New Caps on ASROCK K8 Upgrade 760GX quit working

[ladalet]

Hello, my sister was having some stability issues on her computer. I noticed that 5 of her 3300mf 6.3v caps were bulging. I replaced them with Rubicon caps and the mother board now shows no signs of life. All the filets look good. I am using Kester 63/37 .031 ra flux core solder. I pre-tinned and fluxed the pins prior to soldering and keep the act of soldering to about 3 seconds. I do my best to follow IPC protocols. I am using a Metcal PS2E-01 station and a 700F 1.78mm chisel tip for the ground plain side and a 600F 1.78mm chisel tip for the positive side. I pre-fluxed the filets and used my Soldapult to de-solder the filets. The positive side was clear and ready to pull out. The ground plain side required a little additional heating to pull out.

I have repaired many motherboards over the years and have only had this happen one other time, but it would only occasionally boot up but would only run a few minutes before locking up and would fail to re-boot. I figured that it was just unrepairable. Plus, it was a socket A Foxconn.

Any thought or suggestions would be appreciated. Thanks.

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

This is just an additional note to my previous post. I know this is not a kosher capacitor test, but I do not have a capacitance tester. However, I do think this may be meaningful. When I put my ohm meter on three of the 5 caps the resistance rises to about 58 ohms and stays solid. On 2 of the 5 caps I get infinite resistance or no continuity.

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

I guess I could be a bit more explicit. Does it sound like one or more of my new replacement caps are defective? The motherboard actually worked until I installed the new caps. Plus, 2 out of the 5 don't even register at all on an ohm meter whereas the other 3 uniformly do. Thanks

[momaka]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

I replaced them with Rubicon caps and the mother board now shows no signs of life.

Rubycon or Rubicon?

This is just an additional note to my previous post. I know this is not a kosher capacitor test, but I do not have a capacitance tester. However, I do think this may be meaningful. When I put my ohm meter on three of the 5 caps the resistance rises to about 58 ohms and stays solid. On 2 of the 5 caps I get infinite resistance or no continuity.

The 58 Ohm resistance is probably either from the CPU, the North Bridge, or the South Bridge, depending on where the caps are located. It's not unusual to get such low resistances for the caps in those places.
It's also not unusual to get an open circuit for some of the caps either. Try shorting their leads with a piece of metal to disharge them. Then remove metal and try measuring resistance with your multimeter. If your multimeter shows a resistance quickly and then open circuit, they *should* be okay.

[PCBONEZ]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Did you reset the CMOS after the recap?
Some times they get a bit scrambled.

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Did you reset the CMOS after the recap?
Some times they get a bit scrambled.

Yes I did. Thanks

Rubycon or Rubicon?

Rubycon sorry for the typo. Given the nature of all the counterfeit caps currently on the market, the spelling could be very meaningful.

The 58 Ohm resistance is probably either from the CPU, the North Bridge, or the South Bridge, depending on where the caps are located. It's not unusual to get such low resistances for the caps in those places.
It's also not unusual to get an open circuit for some of the caps either. Try shorting their leads with a piece of metal to disharge them. Then remove metal and try measuring resistance with your multimeter. If your multimeter shows a resistance quickly and then open circuit, they *should* be okay.

Thanks, I was just trying to find and difference that might signal at least signal a hard fail of a cap and thus explain the failure. What you say make sense. Yes, after discharging them and then retesting them with my ohm meter, they do show resistance and the quickly rise to infinity--open circuit).
All but one of the caps I removed from the board do the same. On is just plain open.

I just am attempting to figure out if in replacing the 5 caps I did some damage resulting it a no post or response of any kind where previously there was, or if I have a defective cap. When I received this batch of Rubycon 3300mf 6.3v caps in which one was crushed and a replacement was very quickly sent out by Badcaps. Neither of the two motherboards I used these caps on worked after recapping with them with these caps although they worked (somewhat) before hand. On this motherboard I only changed the 5 bulging 3300mf caps first and tested it before replacing the 1200mv 16v caps to see if that batch of caps might have an issue. Although there was an issue it does not prove anything. It is only mildly suggestive.

Short of a defective cap are there any ideas what could be the cause, or which caps would be the likely cause either due to installation error or defect? Thanks

[Toasty]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Asus is known for reverse cap markings on the board. Are you sure you installed the new ones with the POSITIVE on the WHITE half?

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Asus is known for reverse cap markings on the board. Are you sure you installed the new ones with the POSITIVE on the WHITE half?

SOB!!!! Pardon my acronym. I think you nailed it right on the head. I was so used to the white side being ground that I did not notice that is is reversed on this board. What a lame mistake. Well, that is why forums like this sometimes exist is to straighten out stupid mistakes. Wow, thank you very much. Should I just junk these caps or do you think that rotating them to the correct alignment is adequate? Thanks again.

P.S. I will post the outcome of getting the cap orientation right when finished.

[Toasty]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

A common error. Older and wiser have FUBAR'd worse, trust me.

I'd just rotate them. In all likelihood, and since you did it to all of them, the PSU was shutting down because of the overload. It probably saved them.

How ya do at craps?

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

A common error. Older and wiser have FUBAR'd worse, trust me.

Well, apparently that is a much larger population than I would like to admit

I'd just rotate them. In all likelihood, and since you did it to all of them, the PSU was shutting down because of the overload. It probably saved them.

Unfortunately rotating them changed nothing. I hope replacing them will all new caps will do the trick and I have not toasted the motherboard. I wonder how many times the PCB can tolerated changing caps before damage? I really do not look forward to telling my sister that I broke her computer

How ya do at craps?

CRAPPY!!! but perhaps better than caps--lately at least

Thanks for the help. I know that it is not likely that I will make this mistake again. I really try not to repeat mistakes. The only problem is is that there are so many new ones to discover

[Toasty]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Since the rotation, are -ALL- the voltages supplied to the mobo okay? Checked?

Is the PSU running?

Can you get any voltage readings from the open spots where caps were not placed from the factory?

Did you test the caps and make sure you are not reading a short across any of them?

Since the pic I provided is small and unclear, I can't see if there are any fuses back near those caps. They will be flat, thin, chip SMD devices with little ) ( on each end about a 1/4" long X 3/16" or so. Probably marked F#. Look around.

The FET's may have been toasted, but usually they are -obviously- overheated. If the OCP was working on the PSU, it's doubtful they were harmed.

.

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Since the rotation, are -ALL- the voltages supplied to the mobo okay? Checked?.

Yes, they are good.

Is the PSU running?.

No

Can you get any voltage readings from the open spots where caps were not placed from the factory?.

I have not tried. My Fluke died and is sent in for repair. My current meter only has big awkward alligator clips.

Did you test the caps and make sure you are not reading a short across any of them?.

None are reading shorted. Some start out at 30+ ohms and quickly shoot to infinity. Some start out around 2 to 10 ohms and take several Minutes to reach infinity.

Since the pic I provided is small and unclear, I can't see if there are any fuses back near those caps. They will be flat, thin, chip SMD devices with little ) ( on each end about a 1/4" long X 3/16" or so. Probably marked F#. Look around.

The FET's may have been toasted, but usually they are -obviously- overheated. If the OCP was working on the PSU, it's doubtful they were harmed.

I did not find any -obviously- blown FETs

I did replace all the caps with new ones (correct orientation this time) and the motherboard posted So, I thought great all is good I then replaced the 4 1200uf 16V caps and the board would no longer post again The old caps came out without much heating and the new caps went in without any issues. No joint took over 3 seconds using a 1.5mm Metcal 600 chisel tip, and Alpha .020 no-clean solder--prepped with a little RA liquid flux first. And yes the caps are in correctly this time I think I should have just left well enough alone and stopped when it finally posted. Well, I put the old caps back and it still does not post--arghhhh.

Ultimately I cannot complain as my success rate is still pretty good. It turns out that the last board I had issues with had a damaged usb port that someone had forced and broken it shorting it out. There was a little heat mark on the south-bridge.

[Toasty]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Ummm....?

How do you get answer 1 with answer 2...?

-or-

Is the answer to the PSU question the reason the mobo isn't posting?

In that case you have a short on the mobo.

.

[c_hegge]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

I'd try new caps. I made the same mistake on an ASUS board once. It only ran for a second, but that was all it took to kill the pannies I recapped it with. They had started to bulge and I realised my mistake.

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

Ummm....?

How do you get answer 1 with answer 2...?

-or-

Is the answer to the PSU question the reason the mobo isn't posting?

In that case you have a short on the mobo.

I assumed the two questions were asking a different questions. My answers as I understood the questions are not contradictory. I just misunderstood the question(s).
Answer to Question 1: All the voltages on my PSU tester showed correct values.
Answer to Question 2: When I attempt to turn on the computer the PSU does nothing, (it is not running) and neither does the motherboard.

It does sound like a short in the motherboard though. There are no solder bridges, splash, or any signs of any issues on the surface of the board. I inspected it with a magnifying glass. Do you have any ideas as to what could have lead I mean led to the short. Is there something I could have done to cause a short? I would like to avoid any process issues on any further projects. I appreciate your help. Thank you very much.

[ladalet]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

I'd try new caps. I made the same mistake on an ASUS board once. It only ran for a second, but that was all it took to kill the pannies I recapped it with. They had started to bulge and I realised my mistake.

As I stated in my post, I did install new caps to replace the ones installed backwards and that fixed the problem. The motherboard posted. The problem now is that I changed a different group of caps, installed them correctly, and the motherboard would no longer post. I put the old caps back in and it still will not post. Thanks

[c_hegge]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

ah, whoops, I missed that bit. Check for any solder blobs that could be shorting something.

[Uranium-235]

Re: New Caps on ASROCK K8 Upgrade 760GX quit working

I'm suprised the reversed caps didn't pop and fizzle. sometimes its better to leave well enough alone