Use when: Creating a prioritized, step-by-step multimeter troubleshooting plan for a PCB or circuit based on fault hypotheses. Generates actionable measurement instructions with expected values and safety notes. Messplan, Multimeter, Messanleitung, Prüfplan, Testplan, Spannungsmessung, Widerstandsmessung, Durchgangsprüfung.
<skill_purpose> Translates fault hypotheses into a concrete, ordered measurement sequence executable with a standard handheld multimeter. Maximizes diagnostic information per step and explicitly handles safety constraints. </skill_purpose>
<input> - Prioritized fault hypotheses (from `fault_hypothesis_engine` or equivalent) - Functional block map with critical nodes (from `functional_block_reconstruction` or equivalent) - Known supply voltage and basic circuit topology - Optional: Any measurements already performed (to avoid redundancy) </input> <instructions> 1. Select measurements that provide the highest diagnostic value for confirming or refuting the top-priority hypotheses first. 2. Name measurement points unambiguously (e.g., "J1 pin 1 positive terminal", "collector of Q1", "U2 pin 3 VCC"). 3. Specify expected values or expected behavior — not just "check if voltage is present". 4. Explain what a deviation from the expected value means in terms of specific fault hypotheses. 5. Prioritize load-condition voltage measurements when the symptom is load-dependent. 6. Use differential comparisons (two-point measurements) to localize faults — absolute values alone are less diagnostic. </instructions><output_format>
Create or update analysis/05_multimeter_test_plan.md (or the path specified by the user).
Per measurement, use this mandatory table format:
Measurement [N]: [Short descriptive goal]
<rules> - Resistance, continuity, and diode test measurements: specify device state as DE-ENERGIZED — always state this explicitly. - Voltage measurements under load take priority when the symptom is load-dependent — schedule these as Measurement 1 or 2. - Use differential measurements (compare two points in the same current path) to localize the fault segment, not just detect its presence. - Recommend only measurements feasible with a standard handheld multimeter — no oscilloscope or specialized equipment assumed. </rules>| Field | Content |
|---|---|
| Objective | [Which hypothesis does this confirm or refute?] |
| Test points | [Exact probe placement: red probe at X, black probe at Y] |
| Meter mode | [DC Voltage / AC Voltage / Resistance / Continuity / Diode] |
| Device state | [DE-ENERGIZED or ENERGIZED — specify load condition if relevant] |
| Expected result | [Nominal value or expected behavior, e.g., "3.7V ± 0.2V"] |
| Deviation interpretation | [What does a low / high / zero / infinite reading indicate?] |
| Safety note | [Short-circuit risk, required precautions, or "None"] |
Example (adapt to the actual circuit — do not copy verbatim):
Measurement 1: Battery terminal voltage vs. circuit VCC under load
| Field | Content |
|---|---|
| Objective | Detect contact resistance between cell and circuit input — confirms or refutes cold solder / connector fault |
| Test points | M1: red=cell(+) terminal, black=cell(-) terminal / M2: red=VCC pad on PCB, black=GND pad |
| Meter mode | DC Voltage |
| Device state | ENERGIZED, under normal operating load (motor running or equivalent) |
| Expected result | M1 ≈ M2 (difference < 0.1V). Difference > 0.3V indicates resistive fault in the path |
| Deviation interpretation | Drop localized between J1 pins → cold solder or oxidized contact. Drop across trace → PCB trace damage |
| Safety note | Keep probes clear of adjacent pads — short-circuit risk at close-pitch connectors |
Measurement 2: Continuity check across J1 solder joints
| Field | Content |
|---|---|
| Objective | Verify mechanical integrity of battery connector solder joints |
| Test points | Red probe at J1 pin 1 pad (PCB side), black probe at J1 pin 1 lead (component side) |
| Meter mode | Continuity (buzzer) or Resistance |
| Device state | DE-ENERGIZED — remove battery before measuring |
| Expected result | Buzzer sounds immediately / resistance < 0.5 Ω |
| Deviation interpretation | No buzzer or R > 1 Ω → cold solder joint or cracked joint confirmed |
| Safety note | Measure only with power removed — resistance mode requires de-energized circuit |
| </output_format> |