(Topic ID: 12283)

What happens when a resistor goes bad?


By sixsixtie

7 years ago



Topic Stats

  • 8 posts
  • 4 Pinsiders participating
  • Latest reply 7 years ago by robertmee
  • No one calls this topic a favorite

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#1 7 years ago

I've been going through my ball accelerator board with a multimeter testing everything. From what I can tell all the transistors are good, the capictors seem fine but I have two wonky 100k resistors. When I measure them they start out at around 50 and they slowly go up to about 65-66 and stop there. I assume that means they're bad. So if those are bad could those two tiny pieces really be the whole reason my supercharger isnt working? They seem so small and in consquential. Should I still be looking deeper?

#2 7 years ago

I would suggest lifting 1 leg and testing them out of circuit.

It's quite possible that something else in the circuit is causing the fluctuations you mention. Or, even the voltage from your meter can throw the reading off.

When a resistor fails, it either goes open (no connection) or the resistance increases. When the resistance increases, it can burn the board, or burn itself up. Modern resistors are 'flameproof', in the past that wasn't always the case!

#3 7 years ago

Interesting. Well I'm at a loss then.

#4 7 years ago

A little more detail on your supercharger problem might help diagnose it. What is/isn't working? Was it working before? The more info posted here, the better chance we have of helping you.

#5 7 years ago

Sorry. I had posted it in another thread. Ill link it.
http://pinside.com/pinball/forum/topic/supercharger-not-registering

#6 7 years ago

It sounds like you're measure with the power ON. Make sure your machine is OFF to measure resistance.

Resistors don't really go bad unless you physically damage them or burn them by applying too much power. In that case, they have a very unique smell. The odor is hard to describe, but you'll know something's not correct.

My thought is that your problem is elsewhere.

#7 7 years ago

Boards out of the machine so definitely not powered.

#8 7 years ago

The value change is due to a capacitor in the circuit....a meter sources a small current through the resistor measures the resultant voltage and through ohms law determines resistance. A capacitor holds additional voltage and discharges it over time. This extra voltage throws off the meters calculation. As john said lift one leg to be sure

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