Philips PM6654 intake and display repair


30 May 2023
Philips PM6654 intake and display repair
The initial intake of the Philips PM6654 went pretty smoothly. Most features are tested including frequency, pulse width, rise and fall time and phase. Particularly rise and fall time as well as phase measurements seem quite sensitive and it is difficult to produce good readings. This aligns with the user and service manuals were these measurements are averaged and require substantial dead time between measurements.

All operations do seem within specification so no adjustments are needed. However, the display does show weaknesses. This included the first 3/4 decimals not lighting up, the second function column not lighting up and the display of Hz / Seconds / Volts being intermittent.

Upon investigation the cause was found to be a tiny piece of metal that was hanging from a spider web. This spider web was in close proximity to pins on the rear shorting them together intermittently. Removing this piece of metal as well as some general debris removal resolved the issue entirely.