Attack from Mars
Bally, 1995I had just attempted to adjust a switch on the pop bumper and I must have done something wrong. It seems that I have two lines out on the switch matrix plus a message that there is a ground short on row 7. switches 16,17,26,27,46 and couple more are out.......
where do i begin?
Did you unsolder the switch and get wires crossed? Is something bent and touching each other or a metal bracket on underside of PF?
Probably obvious stuff you have already checked. Did you make adjustments with machine powered off? If not possible you touched something together with a tool and shorted it.
Quoted from Robo1:I had just attempted to adjust a switch on the pop bumper and I must have done something wrong.
If you did that with the power on you likely shorted high voltage to the switch matrix.
Remove the row and column connectors and see if the ground short error goes away. You can then jumper from one column to one row and the corresponding switch should indicated closed. Test all of the rows and columns this way. This will confirm whether you have a board or playfield problem.
So jumper from row 1 to column 1, row 2 to column 2, etc.
I definately shorted the switch to the back lug on the pop bumper coil. What components will I need to replace?
As soon as it happened I knew I had forgotten to turn off the machine after releasing the balls.......so stupid I havent adjusted any of my newer games in a long time and forgot the basics.....
Quoted from Robo1:I definately shorted the switch to the back lug on the pop bumper coil. What components will I need to replace?
There is no magic answer, do the test above and we'll start narrowing it down.
Do you have a logic probe?
I used the technique explained on the pinwiki site, and yes, there are entire rows affected. should i start by replacing the ULN2803 at U20? I can pick one up tomorrow at a nearby store, it is socketed so it would be a quick first attempt at finding a solution...
An easy start is to test switch column operation with your probe.
Here's how.
http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Quick_Switch_Column_Strobe_Testing
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Chris Hibler - CARGPB #31
http://chrishiblerpinball.com/contact.htm
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info
Here's some info on which logic probe to buy and how to use it.
https://pinside.com/pinball/forum/topic/terrybs-guide-to-logic-probes
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Luzern
Vancouver, WA