'Wobbling' video output to screen from Asus desktop mobo

[Triophile]

Hi guys.

I've done a search with a number of different sets of terms for this problem, but didn't really find what I was after (though I'm sure I can't be the only one to have witnessed this symptom).

On an ASUS P5LD2-TVM SE/S motherboard, with a couple of different PSUs, the video on the monitor 'wobbles'. It's noticeably worse with the onboard graphics than with a GFX card plugged into the PCIe slot. One PSU (an old Dell SFF unit) made the wobbling clearly worse, while a newer PSU almost eliminated it. Having lots of video movement on the screen seems to exacerbate the problem as well.

Basically, I'm assuming that, even though the caps on the mobo are not visibly bulging or leaking, some or many of them are duff. I'm also assuming the Dell PSU, even though its voltages measure well within spec, might be passing a fair amount of noise to its outputs. Is either of these assumptions likely to be correct?

Many thanks, Jon.

[Uranium-235]

Re: 'Wobbling' video output to screen from Asus desktop mobo

I could find VERY few pictures of this motherboard, but I did find one and from what I could tell three large caps behind the paralell port, if they have a 'tri' vent on them and are brown, they should be replaced. Those are United chemi-con KGZ's and those usually die without bloating

if you happen to see any others like this (brown with a tri-vent) on them of a decent size you should replace those too

as far as that PERTICULAR problem, sounds like some kind of interference/shielding problem. Not sure if its these caps that are causing the problems

[Scenic]

Re: 'Wobbling' video output to screen from Asus desktop mobo

From the few pics I found on google, there seem to be A LOT of junk chemicon KZG caps on this board, especially around the northbridge and some near the RAM slots and CPU VRM.

The ones on the pic are also well-cooked (sleeve peeled back, revealing more of the top metal than they should normally)
http://www.itpartsdirect.com/media/c.../image_512.jpg

Pics of your own board would help, as it seems that Asus shuffled cap brands around quite a lot on these. Another board pic I found (crappy quality) had no Panasonics (the stylized "T" vent on top) whatsoever, and KZG's instead of Rubycons on the VRM input (the 4 tall caps near the parallel port)

[mockingbird]

Re: 'Wobbling' video output to screen from Asus desktop mobo

I count 9 UCC TMZ/TMV caps on the CPU VRM that should be replaced, and I also see abunch of KZGs scattered throughout.

[Triophile]

Re: 'Wobbling' video output to screen from Asus desktop mobo

Apologies for the lack of pictures, remedied below. Thanks for the replies though - very helpful.

An overview:




Squat caps close to the CPU:




A handful of caps near the northbridge:




Not sure if these are linked to the PCI slots or the audio IC:




A few more near the southbridge:




The larger caps behind the parallel port:




Should I just replace every single cap on the board, or are most of the caps below about 330uF likely to be OK? The largest range I can find here in the UK seems to be Panasonic FCs on Farnell...

Cheers, Jon.

[Koda]

Re: 'Wobbling' video output to screen from Asus desktop mobo

Ok, before you go all ninja on that board try your monitor with another pc and the wobbly board with another monitor to make sure it's not the monitor or monitor cable that is creating the problem. Try flexing and moving the monitor cable during operation to see if that exacerbates the problem or if it changes the situation at all. If it turns out it is the motherboard at fault, try another power outlet preferably in another room in your house or apartment to rule out grounding problems. Try another set of VGA drivers. Try resetting the BIOS. Try running the PC with minimum components. Also try heating the capacitors with a hairdryer before starting the mobo and see if that improves the situation, heating the caps temporarily lowers the ESR, that might give you an indication as to what the problem might be (caps or not). If all of the above fails feel free to ninja the board as much as you like, you've got nothing to lose anyway.

Also what are those wires sticking out from the center right of the board? Try running the board without them, an intermittent short between those wires can also cause problems.

[Uranium-235]

Re: 'Wobbling' video output to screen from Asus desktop mobo

I would poly those tmz's and of course replace the KGZ's

[Triophile]

Re: 'Wobbling' video output to screen from Asus desktop mobo

The wires to the right of the mobo are the power supply cables of the IDE DOM (Disk On Module) plugged into the IDE socket. 8GBs of poor-man's SSD, with slow transfer speeds but zero noise and low power consumption ;-) They're terminated with a standard molex out-of-shot.

I'll have a go swapping stuff round. This board has already been with a few other components and OSes (currently Linux Mint 12, previously Tiny Core Linux), but by no means an exhaustive list. I'll try it with XP and some other gear before heating the iron.

Thanks again all :-)