ZD7000 Power Connector and Flashing LED Problem Solved

[newstemp]

I started having "brown out" problems a few months ago. Power LED flashing & screen flashing between min and max brightness. Twisted the power plug and eventually the flashing stopped. The situation deteriorated until the battery would loose charge (charge LED not on) and the computer would shut down. I thought that it might be the battery or power adaptor.

I opened the computer reaching the motherboard (not so difficult the second time around) and resoldered the DC socket to no avail. Openloop adaptor voltage was 19V (correct), however DC jack only showed 1V when the power was connected.

Then I noticed the two side spring pins inside the power plug (unusual for such a connector) that are designed to connect with the motherboard DC jack central pin. They had lost spring tension and no longer protruded into the central space of the plug. I used a large pin tool (large pin with handle, like a scribe, recommend a large needle otherwise) to wedge the side pins back out again, however only slightly. Problem solved.

However, the split metal cylinder inside the plug is at a different voltage to the pins (ground ? a sensing circuit ?), there is very little space between the side pins and this cylinder, and an accidental short circuit between one of the side pins and this cylinder with the adjusting tool, while power is on, will cause a flash and an arc, so make sure that the power is off for at least 30sec before making the repair.

Also, only adjust the side pins slightly and evenly without twist. If they protrude too far into the central space unevenly then can briefly make contact with the internal cylinder while the plug is being connected and you will hear an arc. The arc does not appear to have affected the power supply.

These should not have failed within three years and few connection/disconnection cycles. The side pins may need to be adjusted again within a year or so.

If the problem turns out to be the motherboard DC jack, these are easily available on Ebay, try "ZD7000 jack" or "ZD7000 connector". The DC power plug is also available here. I would not recommend a regular DC power plug replacement unless the function of the internal split cylinder is understood and found to be unnecessary.

Other advice for this overheating computer is do blast the air vents twice+/year to clear the heatsink dust (reverse vacuum cleaner or can or compressed air), and raise the back of the computer at least 1" (I am currently using a telephone directory just under the rear rubber feet) to greatly improve air flow. You will hear the fans run much more slowly and more quietly with these two measures. It also stopped my computer from regularly shutting down.

I am also going to go one step further and get a laptop support that will raise the screen about 6", placing it at eye level, and further improve air flow. Overheating may also be the source of some of the other problems mentioned for this computer.

DH