Megger MIT420 (400 Series) Insulation Resistance Meter

[ibd1977]

Hello

I currently have an Megger MIT420 displaying an E45 Error Code.   Does anyone know what the code means and have any schematics for troubleshooting and repair?

The unit appears to have an internal short when using insulation resistance mode.   Upon opening & inspecting, there is definitely a burnt electronics smell present and what looks like a metal oxide varistor has burnt out.   See attached photos.

I would like to attempt a repair but I cannot identify the part that has failed.

Any feedback would be appreciated.

Thank you.

[geggi1]

From what I can see at your first picture my suggestion is that you try to remove the varistor on the input and see if the error code is gone.
You could also try to contact Megger directly about what the error code is representing.
I live in Norway and the Norwegian Megger.no is very helpfull if you contact them.

[ibd1977]

Yeah tried Megger but they are only interested in selling us a new meter and not parts to repair.   Typical anti-repair business model.

So yes to your question, I have removed both MOV's as they both appeared damaged and it cleared the issue.  The meter appears to be working properly but now without any circuit protection. 

These are the components I have identified from this meter and other meters we have in our facility.

Insulation Resistance Side
Mfr. No: V1000LA160BP
Mfr.: Littelfuse
P/N P1000L16

Multimeter Side
Mfr. No: B72220S0110K101
Mfr.: EPCOS / TDK
P/N S20K11

Any suggestions where I can buy 1 of each which could be posted in the mail or locally sourced in Adelaide, Australia?

[Ice-Tea]

Both Digikey and Mouser have stock and ship to Australia...

[lowimpedance]

Also look closer at the resistor below the MOV, it looks to have been stressed too although hard to tell from the pic.

[ibd1977]

Measuring ~4.9 Kohms but the colour bands have discoloured so I can't tell what value its meant to be.