VOGONS


First post, by Kahenraz

User metadata
Rank l33t
Rank
l33t

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.

ebay_4200.jpg
Filename
ebay_4200.jpg
File size
362.65 KiB
Views
599 views
File license
CC-BY-4.0
IMG_20211211_044815.jpg
Filename
IMG_20211211_044815.jpg
File size
473.67 KiB
Views
599 views
File license
CC-BY-4.0
IMG_20211211_044745.jpg
Filename
IMG_20211211_044745.jpg
File size
290.45 KiB
Views
599 views
File license
CC-BY-4.0
IMG_20211123_214910_resize_36.jpg
Filename
IMG_20211123_214910_resize_36.jpg
File size
223.17 KiB
Views
577 views
File license
CC-BY-4.0
IMG_20211123_214851_resize_79.jpg
Filename
IMG_20211123_214851_resize_79.jpg
File size
548.03 KiB
Views
577 views
File license
CC-BY-4.0
Last edited by Kahenraz on 2021-12-12, 02:33. Edited 5 times in total.

Reply 1 of 6, by Kahenraz

User metadata
Rank l33t
Rank
l33t

Photos of the SMD capacitors on the underside of the board, directly beneath the GPU. These are all 0.1nf (100pf) 0402 SMD ceramic capacitors.

The last photo is with all of the capacitors removed and the surface cleaned and prepped. There are 24 pads for 12 capacitors (2 pads per capacitor).

IMG_20211211_044921.jpg
Filename
IMG_20211211_044921.jpg
File size
121.32 KiB
Views
590 views
File license
CC-BY-4.0
2021-11-11 23_23_06.png
Filename
2021-11-11 23_23_06.png
File size
446.8 KiB
Views
590 views
File license
CC-BY-4.0
IMG_20211123_215003_resize_7.jpg
Filename
IMG_20211123_215003_resize_7.jpg
File size
315.94 KiB
Views
590 views
File license
CC-BY-4.0
IMG_20211123_215021_resize_51.jpg
Filename
IMG_20211123_215021_resize_51.jpg
File size
305.57 KiB
Views
590 views
File license
CC-BY-4.0
IMG_20211211_045122.jpg
Filename
IMG_20211211_045122.jpg
File size
687.98 KiB
Views
590 views
File license
CC-BY-4.0
Last edited by Kahenraz on 2021-12-12, 01:59. Edited 3 times in total.

Reply 2 of 6, by Kahenraz

User metadata
Rank l33t
Rank
l33t

The repair was done with solder paste and a hot air station. I think this could have been done with less solder paste but the tip of my syringe is large compared to the size of these pads and it was very difficult to control how much was deposited. I went back and carefully sculpted each little mound of solder paste to try and mitigate how much excess was deposited.

I found heating the paste and melting it to be extremely difficult even when bringing the temperature up to 400 degrees C due to the large copper ground plane. I also had much more trouble this time than I did working on it previously simply due to the change in temperature as a result of the weather; I seriously thought that my soldering iron was broken because of how difficult it was to manage the temperature of this board. I really need a pre-heater for these large multi-layer boards.

I've also included a photo with my thumb next to the component area for a sense of scale. These things are VERY small!

I spent several weeks on this repair as a result of careful planning and repair as well as having to wait for parts (the capacitors) and practicing for the right technique. All of this planning and on the day of repair I still learned something new and surprising; even a slight change in ambient temperature can have an impressive affect on soldering. Now I understand how important a pre-heater is for certain kinds of repair. I wasn't sure if I could repair this when I started but I knew that I had the tools and could build the experience I lacked.

When the repair was complete I plugged it in and was casually greeted by the video BIOS. No smoke. No flames. It works. 😀

IMG_20211211_040621_resize_20.jpg
Filename
IMG_20211211_040621_resize_20.jpg
File size
547.38 KiB
Views
582 views
File license
CC-BY-4.0
IMG_20211211_035857_resize_28.jpg
Filename
IMG_20211211_035857_resize_28.jpg
File size
594.77 KiB
Views
582 views
File license
CC-BY-4.0
IMG_20211211_045141.jpg
Filename
IMG_20211211_045141.jpg
File size
388.12 KiB
Views
565 views
File license
CC-BY-4.0
IMG_20211211_042849_resize_97.jpg
Filename
IMG_20211211_042849_resize_97.jpg
File size
917.37 KiB
Views
582 views
File license
CC-BY-4.0
IMG_20211211_042951_resize_97.jpg
Filename
IMG_20211211_042951_resize_97.jpg
File size
407.89 KiB
Views
570 views
File license
CC-BY-4.0
Last edited by Kahenraz on 2021-12-12, 11:42. Edited 4 times in total.

Reply 3 of 6, by Kahenraz

User metadata
Rank l33t
Rank
l33t

This has been a fun an exciting repair. There are a few minor things to address: I have the correct screws for the heatsink on order and the plastic posts to secure the heatsink to the video board were very brittle and broke during removal, so I will need to replace those as well to put it all back together.

I will post some additional photos here when I have everything completed.

I have several more repairs in-progress and this is the first SMD repair of many. See these other threads for my other in-progress repairs of NVIDIA GeForce FX 5900 and 5900 Ultras.

NVIDIA GeForce FX 5900 triage and repair
NVIDIA GeForce FX 5900 Ultra triage and repair
I won a very nice looking GeForce FX 5900 Ultra with a stock cooler from eBay

Reply 4 of 6, by Repo Man11

User metadata
Rank Oldbie
Rank
Oldbie

Impressive work. I've had good luck replacing full size electrolytic capacitors on various computer components, but those tiny ones would be beyond my capability.

"A lot of times when you first start out on a project you think, This is never going to be finished. But then it is, and you think, Wow, it wasn't even worth it." - Jack Handey

Reply 5 of 6, by aaronkatrini

User metadata
Rank Member
Rank
Member

I enjoyed reading how you managed to fix the card. The GF4 Ti 4200 is quite an interesting card for Win98. It has good compatibility, good performance and it can still be found for a reasonable price.

Reply 6 of 6, by subnet_zero

User metadata
Rank Newbie
Rank
Newbie

Wow, impressive repair job with those tiny resistors. What microscope did you use for this?
I'm also very impressed by the repair job of that fan. Somehow the few fans from that era I tried to repair could not be disassembled at all. 😑