IOTA DLS‑90/IQ4 is a 12 V, 90 A AC‑to‑DC power converter and regulated battery charger that includes an internal IQ4 smart charge controller for 4‑stage charging. Common failure modes for this unit include overheating of the internal MOSFET array (often due to blocked ventilation or excessive load), degradation of the output capacitor bank causing ripple spikes, and failure of the IQ4 microcontroller leading to loss of smart‑charging functionality. For troubleshooting, first verify that the input 120 V AC is within the specified 108–132 V range and measure the output voltage under no load; then inspect the heat sink for dust or obstruction and check the MOSFETs for visible damage or excessive temperature rise; finally review the IQ4 status LEDs or serial log (if available) to confirm proper controller operation.[oss-gpt-20b]