Teardown & Repair of a Fluke 744 Documenting Process Calibrator (Parts 1 & 2)

In this episode Shahriar attempts to repair a Fluke Documenting Process Calibrator. The device does not power on with neither a battery nor an external power supply. Although the schematic of this particular instrument is not available, an older model schematic shares many of the design aspects. After close examination of the circuit and various testing of power supply sub-circuit, real-time clock and main processor, it becomes clear that the problem is with a corrupt firmware. The repair is put on hold until a firmware upload method is determined.

After some help from the community, a new firmware has been found and can be uploaded into the instrument. By forcing the processor into a bootloader mode, the firmware update can happen even if the original firmware is corrupted. After the firmware fix, the instrument is tested for various functionality include DC/AC/I/Resistance calibration and measurement modes.

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