SGI: Hardware

I just did (another) something really, really stupid....

I was running my 1600sw connected to a DVI port on a PC, via a PIXSolution adapter... Everything worked great...

Yesterday I was fiddling about inside the PC while it was on (stupid, I know...) and accidentally shorted something on the graphics card, killing the DVI out. Swapped in another graphics card and everything on the 1600sw was red... I really mean everything - what was supposed to be black was red and everything that wasn't supposed to be red was just a lighter shade of red. After a while the 1600sw started making a buzzing sound and the image appeared ghosted.

I have a multilink adapter aswell, so I tried that in analog mode - that seemed to work. This morning I connected the Multilink, without input connected, mashed a few buttons on it and it switched into 'diagnostic mode'. It showed all tests as 'passed' except "Backlight" and something along the lines of "Main Logic" - does the latter refer to the MLA itself or the 1600sw?

I plugged a (different) DVI cable into the MLA, powered up and got a reasonable output , until the resolution went above that of the PC's POST screen when all I got was graphical corruption... And still the 1600sw is buzzing.

So, I went from a working graphics card, 1600sw, Pix-link and MLA to a broken graphics card, maybe broken 1600sw, maybe broken MLA and broken Pix-Link. It's the last of those I'm most bothered about - the 1600sw is relatively more replaceable and the Pix-Link box I much prefer to SGI's bulky MLA. It seems to work properly aswell, all the scaling functions etc. - it's just this bloody (excuse the pun) redness. I've opened it up and nothing seems burnt, even poked around a bit with a multimeter, but it's seriously needle in haystack territory, and I know nothing about electronics .

Also, this wan't all as clumsy and neanderthal as it sounds - honest

For starters, sounds like you cooked your PixLink.
Secondary, do you have your system set to run a madly high resolution?

Did you try another graphic card, or at least try the other DVI plug on your graphic card? The good news is, PC graphic cards are pretty much disposable nowadays. Take a look around the DVI transmitters on your graphic card (you might have to pull off a fan but if you shorted something accidentally I don't think this is the case)

Well I've got it working through the original graphics card, VGA through the multilink. DVI on the card is completely dead with no sign of visible damage. (EDIT: I did try another graphics card; that's how I'm aware of the problems on the Pix-Link). I'd still prefer to be using the Pix-Link though, just running around it with a multimeter and trying to test all the caps and resistors.

There's 2 EEPROMs on the board - one near the temp/backlight controls that I assume is used merely to save those settings, and one near the DVI connector - any idea what data that would hold? I might try sticking a blank EEPROM in that socket and see if that works as a 'reset'.

The main processing seems to be done by a Silicon Image Sil859CT100 chip, for which I can't seem to find a dastasheet. That in turn feeds into 2 National Semi DS90C383A LVDS transmitters (two I assume because they only support upto SXGA according to the datasheet). There's also a PIC onboard, along with what I assume is a JTAG connector to program it - I sure hope that isn't fried because I'm not going to be able to find firmware for it!

It seems that all pixels are stuck to 100% red - green and blue seem to work as normal because whites do appear as white. I'm hoping it's just a bad capacitor or resistor - I've checked the ones that lead to the R, G and B inputs of the LVDS chips and they seem fine but bear in mind this is with a bog-standard multimeter, not a capacitance meter, and that I didn't remove the caps from the board so it doesn't mean much.

Really would hate to lose the Pix-Link, it's a beautifully engineered bit of kit, down to the details. The way the layers of the PCB are numbered is simply brilliant.

EDIT: Oh, and thanks for your help guys. Is anyone here knowledgeable in electronics? If I upload some PCB pictures, would anyone be able to point me into the right direction as to which components the 'Red' signals are likely to be travelling through?

EDIT: Ah, found out from here that the Silicon Image chip may actually be purely for scaling - http://pocdesigns.com/oim_designs.htm

I believe the PixLink guy is still in business. Now that you've determined it's not something simple like a fuse, it would probably be cheaper and certainly more reliable to have them repair the card.

Ah, thanks for letting me know. Their site redirects to the personal website of the engineer, who I assume you mean is 'that guy'. I'll shoot off an email.