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Switch 32 Trough 1 (WPC-95 Scared Stiff)

R

Roger

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10 Years
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Jul 21, 2011
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23
Hello all,
I wondered if anyone may be able to help with a new error message on my Scared Stiff?
It says to check Switch 32 Trough 1, which is one of the opto switches on the ball trough.
So far I have checked the LED is emitting a signal using an IR detector, which it is, and cleaned the LED's and receivers. I have also swapped both opto boards with spares I had; these emitted a signal too and I changed them both singly and as a pair.
In the backbox I have pressed the main WPC chip and U20 to make sure they are seated firmly and I have removed and reseated all the connectors on the CPU board.
Of course no joy so far and I still get the error message. The switch shows as closed all the time whereas all the others in the trough are open and activate properly.
I cannot see a short in the wiring and haven't had the machine open recently (prior to the error) to cause a short by physically moving or bending anything.
PinWiki mentions the subject briefly but only with regard to faulty opto boards; further investigation and diagnosis is not given.
It may be that the old opto boards I had (and my current one) are faulty, but the likelihood seems slim. It's about 50 Euros for a set (or $20 from US), so I'd like to try and diagnose the fault before trying the "do new parts fix it" approach.
So any suggestions would be appreciated, otherwise I'll buy the opto boards and give that a go.
Thanks,
Roger.
 
Assuming you have no other switch issues, as you have swapped both boards for presumed working ones and then it is likely not the boards. I would first be looking for a loose wire on the connector on the receiver board as you are getting a signal from the transmitter. Sometimes the connector wires can work loose and break due to constant banging of balls and vibration. Also check the connector pins on the boards for cracking around the solder as this is another common fault. Maybe both receiver boards have same issue.
 
Thanks for the replies.
There are no other switch issues (other than a long-standing issue where the crate eddy sensor occasionally registers hit after hit; switching off and on cures this).
I have ordered a new transmitter and receiver for the opto boards so will replace these individual components to be safe. (From what I have read the emitter needs to be installed with the flat edge opposite to that on the PCB, unlike the original emitters).
I will shortly reseat the IDC wiring connections at each end (maybe even replace these with decent crimped fittings) and reflow the solder on the CPU board pins.
I will update, thanks again for the help. :)
Roger.
 
If not that, next place to look is the 16 Opto PCB Board under playfield right hand side as optos route back to here. There is a schematic for it in the manual P3-19 (P132 of this pdf of manual https://www.ipdb.org/files/3915/Bally_1996_Scared_Stiff_Manual.pdf)

CPU board pins should be fine, as other switches in same column / row are working. It wa the pins on the receiver board that may be the issue.

Paul
 
Finally got around to fitting a new 16 opto board today. That has cured it. (Hopefully I'm not posting in a day or two to say it has recurred).
 
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