Quoted from jsa:quench and barakandl ... what do you make of this.
Alltek diagnostic board connected, same wiring/setup, either Alltek or Bally LDB, I can light individual lamps or entire SCRs with no blinking, one by one. That's the diagnostic board telling the MPU to light a lamp. MPU tells the LDB/SCR to turn on. No problem.
Game boots up normal code, no diagnostic board, Q14 gets those intermittent wave forms on the gate leg like this:
Your o-scope picture looks like the typical SCR not staying latched problem to me.
Just throwing out some stuff...
In testing i have noticed certain MPU200 games are more likely to show your flickering on the lower address lamps like yours. All i change is the MPU board from a bally game to Stern MPu200 and lamps may flicker.
Lowering the feature lamp voltage can make lamps flicker. More lamps on at once lower the voltage gets increasing the chance to flicker.
Extra load almost always can fix a flickering lamp. When i test lamp drivers with 680R load resistors I use a MPU200 game software that shows the most flickering. Then add any extra resistors to increase load as needed to keep a scr latched
Resistance in the connector contact that goes from the LDB connector to an actual lamp will cause flickering. Need a solid low resistance connection to the lamp or it may flicker. After so many insertion cycles on my tester the plating of the female pins starts to rub off and the lamps begin to flicker. I repin the plug and it goes away.