Help Needed for DS430n PCB

[dishdoctor]

Sorry if in wrong place but what are the values of the ceramic disc capacitor on the board place VDR2500 on a DS430n digibox ,it is the shape of a chocolate smartie in red....but nothing printed on it, thanks

 

[Llew]

It'll be a varistor to prevent current surges in your power supply. As to the value, if it's in the input to the supply, it'll need to be rated at 250V.

Not knowing your box, the exact current rating I have no idea, although it's probably much the same component as used in many digibox PS's.

 

[dishdoctor]

Thanks,
But one of the capacitors is rated 400v 68uf,so voltages can differ from the mains input,and they go with quite a bang!.

 

[Llew]

Well that's the point in having a varistor in circuit - it simply shunts excess current to earth when voltage spikes occur in the power line. It's the operating voltage that I was referring to. So the voltage value is chosen to equal or exceed the power supply's working voltage. Admittedly choosing one rated at 250V would probably give minimal protection, so to be on the safe side choose one rated at, say, 275V.