LCR meter BSIDE ESR02 Pro problem

[Filippo52]

I wanted to ask for help on this forum which I believe is one of the few places I could get it.
Last night my meter stopped working properly but it doesn't look totally broken. It does strange things that I try to describe with the help of photos.

It turns on regularly but without putting anything to measure instead of giving the message after a few seconds
"No, unknown, or damaged part"
waits for 15 seconds and then gives the message you see in the picture for another 25 seconds. And then the screen goes white at the lowest brightness.
If you put a component to measure nothing changes.
You can access the menu but it doesn't seem to work properly. For example, if you try to do the "Selftest" the message "Short Probes!" stays on for a while and then returns to the menu.
I checked and the apparatus absorbs over 100mA against the approximately 20mA that a functioning one absorbs.
I'm afraid something happened but I don't have the schematic and I don't know where to put my hands,
Does anyone have the schematic? or can you give advice?
Thank you

[madires]

Most likely two MCU pins are toasted (charged cap?). You can replace the MCU and program one of the two OSHW firmwares.

[AkibUddin]

I wanted to ask for help on this forum which I believe is one of the few places I could get it.
Last night my meter stopped working properly but it doesn't look totally broken. It does strange things that I try to describe with the help of photos.

It turns on regularly but without putting anything to measure instead of giving the message after a few seconds
"No, unknown, or damaged part"
waits for 15 seconds and then gives the message you see in the picture for another 25 seconds. And then the screen goes white at the lowest brightness.
If you put a component to measure nothing changes.
You can access the menu but it doesn't seem to work properly. For example, if you try to do the "Selftest" the message "Short Probes!" stays on for a while and then returns to the menu.
I checked and the apparatus absorbs over 100mA against the approximately 20mA that a functioning one absorbs.
I'm afraid something happened but I don't have the schematic and I don't know where to put my hands,
Does anyone have the schematic? or can you give advice?
Thank you

You want to took risk about it  Be sure about battery supply socket (adapter socket polarity) ok or smd pad not shorted !

[Filippo52]

thanks for the answer but when it happened I was trying components that had been in the drawer for months, and therefore there could not be a charged cap.

[Filippo52]

The polarity of the power supply is OK.
But if I measure, as you suggested, with a tester the resistance between any two of pins 1, 2 and 3 in a good and working ESR02  I measure 2-3 Mohm while in the broken one I find 20-30K.
The measurements change a lot using different meters and ranges and even more with another instrument like an LCR; but anyway in the faulty device the resistance is much lower.
I have cleaned the PD more than once, if I had the schematic I would see if there are capacitors in the paths:
Anyway, thanks for the clear and sensible answer

[Filippo52]

Referring to your
" or smd pad not shorted !"
I tried to cut the tracks that connect the ATMega328 outputs to 1, 2 and 3 of the pad as well.
Unfortunately, the resistance value measured between the ATMega328's pins remained the same, while that of the measurement points 1,2 e 3 both on the pad and on the main connectors decreased significantly, becoming similar to that of the working Bside ESR02.
I'm afraid at this point the ATMega328 is damaged even though I didn't use charged capacitors. I fear it could be damaged even if during the measurement the capacitor is not firmly in its seat and makes jumping contacts

[madires]

Bad contacts won't kill the ATmega, but voltages above 5V. There's a protection relay hardware option which might help, or a simple modification with an SRV05-4 and a TVS.

[Filippo52]

Thanks for your kind reply. But I have used capacitors that have been in the drawer for months and therefore definitely discharged.
The only mistake I may have made is in positioning them for their size. Sometimes the capacitor has slipped out of my hands and I've put it back in without discharging it; but they could only have the charge that the ESR02 gave them.
I may have touched a capacitor lead with my hands and maybe I had a static charge in my hands.
I'm not very practical and I didn't understand the abbreviations that he gave me as a simple modification; What are?

Thanks again

[madires]

You'll find them in Karl-Heinz's documentation (https://github.com/kubi48/TransistorTester-documentation).

[precaud]

The same thing happened with mine. After 1 month it powered up to a white screen. I never used it to test capacitors, just transistors/diodes. Replaced it with one where the ATmega chip was socketed.

[Filippo52]

After some time, re-examining the scheme, I can make another hypothesis.
The measurement input lines go directly to the CPU without any type of protection.
Even if capacities with residual charge are not measured, it is sufficient for the operator to hold the terminals, for example of a diode, with his hands and have a residual electrostatic charge on him to kill the ATmega, or damage it so that then those strange results