Author Topic: VC99 handheld multimeter schematic  (Read 3185 times)

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Offline akis

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VC99 handheld multimeter schematic
« on: August 12, 2014, 07:09:04 pm »
I noticed my handheld multimeter is a bit off when it comes to DC voltage measurement. I have opened it and it has a dozen trimmers. I do not know which one is responsible for the DC voltage measurement, so I am not touching anything. Doing a search on the net has not produced a schematic or a "calibration procedure".

I need the schematic or ideas how to fix it. I do not want to hear "throw this crap out and buy a proper multimeter".
 

Offline omgfire

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Offline johansen

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Re: VC99 handheld multimeter schematic
« Reply #2 on: August 13, 2014, 07:23:16 am »
i should know this off the top of my head, because i just did this with mine. i think its either number 4,5 or 6, i can't recall, i do recall it was a rather wide range, it took a bit of effort to get it within a millivolt from my 1.0186volt weston cell.
 

Offline akis

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Re: VC99 handheld multimeter schematic
« Reply #3 on: August 13, 2014, 07:32:32 am »
Thanks for the schematic and info, will read through the PDF now to see which trimmer it is.

Edit: looking at the suggested schematic it appears VR1 adjusts the ref voltage so I used just that to set the true DC voltage. Hopefully it has not affected anything else.
« Last Edit: August 13, 2014, 01:48:34 pm by akis »
 


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