⚠️ : This board connects directly to 220V AC. The primary capacitor can hold a lethal charge (310V) for minutes after unplugging. Discharge through a 10kΩ/5W resistor before probing.
Whether you are repairing a failed power stage or modding the unit for a new purpose, the schematic is not just a piece of paper—it is the difference between a revived unit and a paperweight. As technology evolves, the preservation of these technical diagrams ensures that reliable hardware remains in service long after manufacturer support has ended. jymc220bi schematic 2021
| Pin | Name | Function in 2021 Rev | |-----|----------|-----------------------------------------------| | 1 | BAT | Battery positive (direct connection) | | 2 | GND | Power ground | | 3 | CHRG | Open-drain charge indicator (active low) | | 4 | FULL | Open-drain full indicator | | 5 | KEY1 | Single button input (pull-up internal) | | 6 | LED1-4 | Multiplexed LED outputs (sink current) | | 7 | SW | Inductor pin for boost converter (to 2.2µH) | | 8 | VOUT | 5V boosted output | | 9 | ISET | Charge current set (resistor to GND) | | 10 | NTC | Battery thermistor input (10k NTC typical) | ⚠️ : This board connects directly to 220V AC
before inspecting the board, and discharge the large capacitors before touching the circuit to avoid electric shock. Whether you are repairing a failed power stage