# Troubleshooting School 14 symptom lessons (10 real, 4 explicitly PENDING to show where real diagnostic knowledge ends), built on `` . 4 further PENDING topics (Software installation issues, Dealer-reported issue log, Service/RMA issue log, Speaker/Subwoofer-specific troubleshooting) are catalogued in the source guide but not repeated as standalone lessons here to keep this course to the requested 14. ### Lesson 1: No Power FP-8A/FP-12A: check power connection is properly connected; check connection method is correct. FX-4: check all connections and mechanical contact; check the fuse. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 2: No Sound FP-8A/FP-12A: check mute mode is not activated; check correct input channel is selected. FX-4: check speaker cable/plug connections. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 3: No Sound + Red LED Protection lit FX-4: plus/minus speaker wires shorted — eliminate the short. Or amp overloaded (2Ω speaker in stereo mode, 4Ω in bridge/tri-mode) — turn gain to 'min'. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 4: Poor Sound Quality / Distortion FX-4: speakers overloaded — turn down volume and check. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 5: No Stereo Sound + Weak Bass FX-4: speaker (+)/ cables mixed up, unit wired out of phase. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 6: USB connection not available FP-8A/FP-12A: check USB cable inserted correctly; check Windows Device Manager for a 'HID-compliant device' entry. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 7: Ground Loop / Humming Noise FX-4: use thicker ground cables or add further ground cables to the chassis. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 8: Electronic / Ignition Noise FX-4: add interference-suppression choke to power wiring; keep signal/speaker/power cables physically separated. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 9: Fuse Blown FX-4: check power connection, replace with specified amperage fuse. If it blows again, consult dealer — possible internal malfunction. Never bridge the fuse. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 10: Overheating / Protection Mode FX-4: protection circuit activates on overheating or short-circuited speaker terminals. Do not test by covering the heatsink. **Diagnostic exercise:** walk a customer through this symptom step by step, citing only the real manual text above. ### Lesson 11: Turn-on Pop PENDING VERIFICATION — no local document covers this. Do not improvise a diagnostic script for this symptom. ### Lesson 12: Optical input troubleshooting PENDING VERIFICATION — no local document covers this. Do not improvise a diagnostic script for this symptom. ### Lesson 13: Bluetooth pairing issues PENDING VERIFICATION — no local document covers this. Do not improvise a diagnostic script for this symptom. ### Lesson 14: Firmware update failure PENDING VERIFICATION — no local document covers this. Do not improvise a diagnostic script for this symptom. ## Customer Complaints (handling process) PENDING VERIFICATION — no documented customer-complaint intake or triage process exists anywhere in this project. The 10 real symptom lessons above are the only verified diagnostic content available to use when a complaint comes in; match the complaint to a lesson before escalating. ## Dealer Complaints (handling process) PENDING VERIFICATION — no documented dealer-to-manufacturer complaint/escalation process exists anywhere in this project. ## Service Workflow PENDING VERIFICATION — no documented RMA/service workflow exists anywhere in this project. The only service-adjacent real fact available is FX-4's fuse guidance: "if the fuse blows again after replacement, there may be an internal malfunction — consult your dealer," which implies a dealer escalation step exists in practice, but the workflow itself is not documented. ## Staleness note `` still says DSP troubleshooting is entirely PENDING — that was true when written, superseded for FP-8A/FP-12A by 's later (see `` Contradiction #1). This course uses the corrected, current knowledge.
Troubleshooting School
Professional · ACADEMY