Can wrong polarity in MM destroy components?

[Sraros]

On a TV that got stuck at the logo, I opened to check the voltages from the PSU to the main.

Instead of putting the black probe to the ground I put the red one and just didn't bother to get negative voltages. At some point as I was checking through the pins the backlights went off for a sec and then on again. I screwed the TV back together to check it thoroughly another time, plugged it in one more time and the picture was gone.. only backlights.

Can it be that using the probes inverted when measuing voltages with the MM can damage the panel or in general el.components?
I didn't short any pins with the black probe checking the pins for sure.

[dick_barton]

Re: Can wrong polarity in MM destroy components?

Reversing the meter probes when measuring voltage results in reverse polarity of the reading displayed on the multimeter. That is for example, 5.0V becomes -5.0V and does not cause a problem.
The possibility that a probe may have shorted two pins together (slipped) when taking a measurement could result in damage.

[petehall347]

Re: Can wrong polarity in MM destroy components?

only way damage might be caused by the meter is by having meter leads set to amps . i have blown a few meters doing this as it happens .

[Sraros]

Re: Can wrong polarity in MM destroy components?

Hm what about continuity mode? I am trying to remember if I have left the MM by accident in continuity when I measured it in off state and then powered the tv but forgot to change to voltage setting. For sure I didn't put in anytime the MM in resistance setting.

[budm]

Re: Can wrong polarity in MM destroy components?

It will depend on what the break down Voltage in the meter mode is. What section of the TV and the connector were you probing?
It can also be co-incident too.

[Sraros]

Re: Can wrong polarity in MM destroy components?

I was checking the voltages from the PSU to the main and it damaged the panel board. The TV doesn't have a T-con, it goes directly from main to the control board. The input voltage of the panel is 12V

[eccerr0r]

Re: Can wrong polarity in MM destroy components?

Most modern DMMs limit current to milliamps when in resistance/diode check mode, and usually are not enough to damage circuitry even if the meter was set to these modes. This is not the case for old analog multimeters where in Rx1 mode it would happily send 100+ milliamps which can destroy semiconductors.

However this is assuming you're probing when off. When probing when on, you have a different problem: if you probe a high impedance circuit with resistance/continuity/diode check, you can trigger that circuit to turn on when it wasn't supposed to, and damage it that way. And of course having the meter in current mode when you're really checking for voltage causes dead shorts, also potentially causing damage to the device under test.

That being said, the usual method for destroying something with multimeters is shorting adjacent pins with a slipped probe, regardless if it's a digital or analog or VTVM.

[Sraros]

Re: Can wrong polarity in MM destroy components?

A little late but thanks for the analytical reply.
For sure since then I am much more careful when checking voltages and diode mode when devices are off. I am inclining that the damage back then was done when I measured in diode mode while the tv was still on…

[angelos]

Re: Can wrong polarity in MM destroy components?

Ox gamoto