Geforce 6800gt VGA missing red output signal

[russianbot]

I have a Geforce 6800gt that is not outputting any red signal to the analog VGA connector, and everything is a shade of cyan. The card otherwise works fine, and I'm pretty sure the problem is caused by a torn off inductor next to the VGA connector. In the photos I uploaded there are two inductors L512 and L515, but L511 is missing.

Anyone know what inductor I can use to replace the missing one? The two remaining ones are about 2.1mm long, 1.2mm wide and 1.2mm tall. They seem to have two connectors on each end. What would be a suitable replacement that I can buy?

[R_J]

Re: Geforce 6800gt VGA missing red output signal

It might be one of these https://www.digikey.ca/products/en/f...=1&pageSize=25
If its on the vga output I doubt the value is that critical, anything around that size seems to be about 1µH

[russianbot]

Re: Geforce 6800gt VGA missing red output signal

Thanks, that's probably the one I'll order.

[momaka]

Re: Geforce 6800gt VGA missing red output signal

If bad comes to worse, you can just solder a piece of jumper wire across the inductor. It will work fine. I've done it before many times. Just might affect signal clarity at very high analog resolutions.

Note about your missing inductor above: it is a dual-inductor / common mode inductor. But really only one of the lanes (sides) caries the red output. So you only need to jumper that side - if using a jumper, that is.

[Uranium-235]

Re: Geforce 6800gt VGA missing red output signal

why not just use superior dvi

[momaka]

Re: Geforce 6800gt VGA missing red output signal

*tries to locate the DVI port on the back of the CRT monitor*
I don't think I have one!

[Topcat]

Re: Geforce 6800gt VGA missing red output signal

If bad comes to worse, you can just solder a piece of jumper wire across the inductor. It will work fine. I've done it before many times. Just might affect signal clarity at very high analog resolutions.

I was going to suggest that for testing purposes.

[Uranium-235]

Re: Geforce 6800gt VGA missing red output signal

you could also use a dvi-vga adapter if the port supports it

[momaka]

Re: Geforce 6800gt VGA missing red output signal

I was going to suggest that for testing purposes.

Well, that's what I did on my first card with that issue (a Radeon HD2400 XT). But then I found out that this "for testing purposes only" "temporary repair" was good enough for the analog resolutions I wanted to run (no ghosting or noise whatsoever). So I started "fixing" every card with this issue in this way... unless of course I had an exact replacement component from another card (which I do quite often, as I keep a good stash of dead GPUs.)

you could also use a dvi-vga adapter if the port supports it

Yup, or that.

It should support it. DVI (digital-only) ports became standard only on the Radeon RX series and GeForce GTX 10x0 series... and everything afterwards, of course, as modern GPUs no longer carry RAMDACs (save for some of the lower-end cards that may still come with a VGA port.)

But the 6800 GT is certainly old enough to support analog output through DVI.

[dj_ricoh]

Re: Geforce 6800gt VGA missing red output signal

Can you post a picture how it looks in curent state on the screen?

[japlytic]

Re: Geforce 6800gt VGA missing red output signal

I recommend replacing all three as a set for best performance - these inductors are typically used for electromagnetic compatibility.

[shabs1985]

Re: Geforce 6800gt VGA missing red output signal

I also have a 6800gt with the same no red on vga issue. did replacing the cap work?

[stj]

Re: Geforce 6800gt VGA missing red output signal

read the post again,
it's not a cap - he has an inductor missing because someone damaged it.

[shabs1985]

Re: Geforce 6800gt VGA missing red output signal

I have two inductors missing. how would you solder thesee back onto the board?

[momaka]

Re: Geforce 6800gt VGA missing red output signal

I have two inductors missing. how would you solder thesee back onto the board?

You'll need a soldering iron with a sharp tip. The tip doesn't necessarily need to be small. It just needs to be sharp. Chisel and bevel-shaped tips should be easier to use over regular conical/pencil. The one on my iron is spoon-shaped (cheap copper tip that wore into a spoon over time, but it works great for SMD stuff.)

As for the inductors... just put piece of wire in their place or a 0-Ohm SMD resistor. It's not an ideal solution (may or may not cause slight color imperfection or possibly noise/blurriness at very high resolutions), but it will get the card working, at least.

[stj]

Re: Geforce 6800gt VGA missing red output signal

hot air station.

[momaka]

Re: Geforce 6800gt VGA missing red output signal

^ Really? For SMDs with two leads only? Nah, I don't have the nerves for hot air for small stuff like that. Unless it's SMD with many (over 10) small pins, I don't bother with hot air. If you do hot air, then you need good flux and probably also solder paste, and a slew of other stuff. With iron, you just need flux and a steady hand.

[stj]

Re: Geforce 6800gt VGA missing red output signal

some gell-flux and hot air and the part will center itself on the pads,
i was recently changing some 0402 resistors like that!!

[momaka]

Re: Geforce 6800gt VGA missing red output signal

I suppose if the part is in an inconvenient spot, then hot air might be easier to use. I haven't encountered that too many times, though - at least not on video cards and motherboards. And I actually like doing those small 0402 SMDs with my iron - they are pretty easy. Helps to have long nails, though, (or good tweezers and a steady hand) as I often usually just keep the SMD on the board with my thumb nail, and then touch with the iron on one lead, then on the other. Takes maybe 1-3 minutes max to do everything. Hot air can be quick only if you have a good powerful station and you're working on a smaller board. The 852D+ I have takes way too long to solder anything, even on max heat, so I don't bother with it most of the time. It only comes out for QFN chips or similar work.

[stj]

Re: Geforce 6800gt VGA missing red output signal

i used an 858d,

the only real problem with 0402 is losing them when they ping off the end of the tweezers - just as well they come in long strips!