Motorola ts907 low hv

[timmy]

Originally Posted by old_tv_nut

I don't know where you got the 135v rating, but forget it.

It's a 3 watt 2700 ohm resistor, and will dissipate 3 watts when the voltage is 90 volts DC. (P = (V^2)/R). So, if the specified wattage rating is 3 watts, the circuit was designed to apply less than 90 volts to that resistor. Of course, a circuit fault might put more voltage across a resistor than intended, and that would have to be fixed, and the resistor would indicate that by overheating and smoking.

Edit: resistor voltage ratings are usually for momentary voltage that might cause the resistor to arc over. Typical max voltage rating for discrete resistors might be 200-600 volts, but as you see, for DC, the wattage rating may be exceeded long before the voltage is. AC or pulse current will be different, as r.m.s. current determines the power while the peak voltage determines whether the voltage rating is exceeded.

The voltage rating was listed on the mouser site where I got it and this voltage is 275 dc from the power supply so I just want to make sure because these resistors get hot but it is 3 watt same as what was in there. And it’s a wire wound. These resistors are small bearly half inch.