Boards with incorrect capacitor polarity on stencil

[willawake]

I have seen two boards now namely the Asus TUSL2 and the Asus CUSL2-M where the board stencil for the negative lead of the capacitor was totally opposite for all the caps on the board.

Be careful if you are new at recapping. It is most likely that the board stencil is wrong and the orientation of the original caps on the board is correct.

[bushytails]

Also, C390 on the MSI 694d Pro 1.0 is stencilled backwards.


--Randy

[BluBlur]

Looks like I fell into complacency, recapping several 1500uf6.3v and all the 1000uf6.3v on a piece of Asus CUSL2-C backwards! The stencil marking was also printed in the reverse direction. Have a CUV4X and Asrock board, both stencil marking are also reversed.

4 of the 1000uf6.3v caps vented within few seconds of bootup. The board boots up, but counts RAM slowly and keyboard does not respond. After realising the horror, I have disconnected every damn component off it.

Now, can I reuse those reversely connected caps? I hope the board is okay after all the affected caps are redone.

[willawake]

yep asus is using backwards stencil on many boards and graphics cards, perhaps all.

you cannot use the reversely connected caps, they are failed now. Please recap again with new caps and see if all is well.

can we see a pic of the failed caps.

what caps did you recap on the cusl2? all the 1000uf OST i guess but what else? the nichicons? did you have actual fail of the caps or was it just a precaution repair (i have 3 cusl2 and 1 tusl2)

[BluBlur]

yep asus is using backwards stencil on many boards and graphics cards, perhaps all.

you cannot use the reversely connected caps, they are failed now. Please recap again with new caps and see if all is well.

can we see a pic of the failed caps.

what caps did you recap on the cusl2? all the 1000uf OST i guess but what else? the nichicons? did you have actual fail of the caps or was it just a precaution repair (i have 3 cusl2 and 1 tusl2)

Thank you for your advice!

Yeah I have replaced all OSTs on this board. OST 1000uf6.3v and 1500uf6.3v (the 7 near the PS2 connectors, 2 near the DIMMs and 1 just beside the Northbridge) are found longside the Nichicons. Nichicon 1500uf6.3vs are found in smaller quantities, thus I wonder why Asus did not cap the 1500uf6.3v parts completely with a single vendor.

It's more like a precautionary repair, but I have seen 2 of the 1000uf6.3v caps very very slightly buldging.

Pic coming shortly...

[willawake]

I wonder why Asus did not cap the 1500uf6.3v parts completely with a single vendor.

price and availability.

[BluBlur]

Here's a picture of the botched up operation...



I have a Gigabyte GA-6OXT that boots up fine, but the 2 GSCs are going to belly up. Wonder the remaining OST 3300uf6.3v and HOYO 330uf25v are reliable?



Another question for you willawake. I cannot find the 3300uf6.3v locally in Singapore. What I found was either some odd brand (Elite) and it's 12.5mm in diameter. The maximum temperature rating is 85oC. Although I found that 12.5mm caps can fit onto the GA-6OXT (lead ports fit in), but can I use 3300uf10v part for it?

[willawake]

thanks for the pics

it is recommended only to use brands rubycon, panasonic, nichicon, sanyo united chemicon for a proper repair. Also you must try to find low esr caps these are usually rated at 105oC but even that rating is not a guarantee that the series is low esr. Because your "elite" cap is rated at 85oC it must be a standard cap and is no good for motherboards.

You can try the following companies for low esr caps. Farnell has the Rubycon ZL and RS has the Panasonic FC. I have bought 3300 from RS before in panasonic FC. they are also 12.5mm

Singapore - Farnell Newark in One - http://sg.farnell.com
Singapore - RS Components - http://www.rssingapore.com/

There are also these companies in your region which i have noted on these boards several times but nobody bought from them yet. They have really excellent caps but i dont know about their service / delivery costs.

China - Waifong - http://www.waifong.com/
Hong Kong - Waifong - http://www.waifong.hk/

for the Gigabyte GA-6OXT it is recommended to replace all GSC, OST and CHOYO. they are all crap. the 330uf25v choyo it is recommended to replace with 1000uf16V. probably you cannot find similar replacement value. i have done similar replacement on a GA7-ZXE

[BluBlur]

Thanks again. I have tried both Farnell and RS, both don't seem to carry 3300uf6.3v How about 3300uf10v, can I use the latter for GA-6OXT even though the current OSTs are rated 3300uf6.3v?

I could find the 330uf25v easily. The more problematic part is the 3300uf6.3v. If I can use higher voltage part, things will be easier.

[willawake]

10V will be fine

[BluBlur]

Re: Boards with incorrect capacitor polarity on stencil

Just some quick updates. Have recapped the CUSL2-C, the problem remained. Looks like I've caused an irreversible damage

The 6OXT was also given a complete overhaul, the CHOYO and GSC caps changed with Panasonic FCs, and the OST caps with Rubycon ZLs. It's being primed for stability testing now. Looks good for this

[willawake]

Re: Boards with incorrect capacitor polarity on stencil

Have recapped the CUSL2-C, the problem remained. Looks like I've caused an irreversible damage

shit..i am sorry dude, any ideas guys?

send it to Yanz if you are gonna throw it away.

[yanz]

Re: Boards with incorrect capacitor polarity on stencil

sure i'd love to take it

but it's still hard to believe that those rubycon YXG are vented. YXG or YXF are known to be good, what do you mean by "vented", are they leaking/bulged...?

[willawake]

Re: Boards with incorrect capacitor polarity on stencil

Yanz : board was recapped with several 1500uf6.3v and all the 1000uf6.3v but incorrect polarity used. those caps vented on boot. what do you think, is the board toast?

[yanz]

Re: Boards with incorrect capacitor polarity on stencil

ow, i missed this part..

Looks like I fell into complacency, recapping several 1500uf6.3v and all the 1000uf6.3v on a piece of Asus CUSL2-C backwards! The stencil marking was also printed in the reverse direction. Have a CUV4X and Asrock board, both stencil marking are also reversed.

4 of the 1000uf6.3v caps vented within few seconds of bootup. The board boots up, but counts RAM slowly and keyboard does not respond. After realising the horror, I have disconnected every damn component off it.

what on my mind:
- make sure every component that was attached to the mobo are still good (including vga, cpu, mem, etc)
- make sure the new caps are placed with the same polarity as the originally bad caps. it would be easy if the polarity was totally opposite from the stencil.
- make sure to get a clean solder joint (clean work)..
- check the vrm. i have a friend that i have him done for me.
- more spesific about the (after recaping) boot syndrom (what did he meant about "problem still remained")..

more than that i have no idea, maybe the psu also has blown, given that those "reversed polarity caps" could cause a "chaos" for that few seconds in circuitry ...

Neo's idea of "letting the mobo warmup before testing" also should be considered..

what would a pro like you all think about it?

[BluBlur]

Re: Boards with incorrect capacitor polarity on stencil

ow, i missed this part..



what on my mind:
- make sure every component that was attached to the mobo are still good (including vga, cpu, mem, etc)
- make sure the new caps are placed with the same polarity as the originally bad caps. it would be easy if the polarity was totally opposite from the stencil.
- make sure to get a clean solder joint (clean work)..
- check the vrm. i have a friend that i have him done for me.
- more spesific about the (after recaping) boot syndrom (what did he meant about "problem still remained")..

more than that i have no idea, maybe the psu also has blown, given that those "reversed polarity caps" could cause a "chaos" for that few seconds in circuitry ...

Neo's idea of "letting the mobo warmup before testing" also should be considered..

what would a pro like you all think about it?

Hi yanz, thanks for your assistance!

- All components are good. I have tested a recapped MSI BXMaster and Epox EP-3ETM with the CPU, RAM, VGA card.
- Yes, all the wrongly soldered ones were removed and recapped with polarity checked at the end
- Verified too
- The checking of VRM seems difficult from one of the past thread. Have checked the board physically for burnt FETs (sorry I'm a noob at electronics, are FETs VRMs?), none at all. Nevertheless will try to get the VRMs checked...
- The board does boot, but the keyboard does not respond upon bootup. If it responds, there is a lag time and it completely fails after a few taps. RAM counting is stuttered; the number runs but stops for a split second and continues counting, but the split stopping repeats and repeats until the entire capacity was cleared.