Varistor for Bestec ATX0300 D5WC

[TELVM]

Re: Varistor for Bestec ATX0300 D5WC

... The two varistors in your PSU are installed across each 200V capacitor. The idea behind a varistor is to clamp any power surges that go beyond the 200V rating of the primary caps. If you put a 300V varistor, then it won't protect the capacitor. However, you can't use a 100V varistor either, because the voltage on each cap will be around 165V and may go up to 170 V when your line is 5% high. So that's why you need a varistor rated between 180-200V ...

On my super-duper Oh Deer I installed two '175' between the bulk caps:



On 230VAC they are in series and work like one single '350' of same Joule rating.


Also installed one '300' MOV upstream from the rectifier bridge:

[docchan2000]

Re: Varistor for Bestec ATX0300 D5WC

Update.
Changed my varistor to 200v
Found out that there is a fuse covered with black rubber that does not give a reading on the multimeter. That fix my problem. Thanks everyone.

[docchan2000]

Re: Varistor for Bestec ATX0300 D5WC

Other pics

[momaka]

Re: Varistor for Bestec ATX0300 D5WC

Update.
Changed my varistor to 200v
Found out that there is a fuse covered with black rubber that does not give a reading on the multimeter. That fix my problem. Thanks everyone.

Nice work.
Yes, the fuse is covered like that on many Bestec PSUs. Make sure to insulate the new one, too, especially if it is a glass fuse (which looks like it is).