Aussie Pinball Forums > Circuit Board Repair Guides
Old Bally / Stern displays
Pinball Fixers:
If you own an old Bally or Stern pinball, then having working displays is a must...
Every now and then, one of the digits (numbers) on a display will disappear completely. Thankfully, it is usually a really easy fix...
Most of the time, it is a resistor that has gone open circuit. There are 6 (or 7 in the case of a 7 digit display) 100k ohm, 1/4 Watt resistors that are part of the power circuit for each digit.
These resistors are getting quite old now, so they should be replaced to ensure the display continues to work.
Once they are any more than 10% out of spec (110k ohm or above), they are on their way to failure...
When replacing these resistors, use 100k ohm, 1/2 Watt resistors. Or better yet, 100k ohm, 1 Watt Metal film resistors. Metal Film resistors are often around half the physical size of a standard carbon film resistor, so they can handle more heat in a smaller package.
The resistors marked above are as follows (6 Digit Display):
R1 - 1's Digit
R3 - 10's Digit
R5 - 100's Digit
R7 - 1000's Digit
R9 - 10,000's Digit
R11 - 100,000's Digit
On the 7 Digit Display, R56 is used for the 1,000,000's digit - 100k ohm resistor also.
Creech:
Thanks for that mate. Once again, a valuable guide for our members.
Strangeways:
R34 is also a 100K Ohm resistor, and I change these as well. They can eradicate the "flicker" that sometimes affects these displays..
The changing of the digit resistors should be manditory - as Owen has pointed out.
Reflowing the headers pins abd the display pins solves most of the problems with these displays..
My apologies for preempting anything points you wish to make, Owen - I actually enjoy repairing displays.. I used to buy them faulty off eBay just for the fun of repairing them !!
Pinball Fixers:
--- Quote from: Strangeways on December 18, 2008, 11:12:28 PM ---
My apologies for preempting anything points you wish to make, Owen - I actually enjoy repairing displays.. I used to buy them faulty off eBay just for the fun of repairing them !!
--- End quote ---
No probs Nino. I was hoping you (and others) would chime in with other fixes for these displays... I do have some more points to make on them though.
Pinball Fixers:
--- Quote from: Strangeways on December 18, 2008, 11:12:28 PM ---
R34 is also a 100K Ohm resistor, and I change these as well. They can eradicate the "flicker" that sometimes affects these displays..
--- End quote ---
I've updated the picture above to show where the R34 resistor is.
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