ATI 9800 Pro 128MB

[Per Hansson]

Hi, got this in from a malfunctioning Dell PC

The GPU fan has failed miserably, the wires are stiff likey they where in a fire and the whole fan has melted away from the heatsink, including desoldered the power cables!!!

Anyway, two caps have bulged completely, both top and bottom, I suspect it is due to the fact that the card became hot enough to melt solder and plastic!!! (Those caps are 10x13mm)

All caps read 0.00 ESR when installed on the board, except for the 3 tiny ones on a row alone close to the AGP connector (they are normal, 0.1 ESR)

Are these normal electrolyte caps or are they solid caps? I.e. should I use normal electroytics or Sanyo OS-CON if I want to recap it?

(I have another 9800 Pro that works and I checked the ESR on it's caps which I could reach and they where all in normal ranges...)

[kc8adu]

Re: ATI 9800 Pro 128MB

the vented ones are lytics.
they may be bypassed with tantalum or mlcc so esr reads ok even if they are open.
then again gpu could have a shorted core too.
replace caps and cross fingers.

[Big Pope]

Re: ATI 9800 Pro 128MB

470uF 10V are Nichicon HC series, i always see those caps at Radeon 8500 and i will replaced with 1500uF 6.3v/10v D10x16mm ultra low ESR caps(i.e. Samxon GC), size is fit well and works fine.

I also saw similar caps Nichicon HD series on Abit baords, i.e. KG7.....

[Per Hansson]

Re: ATI 9800 Pro 128MB

kc8adu; does not ESR of 0.00 mean the cap is shorted?

On my fully working 9800 Pro (exact same layout) the caps had ESR between 0.04 and up...

The card does work, comp does post, however screen is totally garbaged, but I can see the DELL logo and so on... Put my own 9800 in it and it started just fine...

[Per Hansson]

Re: ATI 9800 Pro 128MB

Swapped out the two bulging caps for Samxon 1500uF 6.3v GC caps

Screen output was still just as garbaged as before the cap change...

This was also the hands down most difficult recap job I've ever done, PCB is 8 layer so it is very thick, and good at transferring heat away...

[dood]

Re: ATI 9800 Pro 128MB

Sounds like that core is permanently cooked. By the looks of it, rightfully so.

[Per Hansson]

Re: ATI 9800 Pro 128MB

Yea, if you look at the pic of the whole card the picture looks like the camera messed up the colors, it really didn't

The whole PCB has changed color to a much darker red, I also took the heatsink off, the paste was like stone, had to use a razor to get it off, unlike anything I've ever seen (no, it's not a pad, just thermal paste that has been exposed to extreme temps)

The resistors and stuff on the backside of the GPU are also in a very different color, yellow like, and the GPU package itself, it's supposed to be green, it's closer to black than green...

Yay, I think something got hot, of course the fan was 100% blocked by a SB Live card in the slot right to it, when there was 2 free slots below, sigh!

And another interesting note, the whole computer was covered in dust which I blew out with compressed air, however the GPU heatsink looked like new, no dust at all, you do the math...