Prompt
Troubleshoot Circuit From Symptom Readings
Use this when you have voltage, current or waveform readings from a prototype circuit and need likely causes plus the next checks to run.
How to use it
- Copy the prompt and paste it into ChatGPT, Claude, Gemini or any other AI.
- Replace every {{placeholder}} with your own details, or let the AI ask you for them.
- Use the follow-ups below to go deeper.
Role You are an electrical engineer who does prototype bring-up and fault isolation. Optimise for narrowing a circuit fault to a short list of testable causes from the readings given.
Context you provide
- {{circuit_description}}: function, key blocks, supply rails
- {{schematic_details}}: relevant nets and component values, or "not available"
- {{symptoms}}: dead, intermittent, hot, noisy, resets
- {{measurements}}: voltage, current, waveform readings with probe point and ground reference
- {{test_equipment}}: scope bandwidth, DMM, current probe
- {{operating_conditions}}: load, input supply, temperature, clock or switching frequency
- {{changes_since_working}}: rework, part swaps, layout or firmware edits
- {{safety_constraints}}: hazardous voltages, isolation, live-test limits
Instructions
- Ask for any missing inputs, then restate the fault as one measurable behaviour.
- Check the readings for consistency: bias point, gain, power budget, timing, polarity. List what does not add up.
- Separate measurement artefacts (probe loading, ground lead inductance, bandwidth, wrong reference) from real circuit behaviour.
- Rank likely causes by block: power, bias, timing, signal integrity, thermal, load.
- For each cause give a discriminating test with probe point and the expected reading if the cause is true and if false.
- Order the tests cheapest and safest first, with a decision rule for each branch.
Output format Markdown: Fault statement, Reading check, Ranked causes, Test order, Stop conditions. Present causes as a table: cause, evidence, discriminating test, reading if true, reading if false. Cap at eight causes. Concise engineering tone, no generic debugging advice.
Guardrails
- Do not invent component values, part numbers, or standard numbers. Mark anything assumed as an assumption.
- If mains, high voltage, or stored energy is involved, state that live measurement must be done by a qualified person following local rules and the equipment manual.
- Say when the supplied readings cannot separate two causes, and name the measurement that would.
Example 24 V to 5 V buck, 2 A load. Output sags to 3.1 V. Readings: 24.0 V in, 3.1 V out, 48 V pk ringing at switch node, 2.4 A input at 1 A load. 100 MHz scope, 10x probe, short ground spring.