Bally Eight Ball Deluxe Limited Edition (Bally, 1982) Thumper Bumper

[nwkadm]

Having weird issues - As I was looking under the playfield on my EBD -LE, I noticed that the 2 yellow wires going to the center Thumper Bumper were loose. I resoldered them (3 times so far) and now I am having weird issues such as the 2x, 3x. and 4x drop targets will not score when dropped, the thumper bumper will fire on it's own causing the 4x light to light up, the left flippers sometimes get stuck.
I tried to resolder these connections again and when I went into test mode, switch 03 (4x target) light up as bad. I resoldered again (3rd time) and now the 03 no longer lights up during test but still have issues.
Does any of this make sense - I am thinking there is something in common with these wires but and not able to determine what it is.


Any help is appreciated!

 

[Coil_Smoke]

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Is here something amiss with that switch assembly? Like the stiff blade touching or fish paper allowing a short. Did the blocking diode get cooked? Try removing those wires to isolate the problem. It is so easy to cause other problems while working under play field, like breaking a solder connection. Those drop target issues sound like a broken connection in switch matrix. I like to start switch edges test then operate switches and wiggle everything. Look for sparks, blobs of solder/loose hardware in bad places, screws worked loose in switch stacks Etc....

 

[nwkadm]

Coil Smoke -

When you speak about fish paper allowing a short, blocking diode got cooked, switch matrix - where do I look for the fish paper? What/where is the blocking diode and how would I measure to see if bad? Where do I look or what is switch matrix?

Sorry - newbie to all this.

 

[Coil_Smoke]

"Fish Paper" is the brown durable paper insulator separating blades in switches. I imagine the diodes are soldered directly to the solder tabs on each switch. They absorb voltage spikes and stop switches from interfering with others in the matrix. The switch matrix, Page 23>>> http://mirror2.ipdb.org/files/762/Bally_1981_Eight_Ball_Deluxe_English_Manual_includes_paginated_schematics.pdf and lamp matrix are used to reduce the number of wires and connectors. They consist or columns and and rows with the switches forming junctions between one column and one row. The computer is always rapidly scanning the switch matrix looking for closed connections. This works well in pinball games as the ball never closes more than one switch at a time. Diodes can be checked with ohm meter or even a continuity tester. They are either working, open or shorted. A working a diode only conducts in one direction and blocks current flow in the other direction.
P>S> I see some capacitors across some of your switches. They also absorb noise from contacts making/breaking possibly feeding back to MPU. Those little capacitors[Basically] should read open on low ohms range. I suppose they could have intermittent shorts, possibly thermally unstable?

 

[Coil_Smoke]

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