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**yyonline** · 02-13-2011, 04:55 PM

Re: My first recap -FAIL! Please offer advice.

The symptoms you describe - powering on briefly and then power cutting out - can be caused by a short. When the power supply detects a short, it cuts power to the system. I'd pull the board out and very carefully look for any stray bits of solder that may have shorted something out. Hot solder can "jump" impressive distances while you're working, so be sure to look everywhere on the board.

**seanc** · 02-13-2011, 05:08 PM

Re: My first recap -FAIL! Please offer advice.

Can you post pictures of your work so we can check for any accidental polarity swaps etc.

**c_hegge** · 02-13-2011, 06:06 PM

Re: My first recap -FAIL! Please offer advice.

Try unplugging the 4 pin CPU Power connector. If it stays running like that, then the problem has to be around there. As seanc said, a shot of the board would be helpful.

On a side note, I've re-capped four of these exact boards so far and in each case, I've used polys around the CPU and it's worked every time. In one case, I even replaced the 3 1800uF 16v lytics with 470uF polys and it worked. Therefore, the poly mod itself wouldn't be the problem.

**Davisdog** · 02-13-2011, 09:29 PM

Re: My first recap -FAIL! Please offer advice.

Thanks for the replies. I have just finished looking over the mobo for obvious shorts. I couldn't find any, but there are two very small suspect areas that I'm gonna give some attention to tomorrow evening. After that, I'll try running it without the 4 pin connector as c hegge suggested.

One thing I'm concerned about: I don't have any alcohol or flux cleaner, so my solders look pretty nasty right now. Will the burnt flux cause any problems? Also, will stray solder that is not touching any terminals cause any problems (like just in a random spot on the green pcb, but not touching any exposed metal?) I don't see any of that, I'm just curious.

I will try for some photos tomorrow night if the above does not work.

Davisdog.

**kc8adu** · 02-13-2011, 09:45 PM

Re: My first recap -FAIL! Please offer advice.

any caps in backwards?

**Davisdog** · 02-13-2011, 09:50 PM

Re: My first recap -FAIL! Please offer advice.

No caps in backwards. I made a chart before I began and checked it several times both during the surgery and in post-op. I verified before I began that the half-moons indicate the negative side on all of the caps on this board. I actually printed out one of c hegge's photos of his board and marked it up as my road map.

**bigbeark** · 02-14-2011, 01:24 PM

Re: My first recap -FAIL! Please offer advice.

Originally posted by Davisdog View Post

I did have some trouble getting some of the old caps off and I admit I may have jacked up this board.

If you had to pull hard to get the cap legs out of the holes, you may have dislodged an internal trace or "via".

Before removing caps you should apply fresh new solder The remelt the joint and work the capacitor back-and-forth until one leg comes out, then reheat the other leg and do the same until it comes out. For best results you need a good-sized chisel tip, at least 1/8 inch and an iron of 50 watts or better.

Newer boards are much harder to work on because of the no-lead solder.

The cap legs should slide out of their holes easily, with no feeling of pressing hard on the cap.

**kiddznet** · 02-14-2011, 04:16 PM

Re: My first recap -FAIL! Please offer advice.

I'm with bigbeark
This bad boy 80W iron has them caps jumping off the board in fright
Easy to put them back on with it as well gives a nice neat pro looking job.Clip the cap legs before fitting

http://www.jaycar.com.au/productView...n&form=KEYWORD

**Agent24** · 02-14-2011, 05:52 PM

Re: My first recap -FAIL! Please offer advice.

I thought an iron like that could damage the board too easily?

**kaboom** · 02-14-2011, 08:40 PM

Re: My first recap -FAIL! Please offer advice.

I almost thought I trashed this one board. Intel OEM for Dell.

Got all the nasty old caps out in the VRM and ohmed out Vcore and 12Vin to the ground plane. Dead short on 12Vin. Here it was- this little solder splash from the hole of one of the 12v caps right to the ground plane. Looked close and found it. Pulled it off with solder wick and no more short. I thought one of the layers was shorting to a via...

Replaced ALL caps and perfection! When I got it, no boot, no nothin. I wasn't stupid enough to 'just try it,' as I saw the craps, both on the board and in the PS. People were blaming software as usual. And just how does software cause no power?

That thing booted right up like nothing was ever wrong. It did get the ol' format n reinstall, since some people 'mistreat' their computers.

All you have now is basic electronics troubleshooting- looking for that short. It's not any different because you're inside a computer. You'll find it.

-Paul

**Davisdog** · 02-14-2011, 09:11 PM

Re: My first recap -FAIL! Please offer advice.

Ok, I looked everywhere for a short. I couldn't find one, but there is a nasty area around where I struggled to get out one of the old poly's (I left the other two old poly's after that experience.) Some of the green is scrapped off in that area, but upon close inspection, there does seem to be space between the solder and the scrapped off area, so I'm not sure that's the problem. I am concerned about the internal damage I might have done there.

Attached are some photo's before and after the surgery. I hope they show enough detail, as they are the best I can do right now. I'm having camera issues that rival my computer issues at the moment. The first three photos are pre-op, the rest are post-op (maybe post-mortem.)

I did try the power cable suggestion - no difference. I tried it with one and two fans, with and without: memory, HD, processor, and just about every combination of all of that, it keeps doing the same thing.

Attached Files

**Agent24** · 02-14-2011, 09:22 PM

Re: My first recap -FAIL! Please offer advice.

Have you actually tested for shorts with a multimeter or just looked for them with your eyes?

There could be stuff going on between the underside of the capacitor and the board, where you can't see it..

**bigbeark** · 02-14-2011, 09:53 PM

Re: My first recap -FAIL! Please offer advice.

Originally posted by Davisdog View Post

Ok, I looked everywhere for a short. I couldn't find one, but there is a nasty area around where I struggled to get out one of the old poly's (I left the other two old poly's after that experience.) Some of the green is scrapped off in that area, but upon close inspection, there does seem to be space between the solder and the scrapped off area, so I'm not sure that's the problem. I am concerned about the internal damage I might have done there..

When you say struggled to get out, what actually happened. Did you really yank on it?
Did you try to remove the other 2 polys? What size iron are you using? It's possible you could have broken the connection inside one of the other polys if you tried to remove them.

Whichever cap refused to slide out easily is probably the one causing the problem. Try reflowing that one.

Please test the board out of the case, see if that makes a difference. You've got a lot of excess leg-length on some of those caps, could be shorting to the case.

**Davisdog** · 02-14-2011, 10:26 PM

Re: My first recap -FAIL! Please offer advice.

bigbeark,

I did test it outside of the case, sitting on cardboard. Same deal. I'm using a 30 watt pencil style iron, from Radio Shack. One of the legs of the problem cap had broken off inside the hole. I had a heck of a time getting it out. When I was done, the hole looked pretty nasty. I have already tried reflowing it, along with all the rest, but there was no change. I didn't mess with the other poly's at all.

I don't have a multi-meter, so all I've done is a visual inspection. I would like to get a multi-meter, but my repair budget is getting pretty thin. My wife is getting to the point where she wants me to just go buy a whole new computer. I would like some recommendations on affordable meters though.

**Agent24** · 02-14-2011, 11:09 PM

Re: My first recap -FAIL! Please offer advice.

My multimeter was the cheapest one available from Dick-Smith. Normally $30 I got it for $20 on special.

So that's about $15-$20 US, I guess.

A cheap one will be better than nothing , but try to avoid anything _really_ cheap (say from a local Chinese shop for $2.50 or something)

Something cheap from RadioShack should be OK, but you might be able to get a good deal for a better meter 2nd hand on eBay or something. Garage sales where people don't know the value of things are always a good place if you get lucky

**retiredcaps** · 02-14-2011, 11:19 PM

Re: My first recap -FAIL! Please offer advice.

Originally posted by Davisdog View Post

I would like some recommendations on affordable meters though.

Two recent threads on the subject of affordable meters ...

https://www.badcaps.net/forum/showth...ht=entry+level

https://www.badcaps.net/forum/showth...end+multimeter

Your best bet if you have patience and discipline is to buy one off ebay when it is mispriced. I have seen a few $150 multimeters from good brand names go for $20 to $25.

Avoid anything that even looks like the generic 830B multimeter.

**Agent24** · 02-14-2011, 11:44 PM

Re: My first recap -FAIL! Please offer advice.

Originally posted by retiredcaps View Post

Avoid anything that even looks like the generic 830B multimeter.

I just looked that up... and it looks just like what I have

Mine has been going for years, sure it's cheap, and probably quite nasty, but its infinitely more useful than no meter at all. Also I can connect it to the mains and it doesn't explode, so it must be doing something right

Then again, Dick Smith doesn't exactly sell total crap, so perhaps they got the version that actually goes through the QA department.

**kaboom** · 02-15-2011, 12:54 AM

Re: My first recap -FAIL! Please offer advice.

Reflow everything in the VRM and by the DIMM slots. Try to make the solder filets more cone shaped. It's real easy to have a short where the positive lead of a cap has too much solder on it, and that solder breaks through the solder mask and shorts to gnd plane.

I've been known to use a soldering gun

for stubbon areas. With heavy tips and 'trigger modulating', I'm good, but there's still less thermal mass than a large iron. I've never damaged or delaminated a board doing that. Normally, I use a 60w temp controlled Weller and a very old American Beauty. Get in, get hot, and get out.

I would be doing someone a disservice if I told 'em to use a gun. I know just how far I can go with that. You don't want to practice on your first recap!

Agent24, keep that 830 well away from 240V! Such behavior is right up there with little johnny sticking knives in outlets

-Paul

**Agent24** · 02-15-2011, 03:54 AM

Re: My first recap -FAIL! Please offer advice.

Originally posted by kaboom View Post

Agent24, keep that 830 well away from 240V! Such behavior is right up there with little johnny sticking knives in outlets

Well it's several years old and it's been OK so far, used it many times on SMPS mains circuits and checking primary filter capacitors for charge etc, I don't see any reason to doubt its capability - im sure it would have gone up in smoke by now if it had any major issues.

But I do not deny that it's a cheap meter, and would certainly recommend something better if one can afford it.

(Say, something that can measure amps on AC for a start!)

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My first recap -FAIL! Please offer advice.

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