Quoted from finalquest:Hi guys. First post here.
I'm restoring a getaway pinball.
I have an odd situation.
The controlled 555 lamps are barely visible through the playfields inserts. Specially on the darker ones.
I tried cleaning the inserts in the bottom playfield, but there wasn't any improvement.
I dont know how I can measure that the right voltage is reaching the lamps. The controlled lamps are flashing, so my Mulimeter cant get a correct reading
Check your +18VDC source voltage for the controlled lamps first. TP8 on the power driver board.
Quoted from finalquest:I have a voltage drop on the backbox GI. Without lamps I have a solid 6.8V. But as I add more lights to the circuit the voltage begins to drop. With all the lights I have 4.5V.
Can a Bad Triac cause this symptoms?
.
The triacs rarely fail, most likely something like poor connectors somewhere, an oxidized or cracking fuse clip or something along those lines causing a higher than normal resistance, as the circuit is loaded the GI supply can't quite deliver the current. The GI requires not only the voltage, but more importantly, good delivery of current. The PinWiki is loaded with some good info:
http://pinwiki.com/wiki/index.php?title=Williams_WPC#General_Lamp_Problems