Packard Bell EasyNote TJ72 "black screen"

[Hurup]

Hello Bad Caps

Seeking possible help to resolve problems with a Packard Bell laptop

type:

EasyNote TJ72-RB-909NC MS2285
Date: KS 091203
SNID: 94972339722
Serial no: LXBFL02004949C52200

The problem is black screen and lack of CPU operation:

When starting the Laptop the following happens:

Battery indicator is illuminated.
CD drive is activated shortly.
CPU cooler starts at high speed and then goes to low speed where it will be running until the CPU gets hot and require more cooling.
HD runs
Keyboard is not enabled.
Screen is totally black.
No POST warning sound signals.

Tried the following:

Have tried with external monitor to no avail.
Tested HD and found it 100% ok.
Have tried with excessive discharge Laptop (removed the battery and turned on the button for 30 sec).
Had boot CD in the drive.

[lefos]

Re: Packard Bell EasyNote TJ72 "black screen"

Well have you tried with other cpu? If you don't install the cpu what is its behavior ?

[Hurup]

Re: Packard Bell EasyNote TJ72 "black screen"

Hello Lefos

I do not understand exactly what you mean about the CPU!

The error on the laptop came when it was switched off after use. When you next time about 24 hours later will turn it on is not possible and the above error occurs.

I've googled a bit, since I do not understand that there is no indication of POST error!

Could it be because the BIOS has been damaged?

I have found a Service Manual for EasyNote TJ75 (not TJ72) from Packard Bell. This describes the ability to flash a new BIOS into the computer with errors like mine has.

I have no experience of such operations and would therefore like to hear others' opinions and experience.

It seems that my computer errors is commonly known when you Google.

[lefos]

Re: Packard Bell EasyNote TJ72 "black screen"

Hello,

I mean what happens if you remove the cpu and power on the laptop? Is it possible to try another cpu?

[tomodachi]

Re: Packard Bell EasyNote TJ72 "black screen"

probably a BIOS issue, reflash the BIOS

[atsio]

Re: Packard Bell EasyNote TJ72 "black screen"

Can you find test points TP37, TP191, TP62 and TP119? If yes, what are the voltages on those test points after you press power button?

[Hurup]

Re: Packard Bell EasyNote TJ72 "black screen"

Thanks for the advice

Atsio :

I want to perform voltage measurements on the MB with the power on !
I have a MB diagram for the Laptop which I attach.

Tomodachi :

For flashing a new BIOS to RAM circuit I am a little unsure about what the risk is, and is it possible to repeat the operation when an error occurs or is it just a one shot ?
I have found instructions on Packard Bell service manual for TJ75 Series .
I will flash the BIOS as a last try, as I do not have experience with this operation. I seek advice and documentation for this type of service.

Lefos :

I do not have the option of installing a second CPU.
Would you boot the Laptop without CPU?
What can I determine if I perform this operation ?

Note :

I just got a new detail about the error process. It starts with the Laptop working fine when it is turned off. The next time it is turned on , there is only a black screen , CD drive clicks once , fan is running, first fast and then slow rate.
An attempt to start many times with the same result.
After 3-4 days manages to start up again and Laptop seems to be running ok.
After it was turned off , it was not possible to start it up again. It is now 4 weeks ago.
There is no POST audio signals.

[atsio]

Re: Packard Bell EasyNote TJ72 "black screen"

Yes, do the measurements with power on (after pressing power button). I am afraid you have a problem with GPU but we can check it to see if the problem is there.

[Th3_uN1Qu3]

Re: Packard Bell EasyNote TJ72 "black screen"

Measure CPU Vcore (on the caps under the CPU socket). If it always stays at 0.9v, then the CPU is not being initialized and you 100% have a BIOS issue there.

[atsio]

Re: Packard Bell EasyNote TJ72 "black screen"

Measure CPU Vcore (on the caps under the CPU socket). If it always stays at 0.9v, then the CPU is not being initialized and you 100% have a BIOS issue there.

The vcc_core voltage level depends on the processor used and the design - cpu voltage regulator used. In that design (from what I can see and understand) voltage depends on CPU used.
You have core voltage before reset signal from Northbridge to CPU. So before bios post you need to check reset and clock signal.

[Hurup]

Re: Packard Bell EasyNote TJ72 "black screen"

Thank you for your interest and suggestions.

I will try them all today or tomorrow and then returns with my test results.

Regards

Hurup

[Hurup]

Re: Packard Bell EasyNote TJ72 "black screen"

atsio

I have measured the voltages at the test points as you described with a Fluke multimeter.

Result is:

TP37 = 1.79 v
TP62 = 0.00
TP119 = 1.54 v
TP191 = 1.78 v
Ref ground2

I have no sense of what the correct voltage should be?


Th3_uN1Qu3

I do not know what capacitor you think I should measure on!

Will you help me to show the condenser on the diagram of the CPU?

NB:

I have separated the cooling fan which looked quite clean from the outside, but it is completely stopped by the dust on the cooling grills.

That must be the reason for all the problems!

I am looking for a service guide to EN TJ72 I only have a service guide to EN TJ75-76 77-78 but they are not quite the same!

[atsio]

Re: Packard Bell EasyNote TJ72 "black screen"

Please check again TP62. Check and TP172 and all pins of U6.