(Topic ID: 89692)

Coil always on with boards unplugged

By onetaste

9 years ago



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  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 9 years ago by dothedoo
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#1 9 years ago

A noobish question: I have an EBD that I'm trying to resurrect from the grave. I've just put in a new rectifier board - would you believe the old one had a couple of the bridge rectifiers wired off board screwed to a broken pool cue! At least it was in keeping with the theme

The problem I have right now is this: the target reset coil is always on the moment I turn on the machine. No other boards are plugged in (serious battery damage to a couple of them). Any ideas what might be causing this and how to attack it?

Thx!

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Post edited by onetaste: added photo

#2 9 years ago

Do you have pics of the old rectifier config? Off board rectifiers were common in EBDs, Centaurs and maybe other Ballys. They were wired in with two wires instead of four and the purpose was to drop the voltage a little bit on the GI circuit so the bulbs would last longer. For some reason these machines ran the GI at 7-7.5 volts before the "hack".

Are you saying all connectors are removed from the MPU, solenoid and lamp boards? The only connectors plugged in are on the rectifier board?

#3 9 years ago

The off board bridge rectifiers stuck to the pool cue look like a dirty way to replace rectifiers that had previously burnt out on the board. There are four wires coming off the board for each rectifier. No heat sinks on them, either.

There are some wires that are soldered directly on to one of the plugs on the sound board from recollection, I need to check this. Otherwise all boards except the power supply/rectifier board and maybe the auxiliary lamp board is unplugged.

#4 9 years ago

The bridges are functionally correct. Someone just moved them so they wouldn't have to remove a dozen screws if they ever needed to replace them again. The metal plate serves as the heatsink, which is correct. So if everything is disconnected you will have to investigate under the playfield and see how that coil is finding a path to ground.

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