Help on epox 8k3a recap, no post

[valvestate]

hey everybody. i just recapped my epox 8k3a board and now its not posting. does anyone have any experience as to what i can do to fix it? its my second recap of this board, first time i recapped i scavenged gsc's (had nothing else on hand and a thin wallet) off an older epox and it rocked for about a year. they bulged and started having spontaneous power down issues under heavy load (WoW). this second time around i replaced all the 10v 2200uf caps with mallory's and its a no go. board posted just fine before i pulled the gsc's out. tried the wonderful reset trick and cleared cmos. sorry i have no pics at the moment. caps i bought were allied stock number: 852-6504. im thinking they might not be good enough for pc mobo use... any ideas?

[Per Hansson]

Re: Help on epox 8k3a recap, no post

Umm, are they even LOW-ESR?

They need to be... Contact Big Pope if you're outside the US or Topcat if you're in the US if you have troubles sourcing caps...

[yanz]

Re: Help on epox 8k3a recap, no post

that was what i thought too.. i have recapped a 8k3a before, the ones at vrm output (near proc) are gsc 2200 6.3v and else are gsc 2200uf 10v..
my guest is your mallorys aren't low esr enough for the board to function properly.. though have to look at mallorys caps datasheet for sure..

[valvestate]

Re: Help on epox 8k3a recap, no post

what esr rating should i be looking for, for said value caps? when i bought the caps that i did, i picked the lowest esr ones in the list which was 0.14Ohm.

[valvestate]

Re: Help on epox 8k3a recap, no post

Edit for above: I think I see my issue, the Mallory caps are SK series which are labaled general purpose caps. I would still like to know, however, the esr rating I'm looking for to get this board working. It's the most stable board I've ever had even after tweaking every freakin setting in CMOS. I'd hate to see this board get the axe. I had an Asus A7S333 previously, yuck. The reset button was my only friend on that piece of crap.

[yanz]

Re: Help on epox 8k3a recap, no post

i personally will only recommend japan caps or samxons for recapping..

i suggest you not to take caps with higher esr than panasonic FC or nichicon PW as i know they at least will works.. that means caps that you need shouldn't be higher than 45-60 ohm esr.. (that's only my general rule of thumb). caps on vrm output are even should be much lower esr for optimum use (panasonic FM, ruby MBZ, sanyo WG etc), but i think caps like panasonic FCs or nichicon PWs will do if you push it..

2200uF 10mm 10v Caps

2200uF 10mm 6.3v Caps

just to give you the example (esr ~ impedance):



taken from "Comparison tables between 5 major Japanese Low ESR capasitors"
https://www.badcaps.net/forum/showthread.php?t=1822

[yanz]

Re: Help on epox 8k3a recap, no post

It's the most stable board I've ever had even after tweaking every freakin setting in CMOS.

agree with that i still have one 8k3a running to this day with tbred 1700 @ 2ghz running FAH..

caps that i ever use for 8k3a boards : panny fc, sanyo wg, ucc lxz, ruby mbz. they all works. at least good enough..

[gonzo0815]

Re: Help on epox 8k3a recap, no post

Any cap in the region of 0.0xxOhm is considered a low esr cap.
For boards i think it should be below 0.050Ohm, depending on the design and total number of caps.
Generally, i would not recommend doing repeated recapping of a board, as you can`t do it unlimited times.
I am not sure, if your problem is really caused by the higher esr, in think it is more likely, that there is something damaged caused by repeated soldering.

[kc8adu]

Re: Help on epox 8k3a recap, no post

Any cap in the region of 0.0xxOhm is considered a low esr cap.
For boards i think it should be below 0.050Ohm, depending on the design and total number of caps.
Generally, i would not recommend doing repeated recapping of a board, as you can`t do it unlimited times.
I am not sure, if your problem is really caused by the higher esr, in think it is more likely, that there is something damaged caused by repeated soldering.

thats what i was thinking.
but i have seen several vp6 with marginal caps not bulging at all where the vrm would shut down.
get the right parts and do over. take care to get em in right.

[yanz]

Re: Help on epox 8k3a recap, no post

that means caps that you need shouldn't be higher than 45-60 ohm esr..

umm... it's typo, i mean 45-60 mili ohm, my bad.. boards for p4 or amd k7 need very low esr caps for their vrm.. but depends on design like what gonzo said

check also the page that willawake created:
Tips after a Failed Recapping
http://www.capacitorlab.com/failed-recapping/index.htm

[valvestate]

Re: Help on epox 8k3a recap, no post

When I have to time to do some digging on some caps, I'll check with you guys when I find one I think will work before I make the order. Thanks for the help

[valvestate]

Re: Help on epox 8k3a recap, no post

ok, found some rubycon mcz's. problem is i cant find a 6.3V @ 1500uF, only 1200uF or 1800uF. Which do you think I should choose? I'm guessing the bigger one as I have a little overclocking in mind. I bought the mobile version of my processor so its unlocked from AMD and doesn't consume as much power.

[gonzo0815]

Re: Help on epox 8k3a recap, no post

Can`t you source some 2200uF ones? i would not reducing the capacitance, especially if you intend to oc.
Your mobile CPU will not consume less if powered with higher voltage and set for higher frequency.

[valvestate]

Re: Help on epox 8k3a recap, no post

i just put an order for the new rubys. theyre comin overseas, so it could take a while to get them. ill let you guys know how things turn out. thanks a lot for your help guys.

[valvestate]

Re: Help on epox 8k3a recap, no post

I got MCZ's in and its a no go either. It's got me stumped and bummed a bit. This is the third try at getting this thing to work. I've looked the board over and couldn't spot anything wrong except one square lifted at the corner but most of it was still intact and I got it soldered down. Any ideas? All the components are known to be working. Tried 2 cpus, 2 vid cards, and 2 psus. It's a great board and don't want to have to part with it

[valvestate]

Re: Help on epox 8k3a recap, no post

can i get a clear picture of an mcz in case i got ripped off? thanks

[gastorgrab]

Re: Help on epox 8k3a recap, no post

See here; https://www.badcaps.net/forum/showthread.php?t=588

[valvestate]

Re: Help on epox 8k3a recap, no post

well i broke down and bought a new board. the exact same one thanks for your help guys

[valvestate]

Re: Help on epox 8k3a recap, no post

got a new old 8k3a board. its got a pooped 1500 cap but no biggie. posted right out of the box. got 5 caps changed so far, half a million to go. i think this board is better than my last one though. it overclocks fsb really well compared to the last one, though the cpu vrm teapos are still in good condition unlike the last one had (maybe last was a bad egg/damaged?). i dont see much point in waiting for them to blow, so out they go.

[valvestate]

Re: Help on epox 8k3a recap, no post

All is well with the new 8k3a. 23 caps changed to mcz. Old ones were GSC and Teapo. It overclocks decently, but heat is now my issue, 140 degrees is not cool. I'd love to get a peltier on it, but that's for another time thanks for all the help guys