(Topic ID: 116361)

Diodes on coils disconnected Williams FLASH

By Helixthree

9 years ago



Topic Stats

  • 3 posts
  • 3 Pinsiders participating
  • Latest reply 9 years ago by barakandl
  • Topic is favorited by 1 Pinsider

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#1 9 years ago

I just picked up a 1979 Williams Flash in pretty solid shape.

This is my first pin and i posted that i wanted a project, well it turns out this is a project but i need to ask a couple questions from you veterans.

All the diodes on the coils are cut.

What purpose does the diode have on the coil in this game? Could they function without?

All the diodes on all the coils are cut on the left side in a meticulous fashion. Any ideas as to why someone might do this?

Flippers appear to function after re soldering the diode and loading a credit, curiously the upper flipper also works, tho i have not reconnected the diode back onto coil below it on the playfield.

Located in Portland Oregon for anyone who cares to see it in person.

#2 9 years ago
Quoted from Helixthree:

What purpose does the diode have on the coil in this game? Could they function without?

Yes the coils will work without the diodes installed. The purpose of the diodes is to prevent a voltage spike from going back to the driver board and damaging components. Obviously for this reason the diodes should be re-installed.

No idea why someone would cut all of the diodes. On newer games the diodes are mounted on the board rather than on the coil. My only guess would be someone was "upgrading" the system. Does it look like any diodes have been added to the driver board?

#3 9 years ago
Quoted from terryb:

Yes the coils will work without the diodes installed. The purpose of the diodes is to prevent a voltage spike from going back to the driver board and damaging components. Obviously for this reason the diodes should be re-installed.
No idea why someone would cut all of the diodes. On newer games the diodes are mounted on the board rather than on the coil. My only guess would be someone was "upgrading" the system. Does it look like any diodes have been added to the driver board?

the solenoid bus does not go to the head of the game really. It would be a massive hackjob to add diodes to the driver board.

Someone was just being an idiot. Maybe looking for shorted coils or something.

Replace all the diodes, if a coil fires with no diode attach you will explode the transistor on the driver board.

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