So I got this HD 4850 512MB version for free and I was hoping to get it up and running. Well easier said than done. At first the card wouldn't power on (black screen). I pressed down on the gpu and it showed life, sorta. There were lines all over the screen. After I restarted the PC it gave me a black screen again. So after seeing that it powered up after pressing on the gpu I decided to reflow it. I reflowed the gpu at about 185-195C for 1:30, then 195-205C for 45s, 215-220C for 15s and 230-235C for 15s. My thermal probe decided not to work, and I didn't have an other thermal probe at the time (nor did I have flux), so I used the infrared thermal sensor. Which isn't as accurate as it should be, and it changes the readings depending on the angle, so I didn't dare to heat the for more than 15s at 230, for all I know it might be 240C or more.
The card started working (sorta) everytime I turned on the PC. There still where lines, but after post and in windows there where only a few barely visible vertical thick lines (blue if anyone wants to know). I get a BSOD when installing the drivers, which isn't surprising. I reflowed it again, trying to get the keep it over 210 most of the time. Again almost same result. The lines where gone... but there where dots. After a second the lines where back.
I came to the conclusion that the card started after pressing on it because it is bent (probably because of a repair done by someone else, or just heat) and the ram chips are also affected when I press on the gpu.
I reflowed the ram with flux and a thermal probe, but I couldn't keep the temps over 215C for more than 45s and at 230 for 10s as I was holing the thermal probe with my hand and I was afraid that I might push one of the chips. The lines at post are gone, but there still are dots (white and green, as seen it the pics below) and the thick lines after post.
So now I want to do a proper reflow, and I am not sure about the temps and times, as ram chips have always been hard for me. I am not sure whether they are just harder to heat up or have a lower thermal conductivity level and my probes are getting the right readings.
P.S. I found an SMD that was ripped of the board, but I resoldered it and that didn't fix anything, it probably go damaged during installation or handling.
Also the pcb is pretty bent.
And as for equipment that I am using:
A heat gun (with a potentiometer).
A stove for preheating.
A digital thermometer (a high quality industrial one, but I'll have to post the model later as I am not at home and I don't remember it).
I'll post a picture of the card on the "preheater" later on today.
Any ideas and recommendations are welcome!
The card started working (sorta) everytime I turned on the PC. There still where lines, but after post and in windows there where only a few barely visible vertical thick lines (blue if anyone wants to know). I get a BSOD when installing the drivers, which isn't surprising. I reflowed it again, trying to get the keep it over 210 most of the time. Again almost same result. The lines where gone... but there where dots. After a second the lines where back.
I came to the conclusion that the card started after pressing on it because it is bent (probably because of a repair done by someone else, or just heat) and the ram chips are also affected when I press on the gpu.
I reflowed the ram with flux and a thermal probe, but I couldn't keep the temps over 215C for more than 45s and at 230 for 10s as I was holing the thermal probe with my hand and I was afraid that I might push one of the chips. The lines at post are gone, but there still are dots (white and green, as seen it the pics below) and the thick lines after post.
So now I want to do a proper reflow, and I am not sure about the temps and times, as ram chips have always been hard for me. I am not sure whether they are just harder to heat up or have a lower thermal conductivity level and my probes are getting the right readings.
P.S. I found an SMD that was ripped of the board, but I resoldered it and that didn't fix anything, it probably go damaged during installation or handling.
Also the pcb is pretty bent.
And as for equipment that I am using:
A heat gun (with a potentiometer).
A stove for preheating.
A digital thermometer (a high quality industrial one, but I'll have to post the model later as I am not at home and I don't remember it).
I'll post a picture of the card on the "preheater" later on today.
Any ideas and recommendations are welcome!
Attached Files
Comment