other questions.

D

 

[Allan]

J4 on the SDU gets bad pins that generation had troubles with the little .092 pin connectors, a lot of problems start there.