Why does my Uni-T multimeter not measure anything?

[stj]

Re: Why does my Uni-T multimeter not measure anything?

or put an inline fuseholder on the probes wire - fluke sell a probe like that!

[Retro-Hipster]

Re: Why does my Uni-T multimeter not measure anything?

Ah... it's a shame a board that spacious doesn't have A) a 10a fuse and B) HRC fuses...

Ironically, that little gap where the trace was would probably fit one of those tiny 10a hrc axial lead fuses and give your meter an upgrade. Lol (Just heat shrink it well to keep it from the shunt/other terminals.
https://cdn.badcaps-static.com/pdfs/...b127d9a063.pdf

[Retro-Hipster]

Re: Why does my Uni-T multimeter not measure anything?

STJ speaks wise words. lol

Also, I know that this situation is a bit different since you were testing the socket, but if you work commonly with mains stuff I would suggest making a light bulb current limited supply. For the cost of an extension cord, a ceramic light socket and a tungsten/halogen bulb, you can have a socket that will light the bulb up when you make a short while also protecting your equipment/device under test..

[stj]

Re: Why does my Uni-T multimeter not measure anything?

i avoid this by blocking the current jack on my meters and only testing current with a clampmeter.

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

count yourself lucky . i still have 3x £100 meters with lots more damage from doing same thing .
well i say 3 i mean 2 . one got hit with about 20k volts .

I know I am. Lucky because that 315mA 250V fuse blew before any more damage was done. If that fuse hadn't blown, I wouldn't have this mulimeter back up again.

[petehall347]

Re: Why does my Uni-T multimeter not measure anything?

count yourself lucky . i still have 3x £100 meters with lots more damage from doing same thing .
well i say 3 i mean 2 . one got hit with about 20k volts .

[budm]

Re: Why does my Uni-T multimeter not measure anything?

Thanks for the follow-up.

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

As promised, I'm reporting back. The multimeter is back up and running.

Thanks to everyone who contributed!

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

Yes, that trace is gone, so get a thin piece of wire and solder it between the COM and the wire shunt. I suspect the meter will work fine after that.

Thanks! After I do that, I'll report back.

[R_J]

Re: Why does my Uni-T multimeter not measure anything?

Yes, that trace is gone, so get a thin piece of wire and solder it between the COM and the wire shunt. Using a thin piece of wire would be better in case the mistake is made again. I suspect the meter will work fine after that.

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

I'm pretty sure that trace is done-for.

As for the other side, it looks fine.

[R_J]

Re: Why does my Uni-T multimeter not measure anything?

The blown trace could also be on the other side of the board, it is a double side circuit board.

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

Yes, that is exactly where the smoke is. I'll provide that photo tomorrow, as it's 00:29 right now where I live and at 06:20 I have to wake up.

[R_J]

Re: Why does my Uni-T multimeter not measure anything?

If the trace blew it would likely be in this area. Is this where the black smoke is? clean any black soot from the board and provide a clear picture of this area. The COM jack likely connects to the end of shunt wire and also to a trace that connects the COM to the meter common circuit
If you look at the schematic you will see that the COM connects to one ind of R14 (0.01Ω) this is the large wire shunt. It also connects to the comon ends of R17,R29 & R30.

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

I did try that. It showed OL.

As for the blown trace, it's definitely seen some good black smoke. It could be blown, it could be fine. Not sure how to test that without another meter.

[R_J]

Re: Why does my Uni-T multimeter not measure anything?

NO. you should LOOK to see if there IS a blown trace. don't start adding jumper wires.
Have you tried placing the meter in Ω and check what resistance you get when you short the probes together? maybe the meter is working.
The way you had it connected, the large wire shunt was connected across the 10amp and COM jacks. That is what blew the house fuse. it was like connecting a wire across the house outlet. BANG

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

The black lead was in the Common jack. The read lead was in the Ampere (Unfused) jack. I tried to measure DV Voltage with that configuration in an AC 230V outlet.

So, where should I resolder the Common jack? Should I take a wire and solder the Common jack to the large wire? Would that be enough?

What made me think there is a short circuit in the meter is the rise in resistance when I select Ω and then quick drop to OL. Same goes for voltage: see how when I come from resistance it rises and then slowly drops?

[R_J]

Re: Why does my Uni-T multimeter not measure anything?

I thought about that. However, I'm not sure that can cause a short circuit in the multimeter.
I'll try and take a better photo of the burn tomorrow and upload it.

What makes you think there is a "short circuit" in the meter? Your video shows the meter working. When turned to 20MΩ it reads O.L that is normal, When turend to DCVoltage it reads 0.00 Volts which is correct without any "voltage" for it to measure. Have you tried it with the probes connected and placed in the Ω scale, short the probes and see what reading you get?

Like others have said, when you connected the meter in the "10 amp configuration" You would have likely vaporized the trace connecting the probe jacks to the circuit. That large wire bridge is the 10 amp current shunt for the meter You likely blew the trace connecting the common jack to the rest of the meter circuit

Was the black meter lead connected to the com jack when this happened? or was IT plugged into the VΩmA jack.

[antoniu200]

Re: Why does my Uni-T multimeter not measure anything?

From down to up: Common, Fused, Unfused.

Bottom is Common, Top in Unfised.

[budm]

Re: Why does my Uni-T multimeter not measure anything?

If the trace from the probe receptacle is blown then the probe is no longer connected to the meter circuit.
https://www.badcaps.net/forum/attach...1&d=1573479529
You have 3 probe socket, what are each one since we cannot tell which is which because there is pictures of the front side of the meter, also no pictures of the other side of the board that we can see.