(Topic ID: 261662)

1974 Williams Skylab fuse question

By Peruman

3 years ago

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  • 4 posts
  • 3 Pinsiders participating
  • Latest reply 3 years ago by Peruman
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#1 3 years ago

I need some help getting this question answered:

I finished working on a Skylab to deliver to a friend. This is the first game I have fixed to sell to someone else. After setup, the game worked for about 10 minutes when it shut down completely. Checking the fuses, the 15 Amp fuse on the 24V line had blown (red arrow on schematic). Losing 24V took out the Lock Relay which controls the two 6V lines (highlighted in yellow). When I pulled the fuse on the 24V, 15A spot, it was the fuse in the picture below. It's a 5A fuse!

Here is my question, how can a 5A fuse handle being on a 15A circuit? I ran this machine through a lot of games after I finished fixing it before delivering. I had no issues - please help me understand what could have happened.

I felt awful - way to deliver a giant paperweight.


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#2 3 years ago

Could be a slow blow fuse. Which can handle a higher draw for a short period of time. Here is a of a regular 5 amp beside the slow blow fuse in the package. The fuse will blow if the amperage being pulled by the pinball machine is greater that the rated amps. Slow blow will allow for a spike of amperage without blowing (like the start up of a machine). If you draw more that the rated amperage for an extended period the slow blow fuses will blow.

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#3 3 years ago

Install the correct sized fuse per the schematic. If it doesn’t blow, you’re Ok.
The size of the fuse is the max draw under worst case situations. You’re very likely going to draw less during a few games, do I can imagine that you’d get away with a slow blow 5 amp for a while.


#4 3 years ago

Installed the correct 15A fuse and the game started right up. Thank you for the help

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