Got my Eight Ball up and running a short time ago and I noticed that the 4 ball on the playfield and the 2 ball in the rack don’t light up. Changed bulbs of course, no difference. Jumped a wire from another working lamp socket and they both light up so it looks like the socket is good. Did the Anode test on the lamp driver SCR’s Q-57 and Q-26 and with the other end of the jumper grounded, both lamps light up, so I assume the SCR’s are good. I then checked the J1 and J-3 connectors on the LDB and noticed that both are missing the wires (according to my reading of the schematic) for those 2 lights. The guy I bought it from had hacked other wires so I’m guessing he did on these as well. My question is do I simply run new wire from the sockets straight to the appropriate connectors for both lights or do they go through another connection first? Also I noticed that a couple other wires were missing from the J connectors on the LDB yet the lights still functioned correctly, such as the 14 ball and 10 ball on the playfield, unless I’m reading the schematic wrong but I don’t think I am. Thanks for any advice

Thanks Cody. I see on the schematic, the wire color legend now. What would be the next move in your opinion?

Thanks for the info quench. Learning more quickly.

I performed the gate leg test like you suggested and the 2 Ball Rack (Q-26) lit up, however the playfield 4 Ball (Q-57) did not. Thanks for the helpful procedure advice. What do you think I should do next, regarding both lamps?

Checked the 2 SCRs with the DMM in Diode test mode as PinWiki suggested and with the red lead on the ‘G’ and the Black lead on the ‘C’, the Q-26 (2 ball rack) read .776, which was within the proper range and Q-57 (4 Ball) read only .262, which indicates a failure according to PinWiki. Sounds like I just need to replace the SCR on Q-57 but that still wouldn’t solve why the 2 ball doesn’t light properly. I’d like to know you guy’s opinion. And how easy/hard is it to replace a bad SCR?
Thanks for the help.

Did check all the wires going into the connectors and they all are where they are supposed to be. Sorry, I was mistaken earlier.

No. Neither the 4 or 2 ball light up in test mode. I’ve got the bottom pop bumper acting up similarly. The switch works underneath it but while it scores when hit, it doesn’t pop. If you run a wire from a Ground to the Q9 on the SDB it fires, so I know the coil is ok and not stuck.

Seems like replacing the SCR for Q-57 on the LDB seems logical since it tests low and the 4 ball won’t light even in the gate leg test you mentioned but I wonder what the problem is with the 2 Ball light, since it always lights up in testing and registered normal on the DMM but won’t light during gameplay.
Appreciate the help.

Here’s a picture of the LDB. I’m certainly not an experienced component solderer but I did successfully solder in a new rectifier board for this game thanks to help from people on Pinside.

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Thanks a bunch. Getting ready to start testing.

Just tested the legs on R-26 in lamp test mode and on DC got 0.00. Also did the same on R-57 (4 ball) and it barely registered 0.05. On ones that are working I get a reading that jumps all over the place but on the working lamps, they are all consistent that way.

Just tested the SDB like you said. Ran a jumper from TP6 to the lower leg of CR9 and the pop bumper did nothing. I noticed by accident when I touched the lower leg of CR-10, one of the other pop bumpers fired. This is awesome stuff to learn. I really appreciate the help. Let me know what you think.

On a side note: The lower pop bumper was working fine 3 days ago but the 2 lights in question have never worked since I bought the machine.

Looks like R-26 on the Solenoid Driver Board is cooked. Would that be in line with the bottom pop bumper and why it’s not firing?

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Just tested the U2 pin 5 for voltage and got 0.00. All the rest of the pins on U2 registered something, although I barely got any reading on pin 3.

Just tested the C-6 cap on the SDB on low resistance ohms and it measured 0.52 which was about the same as C-3,C-4,C-5 and C-6. They were all between 0.52 and 0.55.

I went ahead and ordered a small Tune up kit for the LDB and SDB from eBay so that I will have, resistors, capacitors, SCRs etc.... in case I need them later. I’m guessing that’s where we’re headed? What’s your opinion? I’ll have to wait if I want to take the plunge for new driver boards. I’m pinball broke right now :|Thanks again for all your help.

Wonder if not having the little diode on the lower pop bumper switch caused the transistor or resistor on the SDB to fail. The other 2 pop bumper switches have one.

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Green things capacitors? Not diodes I guess.

Thanks for all the responses. Checking soon

Got my solenoid and lamp driver kits and finally got time to work on the Eight Ball. Replaced resistor R-26 and transistor Q-9 and bam, bottom pop bumper is kicking ass. Now onto working on the Lamp Driver Board. Much obliged to you Quench for all your advice.

I also learned a ton. That’s invaluable for a pinhead. Thank you.