(Topic ID: 255113)

WPC 95/NGG blowing fuses 103/104 after PS repair


By tamoore

14 days ago



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  • 9 posts
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  • Latest reply 14 days ago by LTG
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#1 14 days ago

My NGG has had a reset problem for quite some time.
I've replaced the rectifier diodes previously, which didn't fix it.
I just replaced the capacitors at C8,9,10,11 and 12.
Good news: I can activate both flippers without the game resetting.

But...

Now when I turn the game on, 50v fuses 103 and 104 blow. 102 is fine (coils 9-16).
Nothing blows with the J133 connector unplugged.

Any ideas on where to start looking? It doesn't seem like the capacitors I just replaced would have an impact on the 50v.
Thanks.

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#2 14 days ago
Quoted from tamoore:

My NGG has had a reset problem for quite some time.
I've replaced the rectifier diodes previously, which didn't fix it.
I just replaced the capacitors at C8,9,10,11 and 12.
Good news: I can activate both flippers without the game resetting.
But...
Now when I turn the game on, 50v fuses 103 and 104 blow. 102 is fine (coils 9-16).
Nothing blows with the J133 connector unplugged.
Any ideas on where to start looking? It doesn't seem like the capacitors I just replaced would have an impact on the 50v.
Thanks.[quoted image]

I'd suspect a short on some of the coils first, check the area around each one and make sure nothing's touching

#3 14 days ago
Quoted from dudah:

I'd suspect a short on some of the coils first, check the area around each one and make sure nothing's touching

That's a good thought and something I considered, but other than the random reset, everything was working perfectly before I changed out the capacitors. Never took the glass off. It would be quite a random coincidence for two different 50v strings to be shorted out at once.

Thanks!

#4 14 days ago

Ohm out those wires on j33 you should find the issue.

#5 14 days ago

Verify that you didn't reverse the polarity on any of the replaced components.

#6 14 days ago
Quoted from ForceFlow:

Verify that you didn't reverse the polarity on any of the replaced components.

They're all pointy the same (correct) way. Thanks for the idea!

#7 14 days ago
Quoted from tamoore:

They're all pointy the same (correct) way. Thanks for the idea!

Just as an FYI, sometimes older capacitors mark the positive terminal, rather than the negative terminal. However, I'm pretty sure on WPC/WPC95, they're new enough that all of them mark the negative terminal.

#8 14 days ago

If you replaced any resistors, measure them with a multimeter to verify their value. It's possible that they might be off, or the wrong one ended up in a batch by mistake or through sorting/handling.

#9 14 days ago
Quoted from ForceFlow:

Just as an FYI, sometimes older capacitors mark the positive terminal, rather than the negative terminal. However, I'm pretty sure on WPC/WPC95, they're new enough that all of them mark the negative terminal.

And they all might not face the same direction on a board.

LTG : )

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