Posted on 4 Comments

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. Why display only 0.75?

    1. Hi Kyaw,

      Not sure I understand what you mean. Can you be more specific?

      1. Why does the navtek vacuum gauge show only 0.75?

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

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