Reflow.IT – Toshiba Satellite Pro P6100 with graphics memory errors

I had this Toshiba Satellite Pro P6100 laptop sitting around. It had been tested some time ago, and it had errors in the video graphics memory. I had used VMT which is a Video Memory Stress Tool, to run diagnostics on the video graphics memory .

SONY DSC

This is what the screen looks like. What we see at the top of the screen with the greenish lines are artifacts on the display due to these memory errors. Now the memory errors are not stable, they appear at different addresses and affect different bits, so it could be a graphics processor problem or a memory problem. This laptop had a separate card which contains the graphics processor and its two memory chips but also interfaces to the keyboard, mouse pointer buttons and the system board. Due to my previous success with using my SMD Rework station to reflow a laptop system board, I thought I should try this again.

SONY DSC

I removed the graphics add-on board, and taped up the areas that I did not want to heat up. I also attached a thermocouple temperature probe, just like I had done previously.

I worked my way around the board, heating the three chips gradually, and then concentrated first on the graphics processor, and then afterwards on the two memory chips. After letting it cool down, I then reassembled the laptop and was rewarded by a clean display with no signs of artifacts.

SONY DSC

Another successful “Reflow.IT“. I suspected that due to the nature of the problem where the memory errors occurred at different addresses and different bits that it was an intermittent connection problem with the chips. The reflow helps to melt the solder and let it solidify “hopefully” making good contact on all the chip connection points. It looks like it worked. Now what do I do with a laptop with a Pentium 4 and 512MB of ram. It runs Windows XP and has a 40GB disk drive and has a serial port on it, which is quite sadly lacking from most modern day laptops.

Advertisements

Reflow.IT – Dell XPS M1530 Laptop

This Dell XPS M1530 laptop came in a while ago.  I was busy at the time, so it got put on the back burner. Anyway, I was asked about it recently and of course, I hadn’t forgotten about it because I see it every few days, but I had left it – quite a long time.

The problem is that it doesn’t boot, or even get to a bios screen. It sits there with the fan and hard drive running, and just not boot. It will however, do a couple of things. If I press and hold the D button, then press the power button, it will come up and do a diagnostic on the lcd screen. Mainly going through a few different colors, white/grey, red, green, etc.

If I press the Fn button, then press Power, it will go into a diagnostic. It shows three possible lights using the blue keyboard status leds, NumLock, CapsLock & ScrollLock. The left one is flashing, and the middle and right ones are solidly lit.  From the internet, this indicates a CPU Processor fault. Solution is to – 1 Reset the CPU, 2 Replace the CPU, 3 Replace the system board.

Now this laptop had come in previously and I had replaced the system board. This was because one of the heatsink mounting tabs had come off the system board which meant that the heatsink was not making good contact with the graphics chip allowing it to overheat and therefore fail. Replacing the system board again, is no guarantee that the problem won’t happen again, so this time I decided to try a reflow.

Some background information – a number of nVidia graphics chips in laptops had problems whereby they would prematurely fail. It was known to occur in Compaq, HP, Dell and other brands so it wasn’t the brand, but actually the chip. It seems that these chips being a BGA (Ball grid array) had the wrong alloy of solder balls on it, so that when soldered onto the system boards, after some time, these solder balls somehow didn’t make contact. The only permanent solution to this was to remove the graphics chip and install an upgraded chip that did not use that alloy – of course, it is difficult to find out what alloy we need, and certainly, the manufacturers won’t tell us – but that is what we hear.

An alternative is to remove the chip, clean all the solder alloy off it, then reball it, by melting new solder balls to the grid array. I haven’t been successful in doing this because my cheap equipment isn’t up to the job or maybe I don’t have the experience. So plan B, is to perform a reflow. A reflow means to heat up the graphics chip to a high enough temperature, like 250 degrees, to allow the existing solder balls under the BGA chip to melt, and then allow it to cool, and hope (fingers crossed) that it cools down with all of the joints intact. Again, I haven’t successfully performed a reflow as yet, but maybe now I might get lucky.

I removed the bottom memory and cpu cover, removed the memory, then unscrewed the 7 screws that hold the heatsink on, remembering to remove the heatsink fan power cable. I removed a small piece of plastic from near the graphics chip. Then cleaned the thermal material from both the cpu and the graphics chip. The cpu was easy to clean, but the graphics chip has lots of chip capacitors on it, so we don’t want to scrub too hard, and it is often easier to leave the residue, but remove it from the contact surface.

I hooked up a temperature probe – a thermocouple to the graphics chip side, then it was time to “reflow.IT“. I have a smd rework station, which is a hot air machine, set to 300 degrees C, then by heating the graphics chip and surrounding area for a little while, then get closer to the graphics chip and go around and around it. Just basically aim the hot air onto the chip to get it evenly heated. The thermometer would go up when the hot air is in that area, then drop down. I did this for about five minutes gradually getting the chip hotter and hotter – the temperature only got to about 200 or so, but the chip itself was probably hotter than that. Anyway, after I thought it was ready, I stopped and let the chip cool down on its own.

I put some Arctic Silver 5 thermal paste onto the cpu and graphics chip – spread it around with a small piece of plastic (cut from an old credit or loyalty card). Mounted the heatsink, attached the fan cable, installed the memory and put the cover back on. Lastly, which I didn’t mention before, insert the battery. Oh, by the way, I had the laptop open with the keyboard facing down on the work bench when I was doing the heating up – you don’t want the heat to get to the lcd screen otherwise that will be damaged. A better way is to take the system board out of the laptop, but it was easier to leave it in.

Ok, acid test time – open up the laptop, press the power button…  My goodness, I see a bios screen, then shortly it starts booting up – success! My first successful reflow. I realize that I didn’t take a photo. By now, Windows had started and was asking for a password – ok, I messaged the owner for the password. In the meantime, could I try this with the old laptop which I still have lying around?

SONY DSC

This time, I took a photo to show the area around the graphics chip. The graphics chip is a nVidia chip, the one on the left. The cpu is the one on the right bottom. To the top left of the graphics chip, there is a hole, where a heatsink mounting nut should be. If this works, I might have to use some epoxy and put that nut back on.

I set the hot air rework station to 350 degrees. Then started heating the graphics chip – this time only for about 4 minutes or so. The temperature probe was showing that when the air was directed at the thermocouple, it was hitting 245 degrees, so this time, it should be hot enough – but of course, don’t have it too hot for too long. Ok, done – leave it to cool down, and check if a password had come through. Yes, it had – enter password and log on.

Success! This laptop comes up with a popup message each time you log in – it is a throwback from when it used to be on a Windows domain. I had a look and found that it was a script running from the Startup folder in the Program groups – deleted it, and this should fix this particular problem.

I left it to reboot, then reassembled the other laptop, put some memory in – didn’t have a hard drive to put in, but won’t need it. Plugged in a battery, then fingers crossed, pressed the power button, and… voila! I get a bios screen – that is two successful reflows today. Ok, now I need to dig out a few more laptops and try this out some more.

[Note] Previously, I had been trying to perform reflows with an infrared rework station, however I could never get the chips hot enough to be able to remove a BGA chip. Then a while ago, I had the need to work on some surface mount boards, to remove chips which needed a hot air rework station – that was when I got this rework station and the infrared station got relegated to the garage.

[Edit] Updated diagnostic light indicators.