Electronics Reversing the side Caps are mounted on (was "caps on wires")

I remember seeing a while back someone that had made up a mobo cover and to allow it to fit nicely they had de-soldered the caps off their motherboard and laid them flat against the board.

My questions are:

a) Who was it and what was the mod?
b) Is the motherboard still going strong now?
c) Are there any other concerns I should be worried about doing the same?

I trust my desoldering and soldering skills, I'm more concerned that I am missing something electronic. It's one thing to be able to solder but understanding the actual electronics is kinda beyond me.

I plan to secure the caps once they have been de soldered just for some extra insurance.

Thanks

 

uh, considering most caps don't go through the entire board this should be interesting.

correct me if i'm wrong, but most motherboards are 4 layers; 2 signal (the exterior ones) power, and ground. most caps are mounted REALLY close to the outside.

second the request for pics. I gotta see this for myself.

 

All of the caps I am considering desoldering are all the way through... ie pin protruding.

Pics are posted below

 

I can't see anything stoping you from doing it??

 

mmm, i know the log you mean, its one of the top few in the project logs archive, but i cant for the life of me remember what its called!

as far as i know the mobo is still going...

 

Thanks GS, I will trawl through the ones on there. I have a sneaking feeling that it had a red lighting theme to it or some such.

Either ways I will post up my quick progess in here when I get round to it, which should be tomorrow.

Thanks again

 

if your going to do this get a good iron not one of those $15 cheap ones. something thats easy to control

 

as I said in my first post... my soldering and desoldering skills are fine and I have a full workshop at my disposal... hence why I would even contemplate doing a mod like this...

Right tool for the right job and all that jive.

 

At the sort of frequencies a SMPS (and the processor) uses, cap leads (and PCB traces) have significant inductance - that's why there's a big clump of low-ESR electrolytics inconveniently placed right next to the cpu socket, as close as possible to the right cpu pins. YMMV, but make sure you use a good quality replacement, like Panasonic FM.

 

I'll second that, inductance in the main problem your facing, so keep your leads as short as possible, and use a heavy gauge wire. I would only use what I needed to get the cap to lay over on its side.

 

I'd say just replace the caps with the exact same ones, but with un-clipped legs.

 

Excuse my naivety but I was simply going to unsolder the existing caps, then solder the cables on to the existing caps and remount them. This saves the issues of trying to find satisfactory & matching caps elsewhere.

Thanks for the tip with the heavy gauge wire. I think I'm going to try this on another motherboard before I risk my dual P3 board. I should be able to play tonight so I will post up pics this evening.

 

Spanner to my plans. Even with our desoldering station I was unable to follow through completely with my test motherboard. So i will run you through what happened and there is a big BUT with this.

Had everything all sorted out and as you can see in the photos I'd figured out which caps I was going to desolder and I had made up nice little wires and jive. These shots are of the caps and their pins that I was going to desolder.



And here are the cables I had made up... I had just tinned the ends and cut them down to a reasonable size later on.



Just a quick pair of shots of the equipment we have in the workshop.



So all my intentions were positive and then the caps decided they weren't going to play nice. I had made sure the board posted correctly and everything before I started work. So sucked all the solder outta the joints for the caps I'd targetted but the buggers just didn't want to shift. I didn't want to leave the solder sucker on the pad too long as I have seen pads get sucked up as well. So I was well bummed.

BUT! (told you there was one!) Decided I still needed to test out my theory. We had a blown board of the same type as I am using so i tried to unsolder each of the caps I had targetted on this board and they all came away nicely. So all was not lost. Until I tried the wires... no way were they going to fit, change of plans!

Back to the other board. Desoldered one of the caps on the slotket and then since I couldn't get the wires to fit... I just soldered it back on the reverse side of the board. All back together and we plug in the power cables...

VOILA! Posts! It's as if nothing was changed, though first of all the bugger wouldn't post but that was because the slotket wasn't plugged in completely, whoops. I have pics of the modded slotket but at the moment my webspace is down. Will update later.

 

Well that was some quick downtime on the part of my ISP. So here are the pics I was on about. You can see in the first pic where the cap used to live (excuse the shodding soldering on the right hand side pin, it was getting late). In the second pic you can see the relocated cap nicely covering up the text on the back side of the board.

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The whole purpose of this exercise is so that I can get some nice big heatsinks with 80mm fans on them to fit on these socket 370 chips. Unfortunately some of the caps get in the way. So now i will just unsolder them and mount them on the back face of the board.

Over the weekend I will drill out the motherboard mounting plate and then on monday I should be able to post up the modded motherboard.

Fingers crossed.

 

Cool, if you have space, go for it, thats even better than extending the leads. Just be sure to observe polarity of course

 

Nice.. keep us updated with pics this is looking interesting

 

Impressive work - much neater than using wires, too

 

I'd actually never thought of that, it's much better than using wires as it's still exactly the same, just in a different place. Nice one

 

Everything's looking good so far; best of luck with the mod, and welcome to bit

 

maybe all motherboard designers nog start doing that