The Dynapath F20 is a DC power supply module that powers older Delta 10/20/30/40/50/60 controls; it is highly sensitive to voltage ripple and often fails, causing spontaneous reboots or watchdog timeouts. Common failure modes include degraded output regulation, overheating of the internal regulator, or loss of the “P.F.” (power‑feedback) connection that feeds back line voltage to the control board. First‑check steps: verify 110 V input with a multimeter and confirm proper polarity; inspect the PSU for visible burn marks, swollen electrolytics, or loose terminals, especially the white “P.F.” lead; then test the output under load (≈3–5 A) to ensure it stays within spec and that the control board’s watchdog flag remains clear.[oss-gpt-20b]