Circuit Card Academy
← ToolkitUse Print / Save-as-PDF · Letter

Bench Checklists

ESD/FOD · power-on sequence · first five minutes

Circuit Card Academy

A · ESD / FOD pre-work (before the tote is opened)

Wrist strap on, connected, and tested today
Dissipative mat & common-point ground verified
ESD smock on; no synthetic / charge generators
Common plastics (cups, tape, foam) clear of area
Board handled by edges, in shielded bag until use
Grounded iron; tools accounted for (FOD control)
Work area clear of debris & mixed hardware
Calibrated DMM / scope (check cal sticker date)

B · First five minutes (before any powered measurement)

  1. Read the work order / failure ticket fully — what failed, measured vs. limit, hard or intermittent, history.
  2. Get the schematic, BOM (this revision), assembly drawing, and test spec. Identify “known good.”
  3. Inspect under magnification: burns, bulged caps, cracked MLCC/tantalum, cold/cracked joints, bent connector pins, FOD, coating damage, prior rework, missing/wrong/reversed parts.
  4. Power-off rail checks: fuses by continuity; each rail-to-ground signature (note any dead short before powering in).
  5. Write down what you expect at each node before you probe.

C · Power-on sequence (current-limited supply)

  1. Set expected input voltage; set current limit just above expected draw.
  2. Apply power. Read supply current first — far too high = short / latch-up; near zero = not starting.
  3. Verify every rail at its test point in dependency order (e.g. 28 V → 5 V → 3.3 V → core). Present, in tolerance, clean on the scope.
  4. A missing rail: check that regulator’s input first. A sagging rail: regulator weak vs. load heavy — lift the load to decide.
  5. Digital: confirm clock running → reset releases → bus activity (the power → clock → reset → activity hierarchy).

D · Before you close the job

Root cause identified (not just the symptom)
Repair per IPC-7711/7721; correct part & orientation
Cleaned; conformal coat restored; full ATP passes
Traveler complete with measured values & lot #s

Generic best-practice checklists for training. Defer to your facility’s controlled procedures and ESD program (ANSI/ESD S20.20) for flight hardware.