repairing the DT830B digital multimeter

JimB said:

Kavish,
Post your question ONCE.
Not three times.

JimB

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absf said:

Take a good & clear picture and mark the resistors which were sparked .....

Allen

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JimB said:

Kavish,
Post your question ONCE.
Not three times.

JimB

Click to expand...

absf said:

I believe the 2 blown resistors are R7 and R8 in the schematic attached.

View attachment 91268

I guess you must have measured high voltage using the mA current range OR you are measuring voltage using the 10A and COM inputs. That's why the fuse is blown off instantly. In the fuse position you can solder a piece of fine copper wire e.g. 32 SWG. Put back the battery and see if the LCD still able to display anything. If not, I guess the 7106 chip is toasted and it's not worth your effort repairing it.

If the LCD does show something then test it with the DC and Ohm range and see if it works correctly. Only then replace R17 and R18, probably 1Ω and 9Ω resistors.

Allen

Click to expand...

absf said:

I believe the 2 blown resistors are R7 and R8 in the schematic attached.

View attachment 91268

I guess you must have measured high voltage using the mA current range OR you are measuring voltage using the 10A and COM inputs. That's why the fuse is blown off instantly. In the fuse position you can solder a piece of fine copper wire e.g. 32 SWG. Put back the battery and see if the LCD still able to display anything. If not, I guess the 7106 chip is toasted and it's not worth your effort repairing it.

If the LCD does show something then test it with the DC and Ohm range and see if it works correctly. Only then replace R17 and R18, probably 1Ω and 9Ω resistors.

Allen

Click to expand...

when i using multimeter a kind of spark have been seen inside.

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JimB said:

What were you doing when the spark was seen inside?

By best guess is that your meter is now scrap, beyond economical repair, and should be replaced by a new one which works.

JimB

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