NavTek Value VMV-1 Vacuum Gauge Teardown

VMV-1 Vacuum Gauge
VMV-1 Vacuum Gauge

Time for another tool teardown! Here’s a VMV-1 Vacuum gauge, for refrigeration system service use. This unit will measure in Pa, millibar, mmHg & InHg, displaying it’s reading on a nice backlit LCD. Power is provided by a trio of AA cells.

1/4" SAE Flare Fitting
1/4″ SAE Flare Fitting

The brass fitting at the end of the unit holds the 1/4″ SAE flare port for attaching to the system under service.

Main PCB
Main PCB

Removing 4 screws on the back allows the casing to come apart. Some quite simple circuitry in this unit. There’s the usual STM8 microcontroller which is very popular with the Chinese manufacturers, a beeper, along with some passives & support components. The vacuum sensor is on the left.

Vacuum Sensor
Vacuum Sensor

Here’s the brass block that houses the vacuum sensor itself. According to the manufacturer, this is a Pirani sensor, but I have no way to confirm without destruction of the unit. There’s a built in temperature sensor in the brass block, and the front end of the circuitry is (assuming my decoding of the SOT-23 component markings is correct!) taken care of by a TS507 precision R2R Op-Amp. There’s also a TSX561 micropower wide-bandwidth Op-Amp, along with an LD39020 LDO linear regulator for power supply functions.

4 thoughts on “NavTek Value VMV-1 Vacuum Gauge Teardown

      1. Kyaw lwin thu says:

        Why does the navtek vacuum gauge show only 0.75?

        Reply
  1. venkatesan says:

    hi guys we have NAVTEK micron guage BUt once switch on itwas shows error message how to rectify this please

    Reply

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