Palit HD Radeon 4850 - OvenTrick and Recap

[alucard_t2]

Hello,

I need some help with the above mentioned graphics card. Bought it defective because it was "almost" dirt cheap. The card gets power but doesn't give a signal, either digital or analog. Will attempt to do the oven trick. Already worked on an 8500GT, temps in my oven are between 200°C at medium flame and 230°C at max(I don't have the gas marks on the knob).
I tooks the caps off(I would never put the board in the oven with the caps on), checked the capacitance and ESR, and have become somewhat concerned.
These are the PSC polymer series from NipponChemicon, 820u@2.5v and 270u@16v

The tolerance is still within the 20% tolerance but the ESR has gone a little up.
The first one has gotten to 36-40mOhms from 5mOhms as specified by the datasheet, and the second, 65-70mOhms, up from 11mOhms. Don't know if it was THAT low when they were new, even if they're polys.
Should I put these back or change them, might get my paws on some FMs from Panasonic, but these have higher ESR and lower ripple current rating. How much does ripple current in caps matter on video cards?

[sam_sam_sam]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

If this graphics card has a lot of use and is an model that has been out for a while and you are getting a some what higher ESR reading

"The tolerance is still within the 20% tolerance" are you talking about uf reading if it very near the or over - 20 % or way over the + 20%
you will find that ESR value will change allot when you first read them the reading will be high and after just holding them in your hand a minute or two you will see the value go down almost to value that it should be

If this is the case these are BAD

I would change them all

[alucard_t2]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

I kept them. I didn't have time to check them thoroughly because the measuring tweezers weren't mine and they're also not great, so not sure about the readings. The card works and the temps are awesome, 35°C idle and 60°C under load. The only problem is this card is an animal. Might need a better power source(using two molex's to power the 6pin pci-e piehole)

the tolerance is within the tolerance)I know. The mosfets are from STMicro, but I think the card will make it known far and wide, if its caps are failing.

Since this is a general discusion, do you think it's a problem that the card is slightly bent because of the cooling system. It's actually a clearly visible bending where the heatsink meets the board. I think it might hurt the GPU, since the board underneath it is not flat The heatsink is crappy, big and heavy, but crappy nontheless. Might try using some 1mm or 2mm spacers on the heatsink screwholes.

[momaka]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

Since this is a general discusion, do you think it's a problem that the card is slightly bent because of the cooling system.

Yes. This is a big part of what caused so many of the original Xbox 360s to fail (the other part was the high GPU temperatures, which with many ON-OFF cycles would crack the BGA joints).

[alucard_t2]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

I think I just screwed it up
I overheated it and the laquer on the board is raised a bit.
Also the coating on the GPU, very small area, like it's got a tiny air bubble underneath. What have my grubby lill hands done((((((((
Can someone please look at the pics and give me good news?
I'll be waiting with a gun at my head...

[momaka]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

That's de-lamination. Happens when you apply too much heat too quickly (usually due to moisture trapped between the PCB layers). Unfortunately, there isn't anything you can do. Both the board and the GPU are done for .

If you do occasional motherboard and/or video card repairs, keep the card for its SMD components.

Also, if you do an over reflow next time, make sure to keep the board/card in there for for a good 10 minutes on low heat (around 100C) so that any moisture can dry out. Then after that, slowly bump the temperature up to 230C. 1 to 2 steps should be okay - first bump up to 150-170 and leave for a few (2-3) minutes, then set to 200C and leave again for a few minutes. Finally, set to 230C, leave for another few minutes, then turn off the oven, and slowly let it cool down.

[alucard_t2]

Re: Palit HD Radeon 4850 - OvenTrick and Recap


You can imagine the demons I'm conjuring right now
Should I even try it, or is it useless?
Oh well, at least the caps are good and the cooling system is sweet..
Might try it on an older 4850 I had. Using the backside "X" retention from the bubbly one, maybe I could keep the older "sort of" good board from bending. The old board works, but I have to reset the comp 3-5 times till it posts, after that it's all good. Unfortunately, powerful video cards are addictive. I got a taste of the power and now I want more

[momaka]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

Should I even try it, or is it useless?

If you have another spare motherboard you don't mind experimenting with, then you can try the video card on that. Technically, nothing bad *should* happen, but I rather be safe that sorry in the rare case that it does.

The old board works, but I have to reset the comp 3-5 times till it posts, after that it's all good.

Check your power supply and motherboard for bad capacitors. I've seen this issue happen a few times due to that.

Unfortunately, powerful video cards are addictive.

They are indeed. A few months ago, I had an older computer (now semi-dead) that had a Radeon 9700 video card in it. Despite the video card being so old, it still kicked major ass compared to some newer on-board video cards. When that computer started crashing and I couldn't use it anymore, it felt really weird going back to a PC with a less-capable video card.

[alucard_t2]

Re: Palit HD Radeon 4850 - OvenTrick and Recap

That's a negatory. Both mommyboard and PSU are crystal.
I work in an EMS facility here in Romania.
I'm an engineer, and yes, I still f-ed it, and yes, you may fire at will.
I could try taking the card to the X-ray machine to see if the traces are interrupted but the manager will have my head on a plate replete with silicon dressing, if he sees me.
Will let you know if I revive Frankenboard.