Picked the Fluke 87V over the 179 for that 787 APU troubleshooting last week

Took me about 20 minutes deciding at the supply counter in Atlanta which meter to grab. I ended up going with the 87V because of its higher input impedance and better accuracy on those weird bus voltage readings. Turned out I was getting intermittent glitches on pin 14 that the 179 probably would have missed entirely. Anybody else have a go-to meter for certain airframe systems or is it just me?

3 comments

3 Comments

hall.joel24d ago

Man, that is a seriously underrated point about the input impedance on the 87V catching glitches that other meters just smooth over. I've had the same thing happen on some older 727 avionics bays where you'd get phantom signals from bad grounding that a lower impedance meter just completely masks. It's wild how much hidden noise is floating around on those bus lines that a good meter can actually see.

victorh8124d ago

Hall.joel, you ever notice how the 87V also tends to show ghost voltages from capacitive coupling on long cable runs that other gear just misses entirely.

ellioth3724d ago

...and that's exactly why I spent three hours last week chasing a "short" on a control panel that turned out to be my meter being too good at its job. The 87V's high impedance makes it like that friend who sees all the drama nobody else notices, but sometimes I wish it'd just shut up about the ghost voltage on my unplugged speaker wires. My old cheap meter would have just smiled and said "yep, zero volts boss" while I moved on with my life. Now I'm out here second-guessing every floating line and wondering if I'm actually fixing problems or just being haunted by the ghosts of bad wiring past. Makes me wonder though, have you ever had that meter expose a real issue that another tool would have let slide?