: Use test points to measure waveforms and voltages, comparing them against the expected values listed in the schematic to find short circuits or failed parts.

Reading a schematic is a skill that requires patience and knowledge of electronics. Here is a step-by-step approach:

HP schematics are rarely released in Gerber (PCB manufacturer) files. They are usually scanned PDFs, sometimes in "B4" size (folded paper).

Whether you are hacking an old OfficeJet for an DIY CNC plotter or resurrecting a LaserJet 4000 from 1998, remember: The paper is just the output. The truth is in the traces.