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 Post subject: Lab-Volt Fet multimeters
PostPosted: May Mon 17, 2021 1:25 am 
New Member

Joined: Jun Fri 08, 2018 4:23 am
Posts: 16
Location: Queretaro, Mexico.
hello again, i have an old Lab-volt Fet multimeter, i hope somebody can help me with the manual or schematic or the calibration procedure? mine is the green one, but i discover another model that looks apparently the same without the current section.

any help or ideas will be really appreciated


best regards

Pio


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 Post subject: Re: Lab-Volt Fet multimeters
PostPosted: May Mon 17, 2021 7:24 am 
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Joined: Jun Sat 15, 2019 7:43 pm
Posts: 1335
Lab Volt equipment was sold to schools as training equipment, the schematics were never supplied. If you had a problem they were sent back to the factory for repair.

DM


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 Post subject: Re: Lab-Volt Fet multimeters
PostPosted: May Mon 17, 2021 7:51 pm 
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Joined: Mar Sat 03, 2007 12:53 am
Posts: 871
Sometimes the calibration pots are marked on the PC board (e.g., zero adj, .5 VDC adj., etc.). Providing this information would make it possible for members to suggest a calibration procedure that would work. If this is not the case, it's possible to trace the circuitry and draw a schematic (or partial schematic) of the circuitry which would make it possible for members to suggest a calibration procedure that would work. If drawing a schematic is difficult to accomplish, for each calibration pot, it's possible to shunt the wiper and a terminal that is not connected to the wiper of the pot with a resistor that is 10 times the value of the pot and determine which functions and ranges are affected by the shunt. This information would enable members to suggest a calibration procedure. Minimally, I would expect there to be a zero adj., .5 VDC adj. and an AC adj. pot. Some meters may have more pots (e.g., both a .5 VDC and 1.5 VDC adj. pots).


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 Post subject: Re: Lab-Volt Fet multimeters
PostPosted: May Mon 17, 2021 9:07 pm 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 4846
Location: Melbourne, Florida
I identify unmarked cal pots by feeding in a known voltage and then tweaking pots in turn until I find the one that has an effect on the meter reading. Ones that don't are returned to their initial positions until they are also identified.

RRM


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 Post subject: Re: Lab-Volt Fet multimeters
PostPosted: May Tue 18, 2021 1:31 am 
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Joined: May Sun 10, 2020 2:55 pm
Posts: 1553
Location: SW, MI
nice looking meters.. can't be referenced against know manufacturer products like many other ed items? i.e. my Eci scope was made by iwatsu and match model. never heard of lab-volt

_________________
only the dead fish go with the flow


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 Post subject: Re: Lab-Volt Fet multimeters
PostPosted: May Tue 18, 2021 4:46 am 
Member

Joined: Jun Sat 09, 2007 8:14 am
Posts: 4846
Location: Melbourne, Florida
Mr. Google says this is the outfit that makes Lab-Volt equipment. He knows about almost everything.

https://labvolt.festo.com/solutions/2_e ... nstruments

A letter to them might get some data. I've had better luck with actual letters instead of email when looking for old product information.

RRM


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 Post subject: Re: Lab-Volt Fet multimeters
PostPosted: May Sun 23, 2021 6:17 am 
New Member

Joined: Jun Fri 08, 2018 4:23 am
Posts: 16
Location: Queretaro, Mexico.
thank you for the input, the wiring scheme in those is difficult to trace because is tied with knots and the circuit is covered with varnish.

here are some pictures

best regards


Pio


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File comment: that is the most i can take apart the pcb due the wiring tied and knots.
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File comment: that is the most i can take apart the pcb due the wiring tied and knots.
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photo_2021-05-23_00-08-39.jpg [ 475.47 KiB | Viewed 230 times ]
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File comment: the ammmeters section is separated and no need ac power.
photo_2021-05-23_00-08-53.jpg
photo_2021-05-23_00-08-53.jpg [ 846.54 KiB | Viewed 230 times ]
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