Multimeter not working after high voltage incident

I was using maxcom mx 620 multimeter to measure the output of a high voltage power supply (I'm an undergraduate mechanical engineering student and needed the power supply for a project). since the multimeter has a maximum of 1000 volts DC, I used two resistances in series and measured around one of them to reduce the voltage to a few hundred volts. This worked until one of the resistances some how failed, and the voltage went around it. The multimeter turned itself off. I turned the dial to the off position and back. and the screen had all the "setting indicators" displayed at the same time, and keeps giving a reading that increases until it reaches "OL", (which is usually given when the input exceeds the maximum allowed), without the test leads actually touching anything.

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I disassembled the multimeter and found that a fuse inside had blown, but after changing it, the problem persisted. Is there any way to fix it?

Thanks in advance

Update (07/03/2017)

To my eyes, nothing is amiss. There are no burn marks, no inflated capacitors, no cracked components. Unfortunately, I have nothing to test the diodes with, as I've seen failed diodes that have no visible marks on their outside.

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Answered! View the answer I have this problem too

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2 Answers

Chosen Solution

open up the multimeter check for any possible burnt electronics components inside,

e.g. smd resistors, transistors, etc.

it would be great if you can share some pictures of the circuit internals.

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Comments:

you need another multimeter to do some testing, maybe start with some .... like diodes (D*).... transistors (Q*)

you can try ordering and replacing the op amp and see how for the ST TL062CN, KA324 first

one of the components which i cannot see properly which is the14 pin dip on the top of R50, near to one 8 Pin ST TL062CN op amp

if the components exceed your multimeter cost, i would advice to get a new one.

for later if the multimeter has been fixed, it would be great if you can replace the electrolytic capacitor too, let me know the values of it.

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The 14 pin dip is "GS 9432 GD4070B"

I got my hand on a multimeter and checked on all 13 diodes and they were ok

The values of the capacitors are:

C8 50v 4.7uF

C14 16v 100uF

C17 6v 10uF

C7 50v 0.47uF

I'm going to check on the transistors next then the amps

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just some sharing which might help...

https://www.youtube.com/watch?v=PJBbd9rX...

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You've probably damaged the DAC ...it could be fixed but you'd then need to calibrate it

buy a new one much easier

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