Tuesday, October 26, 2010

Gateway MD2641U - USB and Shutdown Problems

Gateway USB ports not read -

This Gateway MD2614U would not recognize the USB ports or devices plugged into the unit. The problem was found to be manufacturer packaging mistake.  Unit made by ACER in Taiwan has a large plastic cover on bottom of motherboard, but the surface mount resistors coils, and capacitors were not wave soldered well, so the bonds were not sticking to mobo, instead to the adhesive on the plastic. About 12-15 SMT parts were stuck to the plastic and had to be manually placed on the motherboard in their correct location for the USB ports to be read.

The original reason this unit arrived was black screen/no video. Similar to the problem with the DV series using nVidia GPU though this was an ATI Chipset, the Southbridge and GPU were reflowed to assure solderballs were connecting under the chip itself.

How did I find out this issue?  Near the USB connectors the resistors were identified by their circuit designation, in this case it was the 300 series. (R353, C323, L341 etc) so checking under the plastic many of the parts were from this circuit. (see closeup as example)

The size of these parts are about 4 sugar crystals in a square pattern.

One part at a time was removed, folding the plastic toward board to see where it came from, then removed and one lead was soldered with needle point iron. After all the parts were placed on the motherboard, flux was added to the area and the other lead was soldered.  After both sides of parts were soldered, the whole area was reflowed with low setting on heat gun.  This was done to center parts on pads and to evenly flow the solder, and to help reflow any additional parts that may had only one pad connecting and  not visible to magnification. Also it is the recommended 
repair process to correct solder defects. (corrected solder
is shown in the lower picture)

Scotch tape was placed over the adhesive to keep additional parts from sticking again-notably the parts in the 200 & 300 series circuits. (The 200 series parts were used for the card reader to left)

To remove the parts from the adhesive, the tweezers were slightly heated to make it easier for the release from the sticky bottom. Be careful not to grip the parts too firm because they will fly from the tweezers and very difficult to find!

Good Luck!

Note: I've gotten another of the same model with different issues, this solution will be posted when opened.