HP Pavilion g6 i5 Black screen problem

[itsmeacalling]

My Black Screen Problem started after I removed the CPU fan for cleaning. After cleaning I replaced the old Thermal Compound with Arctic 5 Thermal Compound, removing the old Compound using Arctic 1 and 2 cleaning fluid. After re-assembly and starting the machine I noticed screen flicker, the OS would load, Wi-Fi card working and Internet connection. But after a few reboots the screen just when black

Actions taken all without success..

1. Once again stripped down the laptop, removed the fan unit, cleaned up heat-sink and applied Thermal Compound. Reassembled the laptop

2. Hard reboot, I.e shut down laptop > removed battery and power supply, press start button for 20 seconds, powered up using power adapter

3. Connect HDMI cable to laptop and TV, but both screens black

4. Confirmed that the HDMI cable to TV is working by connecting an Android Tablet

5. Removed Hard Disk

6. Removed RAM (here I get 3 blinking led code indicating RAM problem, put back RAM and led blinking stops)

7. Checked and rechecked that all ribbon cables etc are connected

8. Looked on the internet and tried what ever I could find on the subject.

So it looks Like I have done damage but cannot see where, could it be the mother board or the screen?

Any help would be gratefully appreciated. Thank you.

[ieee488]

try connecting external monitor 

[itsmeacalling]

Hi. Thank you for your reply

Yes I have tried doing just that .HDMI to TV. Result both Laptop and TV screens Black. I confirmed that the HDMI cable was working as I plugged in my Android tablet and it worked.

When I start the laptop the following occurs...

Power led comes on

F12 key (Wi-Fi) LED starts orange then changes to white

Caps lock key LED works normally ( no blinking error codes displayed)

Hard disk LED working

The Fan is working normally

But still Black Screen

Got me completely stumped

[ieee488]

F12 key LED white means that Wifi is turned on.

Is there a function key combination to "cast" screen to external monitor ?

[itsmeacalling]

Yes, the F4 key in combination with the Fn key, I have also tried the F4 key by itself but still black TV and laptop screens. I will try once more tomorrow and report back

[itsmeacalling]

Hi, I have been doing some more investigation into my problem, below are my findings..

I connected the laptop to a TV using an HDMI cable, booted the machine and without pressing any keys the TV displayed Windows, the laptop screen remained Black. It takes a while to load though not normal for an SSD drive.

I replaced the SSD drive for a standard hard disk but the loading time is about the same as the SSD.

When I start the machine the fan runs what I would call a normal slow speed, after a minute or so the fan increases to a much higher speed and remains at the speed until the machine is turned off, note the air coming out is not hot.

If I boot the machine without any hard disk or SSD in the machine the behaviour of the fan is the same as with a hard disk or SSD in in place. I was expecting the fan not to increase in speed as no OS could possibly load. I was also expecting to see a message on the TV saying ‘no bootable devise detected’ or some sort of error message.

I tried booting to the BIOS by pressing the F10 but nothing is displayed on the TV so cannot check setting.

So it looks like the HDMI connection only works when the OS starts to load, any on screen (BIOS) messages you perhaps would normally see before the OS starts to load are not displayed. Perhaps there is no HDMI driver at this stage.

Regarding the fan, air coming out is always cool, it seem to be like a two step speed thing, slow for the first minute or so, there after the higher speed, fan speed never fluctuates.

Not sure what to do next. I have applied Thermal compound twice. Checked all ribbon/cable connections. Checked mother board for damage (burnt components etc). Cannot view the BIOS setting. So it looks like it could be the grave yard for this machine. Do you think there is any hope left

[ieee488]

When the laptop is booting up, ESC then F2 to get to BIOS.

The laptop screen is still blank.

Then do the Fn+F4 to switch to external monitor.

See if that works.

[itsmeacalling]

Hi

Pressing the ESC then F2 did not get me into the BIOS as the machine booted into Windows. I believe for my machine to enter the BIOS its the F10 key. So I tried ESC then F10. I believe I was then in the BIOS because Windows did not load. Pressing Fn and F4 shows nothing on the TV. I am beginning to think BIOS does not support HDMI but Windows does.

[ieee488]

ESC then F2 works on my older DM1 and 625 HP laptops, but yours might be different.

.

[itsmeacalling]

Hello,

I ordered yesterday a replacement screen cable to see if this cures the Black Screen problem.

Regarding the persistent high fan speed. I have looked on the Internet and it appears to be a problem with some HP laptops. The common solution offered online is to clean the fan, people who tried this said it made no significance improvement. I do not know the history of this machine so I do not know if the fan ran this way from being new machine. The fan fitted has three wires, red- black and yellow, so I presume there is a tachometer. Perhaps its a faulty fan unit or whatever reads signals from the tachometer.

Once I have fitted the replacement Screen Cable I will let you know the result.