Quoted from Shredso:
How long can I run the displays with full voltage before I damage them? I was hoping I could run it for a few minutes at a time to troubleshoot some other stuff.
I would unplug them for now.
Good the filter caps are problematic if the old ones are on the board. They are past there life expectancy you and should be changed. Here is the standards for a solid working sdb that will not have you chasing issues.
5.7.6 How to Rebuild the Bally/Stern Solenoid Driver Board
The Solenoid Driver board is critical to the operation of the electronics of the game. The Solenoid Driver Board (SDB) comes in several types for Bally and Stern, and are completely interchangeable for any game of the 6800 MPU type. The SDB supplies the game with the voltages for the MPU, coils and high voltage for the displays. Recommendations are given below for replacing components to ensure proper operation and reliability. In all cases, do the ground modifications as shown in another part of this Wiki.
Minimum Recommendation for a Working board
At a minimum, replace both large capacitors on a working or non-working board, especially if they look original. Original caps are often metallic blue or metallic silver, and are at least 30 years old and due to fail, owing to the electrolytic chemicals in the capacitor drying up. The capacitor at C 23 has a factory value of 11,000 uf and 20 volts, but these values are not easily found these days. An electrolytic capacitor of between 11,000uf and 16,000 uf and 25 volts or greater can be safely substituted. A screw terminal capacitor makes for a easy installation, but a snap cap with leads can be used as well. Recent prices for screw terminal caps have increased greatly so this may be a factor in your decision.
The high voltage capacitor at C26 has an original spec of 160 uf and 350 volts and is an axial electrolytic capacitor. Once again, this part is difficult to encounter with these exact specs, but an axial or radial cap from 150uf to 180 uf and at least 350 volts can substitute. 400 v or 450v caps can be had in a radial format and size that will fit. With a radial cap you will have to make leads that bend back to the negative (-) solder pad.
Preferred recommendation for a working board
Clearly fractured .156 header pins on a Bally single sided driver board
Besides the above, replace ALL the .100 and .156 molex header pins and the connector terminals in the nylon housings with Molex TRIFURCON Phosphor Bronze tin plated crimp terminals (Molex Part# 08-52-0113 for 18-20 ga. Wire, and 08-52-0125 for 22-26 ga.) for the .156 connectors, and Molex .100 tin plated Phosphor Bronze crimp terminals, (Molex Part#08-52-0123). Do NOT skimp on this step and just do one or the other. The receptacles can be re-used if not burnt. If replacing the receptacles, the locking or non- locking ramp type are fine. Often, the connector at J5 does not cover the last few pins. I don’t like this personally, although no harm can be done if the key is in place.
Check every resistor that is usually covered by the plastic shield between the two big heat sinks for correct value and no sign of burn. Replace any that are suspect. Use the diode function on your multimeter to check the zener diode at VR1 and the 1N4004 diode. The zener diode can be difficult to source. See below for recommendation.
Gold Standard for Working or NON-WORKING board
It doesn’t make too much sense trying to trace down the exact problem and replacing only the bad components on a NON-WORKING board. Better to replace every possible bad component and start fresh. To ensure long life and proper operation of a working board, in ADDITION TO THE ABOVE, it is recommended that the components below are replaced regardless. Below is a list of components that effect the HV and +5 volt logic circuits on the SDB. Replace them all! * The Stern Revision J board is rather different, & a component list for that board follows. It can be identified by the extensive silk screening of each component and its function as seen in the 4th photo above, and by the HUGE 2 Watt and (2) large 1 Watt resistors. It is most often found on late date Stern games like Flight 2000 or Viper, etc.
Component replacement list for Bally AS2518-16 or -22 and Stern SDU100 SDBs, except * revision J
R51 22k ohm 1/2Watt
R52 390 ohm 1/4 Watt
R54 8.2k ohm 1/4 Watt
R55 1.2k ohm 1/4 Watt
R56 82k ohm 1/2 Watt
R35 100k ohm 1 Watt
CR21 1N4004 400PIV 1 amp or better (1N4007, etc.)
VR1 Zener diode 1N5275A 140 volts, 1/2 Watt. Can Sub 1N5275B or NTE 5099A
Q21 2N3584 250volts, 2 amp, TO-66 NPN
Q22&23 2N3440 250 volts 1 amp TO-39 NPN
Q20 LM323K (original 78H05KC or LAS1405)
C27&28 .01 uf 400 vdc metal polyester capacitor
RT1 25k ohm potentiometer (2 types) a 15mm black one, Piher Part# PT15LH06-253A2020 or a 6mm blue one BournsPart#3306P-1-253