TNY266 Shunt resistor value

Hi,

I'm trying to repair a power supply from a dryer equipment.

The schematic / pcb is based on the compponent placement as in figure 17 of the TNY263-268 datasheet.

I changed the TNY-266 and most of the parts around, but it seems that the shunt resistor which seems to be used as a fused is broken. I found in a low power design guidea value of 8.2 Ohms, but I'm not sure about this.
Is someone able to provide me deeper details around this S resistor, and how to determine its value ?

Thanks by advance,

       Samuel

Up :-(

Hello  Samuel,

Thank you for interested in Power Integrations products.

The Fusible resistor accomplishes several functions:

A. Inrush current limitation to safe levels for rectifiers D3 and D4;

B. Differential mode noise attenuation;

C. Acts as an input fuse in the event any other component fails short-circuit (component fails safely open-circuit without emitting smoke, fire or incandescent material).

If a fusible resistor is selected, it should be a flameproof type and, depending on the differential line input surge requirements, a wire-wound type may be required. Care should be taken in using metal or carbon film types as these can fail simply due to the inrush current when AC is connected to the supply.

Best Regards

Jia