First post, by Kahenraz
I purchased a GeForce 4 Ti 4200 from eBay which appeared to be in fair condition but was "untested" which usually means broken. Oh, my was it broken. The look of the card is unimposing when photographed but there is more here than what can be seen from a cursory inspection.
The heatsink assembly is not just dusty but caked with thick and chunky dust bunnies. There must have been some kind of moisture because the fan itself was rusted and seized, unable to spin not just from the dust but due to internal resistance or a failure of the armature windings. The hair-fine tail end of the windings that connected the DC motor to the PCB for the fan were corroded which weakened the exposed connections enough to break prior to or during disassembly. This required the motor itself to be taken apart for careful cleaning to try and repair it.
On the back of the PCB of the video board itself there were also two missing 0402 (very tiny 1.0mm x 0.5mm size) capacitors directly beneath the GPU. An inspection under a microscope showed several other capacitors in the same area as well as others that were cracked or damaged. Many of them needed only a light touch with tweezers to crumble. I ended up removing 12 of these capacitors in total. It's possible that some were not actually bad but is difficult to confirm visually so I erred on the size of caution. It takes a long time to remove, prepare, replace, clean, and test, and it's much easier to replace more of these than necessary all at once.
Unfortunately, I didn't take any photos of the repair of the DC motor or its internals since it was such a tedious and gruesome repair and I wasn't expecting to succeed. I did however take one photo with the fan removed after I found that it was still inoperable after a clean and a soak; this is why it appears wet in the photo.
The photos of the missing capacitors were as received. The photos of the crumbling capacitors are a result of pressing on them lightly with fine tweezers. There was no damage to any of the pads.
I did manage to successfully repair the fan and it is whisper-quiet. I was able to clean it and reattach the severed armature windings to the PCB. The moto shaft required careful cleaning and lubrication and the heatsink itself endured several extended baths in vinegar (5% acidity) with repeated scrubbing to remove oxidation and wear to the surface. Some of the screws had rusted or stripped and required a light oil to remove. I did not have a matching replacement with the only difference being that the heads of the screws are a bit larger now.
The final photo is a quick shot of the heatsink being held on for a beauty shot. The video board itself still needs to be repaired at this point.