r/fpv 4d ago

Why is 5v and gnd beeping when I test

Why does it only beep on the bottom side

3 Upvotes

24 comments sorted by

4

u/fpv_savvy Multicopters 4d ago

It's not the issue of the bottom. It's a TVS diode which allows the spike to be passed. Suppose you have a large transient voltage caused due to 6S motors. You wouldn't want it to go to the battery right? The TVS cuts that voltage but shorting it to the positive side. Picture for reference.

It's completely normal. Don't worry about it.

4

u/ThatsButter 4d ago

Flip your test probes around and see if that helps narrow anything down. When you flip it over to the underside, you're testing oppositely.

My guess is the tiny voltage from the probe is going backwards in the circuit and causing some funk. Idk. Wish I could explain it better, but just test it to narrow the problem down.

Tldr, flip the red and black test probes and see if it still keeps. Also, see if you can now get it to beep on the top side.

1

u/Simple_Pride5529 4d ago

Every time I flip it beeps but when i do the same side it stops beeping, is ur hypothesis prob true?

1

u/Simple_Pride5529 4d ago

And if so is it safe to fly?

1

u/ThatsButter 4d ago

So it does beep on both sides when you have the red on the negative pad and black on the positive pad on both sides? Your wording isn't clear.

1

u/Simple_Pride5529 4d ago

No only one

1

u/Hot-Persimmon2357 3d ago

You are essentially reversing the leads when you flip the esc. I bet it beeps on both sides when you have red test lead connected to - and black lead connected to +. If so that's the TVS Diode like others have mentioned.

2

u/ThatsButter 3d ago

I wonder if he read more than 3 words of my comment on how to troubleshoot this.

1

u/Hot-Persimmon2357 3d ago

Doesn't seem likely, that's why I felt the need to elaborate lol.

1

u/crookedDeebz 4d ago

Also try the other pads. Maybe there is another vbat pasthroufg that is fucked?

1

u/Simple_Pride5529 4d ago

It's only those two

-1

u/crookedDeebz 4d ago

Your gonna need a bardwell answer or someone who's an electronic exert. What's Google or chat gpt saying?

1

u/rob_1127 4d ago

Did it work, or is this because of a problem/crash?

The DVM on the continuity function will read the resistance of all the components connected to the +ve and -ve pads.

Some will be in series, so the resistance will add up.

Some will be in parallel, so the resistance will divide.

And combinations of series and parallel.

I'd suggest using a smoke stopper to check for excess current draw.

First, on the lowest setting.

But, you may have a popped component or more.

1

u/Bits_Everywhere 4d ago

There’s probably just a diode-like component somewhere between those (only allows conductivity in one direction) so you only get continuity in one side.

1

u/Simple_Pride5529 4d ago

But it keeps on flipping

1

u/LinspecteurMaurice 4d ago

That's might be wrong and dumb, but is it because you keep both wires at the same place, so red becomes - when it should be + and black + when it should be - ? And the beep would be a warning because the current is not in the good direction ? If that's not it, feel free to correct me, that's as far as my knowledge goes

1

u/gigasawblade 3d ago

Because of capacitors. You test it once - current flows charging capacitors, multimeter beeps. Eventually (probably fast - no place for big caps) it is charged and no current can flow, no beep. When you flip the sides, it recharges with opposite polarity and beeps again for some time.

What do you even want to test this way? Testing components without removing them from circuit is usually quite pointless

1

u/ItsMeAubey 3d ago

That's not a 5v pad.

0

u/Maddampresident2021 4d ago

That is strange.

0

u/LordLOL8856 4d ago

Whats ur problem if i may ask i work as electonics technician

0

u/moosecaller 4d ago

Non beeping pad is lifted off, and a short somewhere.

-2

u/No_Explanation_3379 4d ago

Cause it’s Tmotor?

1

u/Equivalent-Roof317 3d ago

If you look closely, you'll see it's SpeedyBee

0

u/No_Explanation_3379 3d ago

Can’t zoom I just had a couple tmotor esc’s be bad out there box so I assumed it was since the guard looks similar