Major Caps / Minor Caps ??? Difference?

[linuxguru]

Re: Major Caps / Minor Caps ??? Difference?

If you have the time and inclination, go ahead and recap the big primaries. It will give some additional margin against spikes and brown-outs. I usually use Rubycon 680uF/200v, which is usually available for less than a dollar (equiv.) locally, to replace the 330 or 470uF primaries.

I also replace the kludged 2x FR302 3A rectifiers on the +12v rail with a real 20A, 200V TO220 rectifier whenever I encounter one, in the el-cheapo PSUs which are otherwise OK.

[Rainbow]

Re: Major Caps / Minor Caps ??? Difference?

And if there is any cap on the primary side of auxiliary power supply, replace it too.

[PCBONEZ]

Re: Major Caps / Minor Caps ??? Difference?

There you go posting misleading crap again....... Everyone knows this is not the truth, except you....because you're so much more enlightened and intelligent than the rest of us.

KC8 hit it on the head, 470uF and up will cure 99.9% of boards with bad caps. It's been my experience, and everyone else's experience that I know who recap boards.

~~~~~~~

That (470uF) makes a lot more sense than the 1000uF and up I saw in here before.

If it truly cures 99.9% of bad cap MoBo's then this should be the 'Official' Rule-of-Thumb.

Ya think?

.

[PCBONEZ]

Re: Major Caps / Minor Caps ??? Difference?

On the other hand I have yet to encounter one argument about why NOT exchange the small caps.

~~~~~

Well, because I have 6 boards with 45-48 each on them (JUST the 'minor' caps) and I don't wanna replace 270+ capacitors for the hell of it.

DUH!

.

[Rainbow]

Re: Major Caps / Minor Caps ??? Difference?

Recently I had to recap the small 10uF SMD caps on two MSI boards (about 15 of them on each). Watch out for them on MSI boards - they don't show any signs and many of them are connected in parallel with some bigger caps. The bad ones measured 10ohms ESR while the good ones 3ohms.

I replaced them with G-Luxons from dead PC Chips board which were all good - there was 40 of them there (MicroATX), which makes me think that it was a really good board.

[gonzo0815]

Re: Major Caps / Minor Caps ??? Difference?

OMG MSI should just stop selling sutch crap.... if now the MLCC `s are failing, what else will be cheaped out after that?

[PeteS in CA]

Re: Major Caps / Minor Caps ??? Difference?

Those SMT caps Rainbow referred to may be lytics. If the decoupling cap for a particular IC goes bad, that might be enough to disrupt the operation of that chip. Decoupling caps usually aren't stressed that much, but if a lot of totem pole outputs go low synchronously, that can be a very substantial, though very very brief, spike of current.

[Rainbow]

Re: Major Caps / Minor Caps ??? Difference?

I'm talking about that small SMD electrolytic caps which are often bad on MSI boards. They stink like rotten fish when removed. They're around clock generator chip on some boards - and can cause unstability.

[kc8adu]

Re: Major Caps / Minor Caps ??? Difference?

those small sm lytics are always bad on msi boards and just about anything that has them after a few years.
i have 2 standard c5900 radios that i had to replace every one of them in.
each had 1 good one in it....in the microphone!
replaced them with tantalums.
got 3 more of these sets on the way.shame on you marantz japan/standard radio!
and replaced those bulbs that can cook the lcd with led's
these were around $900.00 new.

[Rainbow]

Re: Major Caps / Minor Caps ??? Difference?

I've seen them on Asus P3 boards too and they were good. MSI probably used Chhsi or some other crap while Asus used some decent brand.