Are reflow services all you perform and will a reflow fix a blinking jack on a… Compaq CQ50?

I get asked this question fairly often, and the answer is no. We do not simply repair systems like the Compaq CQ50 that are affected by the Nvidia chipset issue; as a side note, the issue is not just related to Nvidia chipsets since it also affects Intel GPU based systems along with ATI GPU based systems also.

As an example we received a local drop off service for a Compaq CQ50-139WM laptop system that displayed a flashing DC jack and no power to the system.

The DC power jack blinked in a uniform fashion to indicate an error code, but error codes are not detailed by HP or Compaq for blinking DC power jacks, to our knowledge for the Compaq CQ50 or any system. The Compaq CQ50 was delivered due to the belief it required a reflow service for the chipsets since the laptop is a common system to be affected here recently with a chipset failure, but upon further inspection this system is an Intel based laptop (506519-001) with an Intel based processor (SLB6M) and Intel based GPU chipsets (SLB8Q and SLB95) which are rarely affected by reflow issues.

Usually we test the memory to verify that the memory is not dropping the voltage since the DDR2 slots are reversed in the Compaq CQ50 line of laptops, but a blinking DC power jack does not indicate a short, no power, but indicates a reset from a power rail failure, a blinking DC power jack.

Currently, we have a system with an Intel motherboard from a Compaq CQ50 laptop, a blinking or pulsing DC power jack, and memory that is not found to be failed.

Our only option is disassembly of the laptop to verify the issue from the circuit level diagnostics using our Fluke based testing equipment. We use a simple Fluke 117 RMS digital multimeter to test most motherboards in our shop. The multimeter can give you the best diagnostics for the laptop from our tests.

One hour later, our Compaq CQ50 laptop is disassembled and is lying ready for the troubleshooting we perform. For our testing, we only use HP branded OEM power supplies. The difficulty with using a non-branded power supply from China or a Targus adapter from Walmart is that the power supplies are variable rate and variable wattage which could lead to issues with diagnostics. A variable rate power supply may not supply the correct or higher level of Amps while still supplying the correct wattage which could lead to a false positive while diagnosing your system on the bench.

Before we even test the laptop again with power we test the power rail which is located by the DC power jack. We test the mosFET labeled U1 with a signifier of 4407 on the chip which is a known mosFET to fail in both HP DV6000 and HP DV9000 Intel based and AMD based laptop systems regularly. The chip reads 0.000 which shows our test equipment is working properly to begin. The way we test this chip is across the VCC and the Ground legs to measure the reading.

Now we plug the DC power jack in to signify that the power supply is good and blinking. We achieve this test outright by plugging the adapter in.

Then we move to testing the laptop system with the power adapter plugged in to the DC power jack with our Fluke 117 multimeter. The multimeter gives different readings from the same position telling us the mosFET may be damaged internally. The mosFET is a P-channel mosFET. The gates within the chip are switching on and off giving us the variable up and down ratings.

To be absolutely sure, we have to do a thermoelectric test by using our infrared thermometer. By using our thermometer we can get a reading of the chip and if anything internally is failing within the chip. The chip specifics state the chip to be in tolerances requires a 25C rating or a 77F rating. With this we test our infrared thermometer to check the office and get a rating of 76F for our room temperature in our office.

Then the chip after being plugged in to get a reading from the multimeter showed a rating of 86.5F

After attaching the power adapter to the DC power jack and gathering a rating we had a reading well outside the range for failure specifying this chip is the issue with the laptop.

Below is a video of our test displaying our findings with narration and explanation for those wanting to test or get a better understanding of the steps we took to test the unit.

Compaq CQ50 DC jack issue