Ah, the Trio3D! Have this card, too. It's a first gen AGP card and a nice collector's item (its the last of the Trio/ViRGE line).
Think about it like a 66MHz PCI card with an AGP pinout.
Maybe it doesn't work for you because yours is an AGP2x card and requires a higher voltage.
If you plug it into a newer mainboard with an AGP4x or AGP8x slot, it maybe doesn't work. No harm is caused, though.
But if you think its broken and you want to fix it, replacing the voltage regulator is a first step (or is this a 2N3055 pass transistor ? Can't see).
That's just an idea, though. Judging by the photo it looks fine. There are no signs of overheating; it's not bronze coloured.
But that doesn't have to mean anything. I've had got broken voltage regulators that appeared to be fine.
Btw, I do have the older AGP1x model without that black little thing in the upper-left corner. 😀

Here is some information about the Trio3D:
http://old.vgamuseum.info/component/content/a … s3-trio-3d.html
http://www.vgamuseum.info/index.php/component … rio3d-2x-86c368
http://vintage3d.org/trio3d.php

The black component has text "75307D" and seems to be some transistor. I'm not so into electronics so don't recognize every component.

First of all, have you tried the card on another motherboard? Long shot but it's a fact that early AGP motherboards and early AGP cards were sometimes a bit picky. Not just a motherboard with a universal AGP slot, one that clearly has the notch for these cards in place.

Sorry, haven't thought of that. Now you're saying it, I remember old AGP devices were quite troublesome.
@markot You're right, it's a transistor (a MOSFET). They're pretty much tough, so maybe the cause is something different.

I have tried this card on 2 or 3 different motherboards. Same problem on each of them, so I suspect there is something wrong with this card.

Try to clean the gold fingers with a rubber.

Add a working PCI card and boot some appropriate Linux live CD. Use the lspci command to check if the dead card shows as PCI device. If it has an appropriate PCI ID there may be a problem with the video BIOS. You can dump the video ROM using this manual: http://etherboot.org/wiki/romdumping

If it doesn't show properly the about last chances (beside looking for damaged traces or components) would be to resolder the chip and replace the crystal.

The contacts are all clean and in good condition, so cleaning the contacts would not help. The overall condition looks very good, so I must find more information from different places before I start to desolder anything.

I've had it at least once that the contacts looked clean but cleaning helpend nevertheless...

h-a-l-9000 wrote:

I've had it at least once that the contacts looked clean but cleaning helpend nevertheless...

Ok, I will try it at least.