I did say that I didn't see anything visible wrong with the board but this isn't entirely correct... at least nothing serious and not at first. A close inspection under a microscope revealed some minor damage to a resistor in the bottom corner. Measuring it with my probe suggested that there was a connection, but I removed it and applied some fresh solder for a more solid connection just in case. This first repair did not solve any of the problems, as expected.

My next attempt was to clean and apply fresh solder to all three large packages of the graphics processing chips that make up the Voodoo 2. This required a liberal amount of flux, a steady hand, and a lot of tedious work to ensure that there were no solder bridges among the hundreds of tiny pins. I reflowed the solder on one chip at a time only, cleaned, and tested the card to ensure a consistent baseline and to monitor for any changes.

Despite my best efforts, I did miss some bridges despite careful and repeated inspection. I was very lucky that this did not damage anything and only resulted in some texture artifacting. It's very disturbing to try and perform a repair and find that things have gotten worse! Because I was careful to reflow one chip at a time, I knew where to look for the problem. This part was very important because if I had reflowed all three chips at once and there was a problem, I wouldn't know with which chip it originated.

I failed to take a photo of the legs of the chips prior to working on them so it's difficult to properly convey the original state of these chips and the extent of oxidation. I've instead provided two photos where one is focused on the top of the leg which is still oxidized and the bottom which is shiny and clean. Note that the surface at the top of the leg is still visibly oxidized and dull even after having be cleaned and scrubbed several times with isopropyl alcohol and mild dish soap. The only way to properly deal with this is to use a solvent to clean the surface such as vinegar or activated flux.

Note that it is NOT necessary to remove this oxidation as a means of preventative maintenance. Oxidation will occur on the surface of most metals and, as long as it is not disturbed, will provide a protective barrier for the rest of the material beneath it. Even if it were to be removed the cleaned surface would quickly oxidize again without some kind of protective layer. This oxidation is otherwise benign. Corrosion is the true enemy as it can easily penetrate deep below the surface.

I reflowed the southernmost chip first, the PPU also known as the PixelFX (500-0009-01) without success. I then reflowed the easternmost chip, one of two TMUs on a Voodoo 2 known as the TexelFX (500-0010-01) and the card sprung back to life! I ran several tests and had no issues with games, card detection, or corruption.

Due to the time consumed with preparation and testing as well as the fact that all three chips exhibited the same amount of oxidation and poor contact with their pads, I decided to reflow the westernmost chip as well, the second of the two TMUs. It's very time consuming to perform these repairs and to clean the boards afterwards so it made sense to reflow the last chip at this time.

Repair complete! This Voodoo 2 has been saved and is otherwise in excellent condition and has a new lease on life.

Hi,
thanks for this report! Very helpful with diagnozing faulty cards.
What type of flux did you use and how do you clean the card after reflow work?
I tend to have flux remaining behind the pins where it can't be removed that easily. That's really annoying.

Rather easy to clean flux depends on what you pick the flux. I preferred no-clean flux and geniune 559 is my favorite but they tend to get real old and takes lot of cleaning if using soldering iron. I tried other synthetic fluxes by Amtech and they are so easy to clean up.

But 559 is real good for hot air work.

In other words, try synthetic flux types from reputable brands if using soldering iron.

Cheers,

https://www.voodooalert.de/board/forum/index. … deren-ursachen/
Just wanted to inform people that there is a german guy who is very experienced in fixing any kind of 3dfx cards. English is no problem. If you need help you should write him a message!
Username: Backfire

Good job!

Recently did some chip work. Quickly learned line it up perfectly, get some pads stuck, then With tweezers push down on the chip and run around it with hot air, inspect with microscope and clean off flux paste then go around it with microscope again and a needle and push the pins sideways, any that move need another go

It’s amazing how easy it gets with good flux and hot air. Trying to do this with a iron is the hard way. And most likely a worse result.

ChrisK wrote on 2021-12-25, 13:57:

What type of flux did you use and how do you clean the card after reflow work?

ChipQuik SMD29130CC No-Clean Tack Flux. This is the most amazing flux I have ever used. It's amazing.

It cleans very easily with simple rubbing alcohol but requires some mechanical encouragement to do so. When it gets stuck or blown under a chip or otherwise out of reach then it's not easily removed. I would suspect that it would clean well in a high quality sonic cleaner but I don't have one to verify. It's a no-clean flux so leaving traces on the board won't damage anything.