Gottlieb Solved Atlantis (Gottlieb, 1975) weak bumpers

[Sonora70]

I noticed the B relay is staying pulled after each time I fire either of the bumpers. I learned the bumpers are not pulling far enough to open the end of stroke switch therefore not allowing the relay to release. ( I know this because I can manually open the switch and the relay releases) It looks as though the bumpers are only pulling halfway. The coils are not locked up and seem to have smooth movement, my other coils seem fine as well. Any ideas of what's causing the lack of energy in my bumpers?

 

[Coil_Smoke]

After reading the manual for for this game(I Hope, please post exact year & Manufacturer). I deleted my original post here. I don't see EOS switches on pop bumper coil assembly. It says the coils are fired for 25 milliseconds by detecting 4 zero point crossings. I'm not clear if transistors or SCR's handle their current. But I guess either could be weak. Also phase detection diodes play a big role in some of the circuits that alternate to control 2 devices along with plenty other diodes in series and blocking that could affect coil power. This is a bit too complex to give you specific help. Spend more time studying those circuits as they are very interesting...C_S

 

[Sonora70]

This is a 1975 Gottlieb EM version.....sorry

 

[Coil_Smoke]

Do both pop bumper coils fire at the same time? If they are both weak the problem must be a poor contact handling the 25 Volts or maybe a bad(partially shorted) solenoid coil. Check the voltage at the coils while activated. Test the resistance of both coils. I think they are about 10 Ohms, whatever they should be almost the same. You can use your volt meter across closed contacts to look for potential across that contact. An open or bad contact will have a higher voltage across it, a good clean contact will show almost zero volts dropped across it while closed. Clean the contacts in that circuit path. Check the voltage at the coils again.

 

[Sonora70]

Atlantis weak bumper....Solved..

Well, a little embarrassed that I had made this post but I do want to follow up for anyone that may have a similar issue.
The issue that led to the problem required me to replace one of the bumper coils. When I picked up the game I noticed one of the fuses being blown and after investigating saw that one of the bumper coils was completely burned/jammed up. In fact, I actually took the coil out and used a hammer to try to get the plunger out of the coil and couldn't! I assume it had melted(welded) itself inside the coil. After replacing the coil and plunger I had the problem of the coils not pulling hard enough to contact the EOS switch. While trying to get the coils to fire properly I "cleaned" the switches on the bumper relay and thought the problem must be somewhere else. Today while reading the schematic I kept telling myself the problem must be between the switches at the bumper or the bumper relay. This time I removed the bumper relay AND the switches. On inspecting the switches I noticed that although I had "cleaned" them there was a layer of black on the switches. In short, a layer that required me to use a small metal file on them to clean. They now operate as they should....much more energy in the bumpers.

In short...lesson learned. Sometimes a quick cleaning of the switches may not be good enough. I assume the coil being stuck must have really burned the switch as well and it takes a bit more to remove the burned area on the switch.

BTW....thanks CoilSmoke for offering some tips.