(Topic ID: 231317)

Jungle Lord 1981 Williams Drop Targets

By PinballGurus

5 years ago


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#1 5 years ago

I’m having an issue with one of the upper drop targets on Jungle Lord. All the others work fine, and I know the solenoid works because if I switch the brown/red signal wire to any other Drop Target signal wires it works. I’m stumped because I’m getting the proper voltage and it works when the wire is switched??? Any ideas would be greatly appreciated.

#3 5 years ago

Sounds like the switch of that target? you checked/cleaned that?

#5 5 years ago

Yeah. It looks fine and not only that it works in the same location when I switch the wire. I actually just replaced the transistors too and the voltage seems correct.

#6 5 years ago

Have you tried grounding the transistor tab for that coil?

#7 5 years ago

Yeah try that too, i dont have my JL anymore so i can cross-check my cables for ya, unfortunatly.

#8 5 years ago

I grounded the transistor tab and the drop target that isn’t working pops up.

#9 5 years ago

Still stumped? Anyone have a link to a repair or troubleshooting guide for Jungle Lord?

#10 5 years ago

Any other areas I should be checking at this point?

#11 5 years ago

If grounding the transistor fixes it then you have a board issue. If you've replaced the transistor and pre-driver next up the chain is IC3

#12 5 years ago

Yes, I’ve already replaced both transistors and same issue. IC3 is a chip issue?

#13 5 years ago
Quoted from PinballGurus:

Yes, I’ve already replaced both transistors and same issue. IC3 is a chip issue?

Yeah. It's either one of the bad components in the chain or a connectivity issue between them. You could trace the signal further with a logic probe and a test rom

#14 5 years ago

Hmmm... Since the solenoid doesn’t fire during the solenoid test and does when I ground it, then I can assume it’s a board issue? Like a cold solder joint, connection, or chip issue?

#15 5 years ago
Quoted from PinballGurus:

Hmmm... Since the solenoid doesn’t fire during the solenoid test and does when I ground it, then I can assume it’s a board issue? Like a cold solder joint, connection, or chip issue?

Cold joints are usually on the connector pins, but since grounding the transistor does fire it, that must mean it's getting through the connector fine.

#16 5 years ago

That’s what I was thinking. So...??? The chip then? Thanks for your help.

#17 5 years ago

This guy.. SN7408N

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#19 5 years ago

So before I changed out the IC 8 decided to check all the resistors and noticed one that was only reading .200 vs. all the others of the same code reading .550 so I checked continuity and that resistor connects to the transistor that makes the #2 drop target work when grounded. So I’m off to grab that replacement. I’m having doubts that IC is bad since everything else is working, but the one target, it’s not discolored, etc. and now I found that resistor. What do you think?

#20 5 years ago

Single pins on a chip can go bad, but if a resistor is measuring off that's definitely suspect

#21 5 years ago

Well I pulled that resistor out and it measured .210 in the board and .555 out of it. The new one I put in now measures back to .210??? Is that normal?

I finally found a schematic I could print so I’m going to figure out what IC it is that goes to the #2 Drop target before I replace it.

http://yumpu-download.tiny-tools.com/print.php?id=9038558

#22 5 years ago

What resistor number is it? I can check on one of my boards for comparison

#23 5 years ago

Thanks. It’s R56 reading .210ish. I appreciate it. Good thing I found the schematic. It looks like IC3 controls the drop targets. I’m going to go ahead and change it now.

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#24 5 years ago

Here goes nothing.

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#25 5 years ago

Guess what?... I pulled the IC and check the resistor and it’s back to .555 again. MUST BE THE IC!

#26 5 years ago

I really appreciate you helping me on this. Got it fixed. It was IC3 that was bad. It was also causing the resistor to read incorrectly; as when I changed out the chip it started reading correctly. Let me know if you ever have any issues with yours. Thanks again!

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