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Intermittent Black Screen & LED Flashes


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#1 trinibajan

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Posted 23 September 2011 - 03:17 PM

HP Pavilion Dv7 1129wm Laptop
Window 7 ROG 64-bit
Ram 4 GB
AMD Turion x2 M-72, Core VID 1.100V
ATI Radeon HD 3200 Graphics

When it boots the fan runs and all the lights on the board are on all at once but I have a Black Screen. Three seconds later the fan will go off, black screen status still but with a Cap lock and Num lock LED flashing together in a diagnostic code. One flash it appears.Which according to HP site means CPU is not functional, see: http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01443366&lc=en&dlc=en&cc=uk&lang=en&rule=26781&product=3816592

1. So I turned the laptop off, take out battery and press power for a hard reset. I then plug in the laptop without the battery and turn on. I get a the same results as above. Black screen.

2. I then take out both of the RAM sticks and put them back into the Ram slots. I start the laptop again and it gives me a seamless boot to Windows 7.

3. I check the event log and see minor errors in the past. Nothing to serious that would cause a black screen. I shutdown windows for a restart.

4. Window 7 fails to restart, Black Screen again with the same LED sequence flash from the Cap/Num Lock.

5. I power down, power back up with the same results.

6. I power down, take out one of the 2 GB Ram sticks. power up again. It boots up perfectly and recognizes the 2 GB Ram.

7. I shutdown for a restart in windows 7. Works fine on reboot.

8. I shutdown from Windows 7 and power back up. It dose not not boot. Same results as number 4.

9. I dismantle the Laptop, clean vent, heat-sink, CPU. Reapply Thermal paste and re-seat the CPU. Put back together.

10. On battery I try and boot up. Same results as number 4.

11. I repeat number 6 and it boots fine.

12. I repeat number 7. Works fine.

13. I repeat number 8 with its same result.

So I am here now to see if anyone can help me figure out what the problem could be and why I am getting such results. Any help would be highly appreciated. Thank you for your response in advance. :morn:

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#2 MrBruce1959

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Posted 27 September 2011 - 01:11 AM

Hello and welcome to Bleeping Computer.

Your pictures say a 1000 words, thanks for including those. :thumbup2:

I looked through your photos looking specially for leaking electrolyte from your surface mount electrolytic capacitors. Now from what I could see, there is no signs of this happening.
However, I suggest that you take a closer look for this yourself, they are those silver colored cylinders with the black colored base.

Now looking at your description above, it appears your problem is resolved when you remove your RAM from the slots and press them back in again.

So that tends to make me stick in this general area for the problem.

Here is a suggestion that might completely resolve this problem, purchase a tooth brush that you can keep handy as a cleaning tool for future use, make sure the bristles are short and stiff.
I do not recommend using one that has had toothpaste on it, this will only leave a residue and is not what we want to happen.

Remove the RAM from their ZIF slots, take the toothbrush and point the bristles into the slot so the bristles make contact with the copper contacts, run the bristles back and forth about 20 times.
Take the RAM and clean the copper contacts with the toothbrush running the bristles back and forth a few times. Avoid touching those contacts with your fingers, oils from your fingers can corrode copper.

Place the RAM back into the slots, if there are two sticks, try one at a time and switch between the two to see if one stick is faulty.

Once both are a go or no go or you determine both are okay, try shutting down and starting the laptop from a cold boot to see if the problem has be resolved.

Then come back here and post the results.

Bruce.
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My Career Involves 37 Years as an Electronics Repair Technician, to Which I am Currently Retired From.

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#3 trinibajan

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Posted 28 September 2011 - 11:27 AM

Thank you Bruce. I will try cleaning the copper connects and post if this has helped. Since I have meditated on it I believe it is the RAM. It may bot be getting a good connection. I believe I was not firm enough re-installing them. I will try what you suggested and get back to you. Thank you for your time and response once again.

Selwyn S. Baptiste

Edited by trinibajan, 28 September 2011 - 11:27 AM.


#4 trinibajan

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Posted 16 October 2011 - 06:52 PM

To test the RAM I removed it and installed into another laptop and it was recognized. So there is nothing wrong with the ram. It must be the Motherboard unfortunate. I have suggested to the client to just sell off the working parts and invest in a new Laptop. Dell Inspirion 1501 was made if 2005. It's time to retire it. Thanks for the help and suggestions though. I really appreciate it Bruce! :clapping:

#5 MrBruce1959

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Posted 17 October 2011 - 06:21 AM

You are most welcomed. :thumbup2:

Kind regards......


Bruce.
Welcome to Bleeping Computer! :welcome:
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My Career Involves 37 Years as an Electronics Repair Technician, to Which I am Currently Retired From.

I Am Currently Using Windows 10 Home Edition.

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