Discolored output when using DVI to VGA adapter on 6800 Ultra. \ VOGONS

Discolored output when using DVI to VGA adapter on 6800 Ultra.

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First post, by Ozzuneoj

Posted on 2018-02-04, 05:29

Ozzuneoj Offline

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I've personally never seen a problem like this and Google searches are turning up nothing. I recently obtained an eVGA 6800 Ultra AGP and the card works beautifully but using DVI to VGA adapters results in severely discolored output. It isn't a software issue as the discoloration starts as soon as the monitor turns on after POST. Using a DVI cable produces a flawless picture.

The card has two DVI-I outputs. Strangely, if I use the adapter on one DVI output the image appears to have no blue (it is very greenish yellow) and if I use the other DVI output it has no red (it is very blue). I've tried a couple DVI to VGA adapters on an LCD and a CRT. The LCD looks great on the same card with a DVI cable.

System specs:
Abit NF7-S 2.0, Athlon XP 1700+ at 2Ghz, 2GB DDR 400, WinXP, 80GB Maxtor ATA-133, Seasonic 550HT power supply (80plus rated, 30a on +5v, 4 good 12v rails). I tried a BFG 6800 GS on the same system and it works perfectly with the same monitors and adapters over VGA.

Anyone have any ideas as to what would cause this? I've only ever seen a bad monitor or loose cable do this. Is it likely that something is fried on the card? Thinking about it now, I'm wondering if there's physical damage to the analog pins in the DVI ports but it seems unlikely that both would be damaged.

EDIT: Ended up being a couple of broken SMD filter inductors which were easy to repair... see this post: Re: Discolored output when using DVI to VGA adapter on 6800 Ultra.

Last edited by Ozzuneoj on 2018-02-04, 21:37. Edited 2 times in total.

Now for some blitting from the back buffer.

Reply 1 of 5, by Ozzuneoj

Posted on 2018-02-04, 19:49

Ozzuneoj Offline

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Well, crap, I figured out the problem...

Two broken tiny SMD components on the traces leading to the VGA pins on the DVI-I connectors... one from each connector.

L515 and L514. I believe they are inductors? These look like they'd be incredibly hard to replace... four TINY legs on each one. Definitely not something that could be done with a soldering iron.

Anyone have any idea if there's any way to know what values these would have and if there's a somewhat realistic fix possible? I have a hot air gun but I've never even used it and its a cheap one from Radio Shack (single temp) so I doubt it'd be a good idea for me to attempt a repair like this with an otherwise working card.

I'll be honest, I was mainly interested in selling the card since I have a 6800GT that would suit me fine for one of my later AGP systems. I'm sure the vast majority of people out there would just use an LCD equipped with DVI on a card like this anyway, but still, having both VGA ports messed up has to hurt the value a bit.

Is there any possibility that an inductor in these locations is "unimportant" and could just be jumped with a wire? I've heard of people doing this with other components but my understanding of complex circuits like this is quite low.

EDIT: Sadly the pictures are gone from this thread but I see mention here of the inductors just being "filters" that are bypassed with no side effects.
Lost my Green Signal - How to repair a VGA out?

Now for some blitting from the back buffer.

Reply 2 of 5, by 133MHz

Posted on 2018-02-04, 20:48

133MHz Offline

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Can confirm that you can just bridge these final inductors on the analog RGB lines and it'll give you the color back with no ill effects.
Looking at the pictures seems that you only have to bridge the two adjacent pins closer to the DVI connectors, like this:

1[ ] [ ]
2|     |
3[x]-[x]
4 L51x

The topmost two pins seem to connect to the ground plane. Please check with a multimeter if possible.

http://133FSB.wordpress.com

Reply 3 of 5, by Ozzuneoj

Posted on 2018-02-04, 21:05

Ozzuneoj Offline

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133MHz wrote:
Can confirm that you can just bridge these final inductors on the analog RGB lines and it'll give you the color back with no ill […]
Show full quote
Can confirm that you can just bridge these final inductors on the analog RGB lines and it'll give you the color back with no ill effects.
Looking at the pictures seems that you only have to bridge the two adjacent pins closer to the DVI connectors, like this:
1[ ] [ ]
2|     |
3[x]-[x]
4 L51x
The topmost two pins seem to connect to the ground plane. Please check with a multimeter if possible.

Thanks! I actually just did this right before you posted and tested it with a multimeter. I checked the other ones that were still intact. It ended up being the two right side pins that were supposed to be bridged. Like this:

1[ ] [x]
2|     |
3[ ]-[x]
4 L51x

I got bold and decided to just do it. It was fairly easy to bridge the pins with solder and it completely fixed the problem! A surprisingly easy fix. 😀

The attachment IMG_20180204_151152 (1536x2048).jpg is no longer available

I'm going to cover these connections with some clear nail polish to protect them.