Polymer replacement for Wet cap

[jayjr1105]

I have a Gateway socket 478 board that looks like it was built like a tank (polymer caps and Rubycon MBZ all around the CPU) but it has a single Sanyo WG or WX cap near the 24 pin that is bloated. It's a 2200uf 10v. What's the lowest value I can go with a Polymer? I have a few Panasonic FM's at 1500uf. Is that too low? Otherwise I will have to order.

I'll grab a picture when I get home.

[Andrew F. Ali]

Re: Polymer replacement for Wet cap

I always like to go with the same uF value. The voltage could be higher but defo not lower.

[jayjr1105]

Re: Polymer replacement for Wet cap

I always like to go with the same uF value. The voltage could be higher but defo not lower.

I've heard several times that if you go with solid polymer caps, you can go down in capacitance by a good bit.

[LLLlllou]

Re: Polymer replacement for Wet cap

If it's by the power connector, it's probably either the input cap for a VRM, or decoupling for the memory. FM 1500uf 10V is about halfway between WG and WX in both ESR and ripple rating, so would probably be OK.

A 1500uf 6.3V polymer should be even better.

Replacing wet electrolytics with polymers is not a black and white, one rule fits all, situation. In the output of CPU VRMs where ESR is king, it's quite common for engineers to specify HUGE capacitance solely because it's the only way to get sufficiently low ESR with a wet electrolytic. In this case, polymers with 50% or less capacitance can be substituted, as long as you don't go below the minimum required by the circuit. Unfortunately there's no way to know what that minimum is without doing a shitload of math. 50% is the generally excepted minimum that usually works, but not always. I usually try to stay with at least 8200uf

[Stefan Payne]

Re: Polymer replacement for Wet cap

I have a Gateway socket 478 board that looks like it was built like a tank (polymer caps and Rubycon MBZ all around the CPU) but it has a single Sanyo WG or WX cap near the 24 pin that is bloated. It's a 2200uf 10v. What's the lowest value I can go with a Polymer? I have a few Panasonic FM's at 1500uf. Is that too low? Otherwise I will have to order.

I'll grab a picture when I get home.

Pls make a picture.
I don't know what that Cap is for...

[jayjr1105]

Re: Polymer replacement for Wet cap



Here's the CPU area, they all look good surprisingly