caso de reparación
KA3843 fuente auxiliar: sin 24V Rail
Utiliza esta página cuando the fan, relé, placa de control o display is dead because the auxiliary 24V supply is missing o pulsing.
Measurement order
| Node | Valor esperado | Si es anormal |
|---|---|---|
| Bulk DC entrada | Present at auxiliary supply entrada | entrada rectificador o bus path falla |
| KA3843 VCC | Rises to arranque threshold | Open arranque resistencia, dry VCC capacitor, shorted chip |
| Switch drain | Switching forma de onda after arranque | PWM chip o MOSFET falla |
| Secondary 24V | Stable salida under load | Secondary diodo/capacitor/load short |
| PC817 realimentación | Regulates without hunting | Referencia o optocoupler falla |
Common repair parts
- Arranque resistencia.
- VCC electrolytic capacitor.
- KA3843/UC3843 PWM chip.
- Switching MOSFET.
- Rectificador secundario diodo.
- PC817 optocoupler y reference device.