I have two identical devices, the Megger MIT525 5 kV Diagnostic Insulation Resistance Tester. One of them present this behavior:

When it is charging connected to the electric network, the device turn on and work, even charge the battery. However when it is unpluged from the network the battery is unable to turn on the equip.

I already interchanged the battery between the devices.

Looking the card I noted this SMT capacitors and I want to know if they are damaged, maybe it could be the cause of the problem.

In the device with the problem: Bad_caps

In the another card they are diferents: enter image description here

I don't have experience in mounting surface. So I want to know if this is an indicator.

How to do I tell if ceramic capacitors are damaged?

Note: If somebody have the technical manual of this device or know how i can get it could be very useful.

  • 2
    \$\begingroup\$ My magic crystal ball is broken, I am afraid you have to measure them yourself \$\endgroup\$
    – PlasmaHH
    Commented Sep 27, 2017 at 14:01
  • 8
    \$\begingroup\$ Those are ceramic capacitors- they don't have liquid inside. What you see in the top photo is flux residue from the solder paste. Doesn't mean they are not bad, but you won't necessarily see anything. \$\endgroup\$ Commented Sep 27, 2017 at 14:04
  • \$\begingroup\$ Sure!. it is a mess you have broken your crystal ball. In fact I already tested it, but over the board, and his values I suppose are influenced by the rest of the board. however, i Will edit the post and add that information. Thank you. \$\endgroup\$ Commented Sep 27, 2017 at 14:05
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    \$\begingroup\$ Note that large ceramic capacitors have a tendency to crack under mechanical stress. It might be those capacitors, but you wouldn't be able to see it. Though it's more likely that one of the transistors fried. \$\endgroup\$ Commented Sep 27, 2017 at 14:18
  • \$\begingroup\$ It seems there is a (10 Ohm?) resistor in the right-down corner on the upper picture and lack of such resistor on the lower one?? Maybe this is a problem? \$\endgroup\$
    – user257712
    Commented Jul 15, 2020 at 15:27

1 Answer 1


I doubt there is anything wrong with those capacitors, at least based on images you provided. If you want to troubleshoot your boards, remove all power from the board first and then take out your multimeter and start probing.

Measure across both sides of the capacitors in resistance (or continuity) mode to see if it is shorted. A short would be an indication that either the capacitor is defective or something else on that line (upstream or downstream) is defective. If you have access to an LCR meter, you could desolder the component and test it directly. However, without schematics, you won't know what the value should be. Still, if you get some wacky reading, like a few pF or it shows high ESR, that may be a sign of problems.

When dealing with an anonymous board like this, I like to check the capacitors, diodes and transistors/FETs. Those are the easiest to check and you may get lucky.

There's not much more we can do unless you can point us to some schematics.


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