BALLY TWILIGHT ZONE SWITCH ISSUES

[Gern Blanston]

I have a Twilight Zone Pinball where one column 5( Green-Black J206-5) is also actuating the switches in column 1 (Green Brown J206-1)

for example:
In the switch edge test mode...
I press Slot Kickout 58, and Outhole 18 also actuates,
I actuate Slot Proximity 57, and Left Trough 17 also actuates
Gumball Exit 56, also actuates Center Trough 16
etc...

Any Suggestions?

 

[Poibug]

first point of call inspect cpu board for ANY sings of corrosion from leaking batteries (past or present)

 

[Jay Walker]

Hi, Gern,

The two columns operating simultaneously may be caused by a fault on the cpu board, or by the wiring for the columns being shorted together somewhere on or under the playfield.

One way to determine which is to detach the connectors for the switch matrix from the bottom of the circuit board. Leaving the connectors for the cabinet, especially that for the 'Direct' or 'D' switches, which AIR has orange w/trace colour wires, still allows access to the test routines. Though booting-up the game without the playfield switches often brings up other apparent 'problems' such as ball missing errors, or probably Gumball Errors of some kind on Twilight Zone.

Anyway, ignoring for the moment any such additional issues, get into the switch tests with the playfield switches out of the picture. Since this is a special case, it's alright to simulate the affected playfield switches simply by using a length of wire between the relevant pins of the vacant connectors for rows & columns, e.g. jumpering the pin for col. 1 to that for row 8 should only register as 'Outhole'. If so, then the problem lies with the playfield. If no change, then it's likely to be the circuit board, since I don't think both these cols. (1 and 5) are used in the cabinet.

 

[Gern Blanston]

Hi Jay...
My name is actually Bob..Gern is just a goofy name I use on the internet
The troubleshooting test you recommended worked like a charm..With 206 and 208 disconnected and using jumpers to simulate closed switches, I was able to rule out the CPU board,as only one "switch" actuated at one time. So I proceeded to try to find the short..I narrowed it down to the Right Trough Switch..The only time "multiple switches" are activated is when the Right Trough Switch is activated. I then disconnected the ground wire on the suspected switch for a diode test..The diode checked out good..Do these micro switches go eventually short out or go bad?

 

[Jay Walker]

Hi, Bob,

It's similar with me, my name's david, but JW is a nom de plume which refers to how I sometimes feel about the 'information superhighway'. D'you mean that the problem with other switches occurs when the Right Trough switch is closed, i.e. with a ball sitting on it?. The thing about a switch 'matrix' is that while it saves on wiring & connector proliferation, it's vulnerable to bad diodes, which can cause strange problems. What may be happening here is that the Right Trough, while being okay itself, completes a 'rectangle' of closed switches, with the bad diode/switch being diagonally opposite. Though this case usually shows as only one 'phantom' switch, not a short between columns.

The micro-switches don't have an infinite lifespan, and there were quality issues starting to creep in at the time - I've heard that Scared Stiff is notorious for failed switches. Take the diode off the switch (if you haven't already done so, just at one end will do) and make a check of the bare switch. The 'Com'(mon) terminal should only connect to one of the others at a time; 'NC' with the switch 'open'/no ball present, 'NO' with the switch 'closed'/ball present, NOT both at once, or between them.

 

[Gern Blanston]

On the right trough switch...I disconnected one diode end and tested...Checked good...Tested the microswitch..also good...Like I said the only times multiple switches activate is when a ball (or I am manually actuating the right trough switch)
I am confused where to go from here

 

[Jay Walker]

I'd check the entire row (#5) and the affected columns. I see that there are some optic switches involved, such as one of the lock switches and mini playfield top, besides the trough prox. Try it with all of these eliminated by disconnecting their circuit boards - the ones which link them into the switch matrix.