Thursday, July 8, 2010
Laptop Rebooting- DV6000, F700
While working on a DV6000 today I decided I should also address other problems with these models while working on the DVD production.
As it seems this problem is also quite common, Rebooting, looping, restarting. Never getting to the Windows startup screen.
OK there are several causes of this scenario with the ribbon cable being shorted or defective. The ends of the ribbon cable can lift away from the surface when inserted and shorting the lead from the adjacent wire. Some times it will short and cause the wire to burn. Other times it will cause the REBOOT/LOOP issue.
Also verify that the Coin Sized CMOS battery has 2.5v- 3v, if not or voltage is low, all kinds of problems may present themselves. Correct operating voltage is needed to read the CMOS data, or the data may be corrupt or deleted.
How to test/bypass these?
1: Disconnect the PWR connector cable, and turn the system on with the remote control (if you have one). Make sure the battery is good in the remote.*
2: Substitute with another cable.
Other issues presenting same problem
CMOS is bad** - If the CMOS is bad it cannot be read or written to- and the system continues to try to write/read data from it.
The Dual Channel MOSFET - one output is shorted or open. (or both)
When the MOSFET has about 3.25v on pins 1 & 3 it should be considered working. There should also be the same voltage on the Drain side (pins 5-8). This will take the voltage up to the legs on the PWR button and when the button is pressed this voltage drops to ZERO and the unit turns on. The original part was a AO4812 and sometime has been replaced with a ME4920.
*How can I test the IR remote?
Since most people have a digital camera nowadays the cheapest and easiest way is to press the power button on the remote and look at the camera's LCD display. You should see the remote blinking.
**How can I test the CMOS to see if it is working correctly
Disconnect AC adapter!
With the ribbon cable connected to the power button, hold the button for 15 seconds to clear the CMOS. Now hold the PWR button down, and at the same time insert the adapter into the DC JACK. The lights should come on for about 5 sec. then go off. Release the PWR Button. Now attempt to power on normally. Sometimes this works when the CMOS settings are bad.
Watch the orientation of PIN 1.
On DV6000 the leads are up
On the DV9000 the leads are down
On the F700 the leads are down.
If your memory/recall is bad- take a picture before starting.
Note: The black KOTEL ribbon cables are flimsy and the strain-relief/support is too close to the leads to help matters. Remove and insert less often as possible. If they break you'll wind up looking all over for a substitute. Though similar pitch and length cable can be found on GATEWAY MA3/7 touchpad. (Techs at shops should have a few of them around)
Also the Gateway MA3 has two of the AO4812 chips on the back side near the 28 pin power output IC. Incase you were needing one.