Power Board Caps

[GatorGnet]

I need to replace several caps on a power board for a LCD monitor. The list of caps I need are as follows:

220uf 25v
1000uf 25v
1000uf 10v
2200uf 10v
330uf 25v

I can only access a few of these right now but some are close. Example, I can get a 220uf but its 35V instead of 25v. Same with the 1000uf. I can get 35 v ones but not 25 and 10v. Would I be able to replace them with the higher 35v ones?

I also can't get the 330 right now, would a 470uf 35v work?

These are all electrolytic caps but I only have an axial-lead one in 2200uf. Ok to use?

As always thank you!!!!

 

[GatorGnet]

Also, only three of the caps appear to have a "bulged" top on them. Is this an indicator that those are the bad ones?

 

[ronv]

Yes to all including the bad ones.

 

[Exo]

You can use caps rated for a higher voltage but for these fast switching DC-DC purposes you need to get capacitors with a low ESR or they will fail again.

 

[GatorGnet]

I replaced four caps and the monitor works again. But now it has a high freq "wine" in the back similar to crickets on speed. It gets louder when you turn the brightness up on the monitor. Any ideas?

Here is a page I used as a reference. This is the model of monitor I have.

**broken link removed**

 

[tvtech]

You can use caps rated for a higher voltage but for these fast switching DC-DC purposes you need to get capacitors with a low ESR or they will fail again.

Original poster goes to electronics shop: "I need some low ESR capacitors please".

Salesman:"Huh??"

Exo..all Electrolytic Caps are low ESR until they dry out/vent/overheat/wear out/burst or so on.

Maybe you mean proper SMPS Caps rated at 105 Degrees instead of the normal 85 Degrees...

Cheers

 

[GatorGnet]

lol No joke. Going into Radio Shack anymore is a fun trip. They are more interested in selling cell phones. Component parts are just a few drawers in the back.

 

[Exo]

Original poster goes to electronics shop: "I need some low ESR capacitors please".

Salesman:"Huh??"

Exo..all Electrolytic Caps are low ESR until they dry out/vent/overheat/wear out/burst or so on.

Maybe you mean proper SMPS Caps rated at 105 Degrees instead of the normal 85 Degrees...

Cheers

Capacitors made for these purposes are marketed as "low ESR".
Aluminum Electrolytic Capacitor | Passive & Electromechanical | Panasonic Industrial Solutions Global look at the FR series - "low ESR" listed as the main feature. These are the caps you want for SMPS purpses, DC-DC conversion and so on.

 

[crutschow]

There are two reasons to use low ESR capacitors in high frequency switching supplies:

1. The reduce power loss, thus temperature rise and shorted life of the capacitor.

2. The reduce voltage ripple in the output.