Power Amplifier · Yamaha · CR-640
Diagnosis: Blows Fuse
The unit blows a fuse or trips a breaker.
Safe first checks
- Unplug the unit immediately.
- Use only the exact fuse type and rating specified by the manufacturer.
- Never install a larger fuse, foil, or any bypass.
- Do not power it on repeatedly; repeated attempts can cause further damage.
Bench Technician Steps
This is the model of work a qualified electronics technician follows using the exact service manual and suitable test equipment. It is not a do-it-yourself instruction to work on energized equipment.
- With the unit deenergized, document the original specified fuse and inspect the power supply, rectifier, output stage, and wiring for evidence of a short or heat damage.
- Use appropriate deenergized semiconductor and resistance checks to look for shorted rectifier diodes, output devices, or power-rail faults; compare matched channels where the circuit allows it.
- Before normal power is applied again, use a controlled current-limited start-up method and the exact service documentation to isolate abnormal current draw.
Guided follow-up
Ask the Repair Assistant
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