jyoon

Sorry, but this is somewhat general question. I'm testing an ignition control module/power transister with a Flukes 78 Multimeter. In the haynse manual (this is actually for a 93 nissan sentra) it says to check the resistence between these two terminals and if it's infinity (little infinity sign) the item is ok. Well on the flukes multimeter, there isn't an infinity symbol that lights up, when i hit the two terminals, the display doesn't change at all. My question is, does this mean it's "infinity" and ok? Or what should "infinity" display on a multimeter? thanks.

Charlotte944

When testing a transistor with an ohm meter you check each junction both ways. In other words, tested one way a good junction will read infinity, or open, and the other way you should see some resistance.

You need to take 6 measurements. Emitter to base front to back, emitter to collector front to back, and base to collector front to back.

However, you need to be mindfull of parallel paths for current flow. Things like bias and load resistors can throw the readings off.

As for the meter display not changing, all digital VOMs default to 1 to indicate the meter is reading a value outside of the currently selected range. Try shorting the meter leads together. You sould get zero ohms.

jyoon

ok, so does infinity = open circuit? i guess that's the question.

Chris_924s

Yes. Zero ohms is closed.