Half-bridge fix

[ratdude747]

Re: Half-bridge fix

I'm sure half the 'killer 5vsb cap' problems are just the resut of using bad caps like fuhjyyu and that a panny or ruby in the same place would do fine, although in other cases it may well be because it's under too much stress.

the heat of the resistor is the issue. so thats why I'm thing to go with a non-lytic

maybe high-esr poly?

[momaka]

Re: Half-bridge fix

maybe high-esr poly?

High-ESR is what causes the 5vsb of those 2-transistor PSUs to go kamikadze in the first place. If anything, you should use a LOW ESR cap in that spot.

With that said, I don't think you'll find a suitable polymer cap for that. High-voltage (as in 25-50v) polymers aren't as common as the lytics, so they are more expensive. Also, polymers tend to be fat and short compared to lytics - so you may have a problem fitting one in there (provided you do find one at all).

A high quality electrolytic cap should be fine if you don't want to do a DM311 mod.

I did that for an old Deer PSU that I'm currently using in a Pentium III computer. After recapping the PSU, 5vsb came up exactly to 5v. That PSU is actually pretty decent, though, as there isn't that much heat in the 5vsb circuit itself. I've seen some other PSUs where heat really is a problem in the 5vsb section and a DM311 mod is the only way to go.

[ratdude747]

Re: Half-bridge fix

FYI, i found the 2nd thread on the orignal topic (600w xfinity 5vsb fix). the discussion is now there

reason I siad high ESR was because poly caps are so low esr that a high esr is just like a GP lytic more or less... but this discussion belongs in the other thread.