Bally -35 missing half of controlled lamps

wrongdon

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I have a Silverball Mania that works and plays great except it is missing exactly half of the controlled lamps . I have swapped out the lamp driver board with the same results . All lamps have power to them . I have replaced the header pins on the Mpu and swapped out cpu and PIA chips with no change . I forget the exact count but believe it was 26 out of 52 that do not work , what could cause half the lamps the go out ? I am thinking it is a chip of some sort but which one ?
Thanks folks.
Don
 
The controlled lamp signals are "generated" through the PIA located at U10. Of course, you said you have changed the PIA, and the connector pins, so we have that covered.

Has there ever been any evidence of battery damage creeping up the side of the board that may have involved the connector? Did you make sure to clean the copper pads well before you replaced the connector? Have you also tried a different 5101 at U8? Has battery damage ever affected U8?

That's a start, let me know and we can go from there. Do you have a digital probe?

Chris
 
Thank you for the reply . It is a clean board with no acid damage , i have not tried another 5101 though i do think i have a few somewhere . I have a logic probe . I will swap out the 5101 and see if it makes a difference . If the PIA at U10 is in charge maybe i should change the socket ?
 
Definitely check the socket. Use your meter and put a lead on each pin of the PIA, and make sure you have continuity with the corresponding socket pin on the back of the board.

Even with no acid damage, these sockets can fail, as they fatigue and break over time.

I just swapped out the 6800 and *both* PIA sockets on a Stern MPU-200 board that had *zero* acid damage, but several flaky or flat out bad pins on each of the respective sockets.

I kept thinking it must be something else, but after swapping all three chips and verifying everything else was good, I decided to check the sockets and sure enough - all were bad...

Board fired right up with fresh sockets!
 
Thank you for the reply . It is a clean board with no acid damage , i have not tried another 5101 though i do think i have a few somewhere . I have a logic probe . I will swap out the 5101 and see if it makes a difference . If the PIA at U10 is in charge maybe i should change the socket ?

If the MPU board is working correctly, all the pins on J1 (upper right) should toggle when the board is booted into attract mode and the connector is unplugged. Yes, change your socket first, see what happens, and then check all these pins with your digital probe. Let us know!

Chris
 
I love just about everything about this hobby except changing sockets lol . I always hope it is something different . Thank you for the advice and i will update in a few days when i get my hands on some sockets .
 
It's not changing sockets that bothers me, it's changing sockets that have already been changed - poorly; the pads are all ripped up from the gorilla solder gun they used, and the ripped up pads have caused opens. Ack!!

Chris
 
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