Compaq Presario CQ71-411EG wont turn on

[123XYZ123]

Hello guys,

Im new here on forum but also in all this, a total newbie, so please have some mercy

The laptop Im trying to repair is:

Model: Compaq Presario CQ71-411EG
Product: VX896EA#ABD

CPU: Intel Core 2 Duo T6600 / 2.2 GHz
Graphics: NVIDIA GeForce G103M - 512 MB
Motherboard:

• DA00P6MB6D0
• PCB 0P6 MB
• REV D

The problem Im having is that the laptop wont turn on at all. When I connect the power adapter the LED of the power jack turns on for about 5 - 10 seconds and goes off, thats all I get, no other sign of life.

I did some research on the forum and found a pretty similar case with the same symptoms Presario CQ61 Dead- Not Booting - by nogger

I decided to make a new thread because its not about the same laptop (but same motherboard) and not the same BIOS, i guess.


Now back to my problem,
This is what I have checked so far:

1. Measured the voltage going into the motherboard and I got close to 19 volts so I assume the power jack is alright.
2. I checked the power button with my multi-meter for continuity and well I got the beeping so I would assume its not the power button either. Best would be to test it with a new power button, i know. However, I somehow doubt that the power button is the problem.
3. Now that I know its not the power button (most probably) nor the power jack I tested the voltage in other chips. I didnt know which exactly to test because I dont have the diagram but even with it I dont think I would be able to read it correctly. However, I tested almost all of them and in some I had 18+v volts, in some 5+ volts, some with 3+ volts. Those close to the power jack and battery seemed to be fine, so I guess the power is fine.
4. Knowing that its none of the above I removed the hardware from the motherboard one by one to see if maybe some of it is causing the problem. Firstly i removed the battery, then HDD, then the RAM Memory, DVD, USB board, audio board and the speakers,mouse board, wireless card, again it didnt power up, guess these arent causing the problem either.

After doing all the tests I came here and found the problem with BIOS which I assume is also mine problem.
I need your help to choose the BIOS and find it, I tried to find it but without success, couldnt find anything on HPs site.

First of all, I would like to know is if I can use the same BIOS as the one for Presario CQ61 because that one is available in the thread I shared and the laptops have the same motherboard.
Edit: I found the BIOS for my laptop. The file name is the same as the BIOS file for CQ61, so I guess I could use the BIOS from the other threat too.

Second thing is, where can I find the software for BIOS programming, or does the software come together with the programmer I purchase? For the serial number after the reprogramming I understood that I have to use the HP DMI tools which I already downloaded and have them ready. Not quite sure how to use it yet but I will google it.

And the last thing is, which programmer to buy. I cant spend much money so if some Chinese cheap ones can do the job I would be happy with it. Would this one be alright? High-Speed USB SPI Programmer EZP2010


Thanks a lot in advance guys!

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

Me again guys

I got myself a programmer and have read the chip with the software and it says its a:

Type: 25 spi flash
Manufacture: WINBOND
Memory Name: W25X80

When I tried to read whats written on the chip, with some effort I managed to see and it is written as the software reads it, so its definitely a chip from Winbond.
Now my concern is that usually this motherboard had a 25 spi flash - eon - en25f80 chip when I read it on other threads.
Now does that mean I have to find another BIOS rom or I can flash the one from the HP site no matter the version of the chip?

Thanks!

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

W25X80 is your bios chip. Read and save the old dump.
Download bios from web:
http://ftp.hp.com/pub/softpaq/sp51501-52000/sp51527.exe
Unpack with 7zip, write the .fd file to chip.
After that you might need to enter sn and other mainboard data with hp dmi tools.

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

Re-flashed the BIOS twice with the above file by khaahk and another one for same motherboard but no luck the laptop still doesnt want too power on
All I get is the LED on the power jack which turns on for about 4 seconds and then goes off
Was hoping that the BIOS was the problem but seems it obviously isnt.
Any other suggestions which I could try?

Thanks.

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

Is your power adapter working 100% ?
Is the battery being charged?
Does the w25x80 have 3.3v on pin8?
How much current is drawn from the adapter when connected, does it change when pwr button pressed?

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

Yes my adapter is working 18.82 volts, same voltage I measure in the power jack and in few chips around the power jack. On the battery I measure on some pins about 3V, on some 0.6V and some 0.
Im not quiet sure which one is the pin 8 on the w25x80 so I made a picture.

Would you mind if I take pictures of both sides of the motherboard and write down the voltage on every chip and its pins, because Im not quiet sure which ones are important and which voltage they should have? I found 2 without getting any voltage but maybe its normal.

Thanks again for your time and help

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[ktmmotocross]

Re: Compaq Presario CQ71-411EG wont turn on

http://forum.hwbot.org/attachment.ph...1&d=1328254478

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

Did the erase, write, verify go without error when programming?
How did you program the chip, offboard or onboard?
If you have the skill then measure current when adapter connected and see if it changes when power button pressed. How much is it?
If not - then see if anything is getting hot. KB3926 maybe.
quanta op6 schematic is available on the web, if you like to learn a bit.

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

Thanks ktmmotocross

khaahk Yes the programming went without problems. I took the chip of the board and then used my programmer to do the job. I didnt solder the chip to the programer I just hold the chip tight to it (the place marked on the picture) and it was able to read it and write the BIOS to it. I tried both BIOS versions the one for CQ61 and the one for CQ71, currently the original BIOS is on it, the CQ71 one. Also, I made a backup of the BIOS which was on it.

Unfortunately I dont really know how to measure the current. I will check if the KB3926 is getting hot or anything else.

Another thing, I dont have the original charger. I used the one from HP 620 and cut of its Charger Adaptor Plug Connector and soldered a new one for CQ71. The adapter is a 65W one and the original as I saw is 90W, does that matter too much? However, I remember that it had the same problem with the original charger too, so I doubt that the charger is the problem.

If you guys could share with me some free PDF books or some tutorials about motherboard repairs and electricity it would be awesome

Thanks again!

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[ktmmotocross]

Re: Compaq Presario CQ71-411EG wont turn on

do u have 3.3V on powerbutton dropping to 0V with button pressed?

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

I will check that, where exactly to search for the 3.3V on the powerbutton board?
About if anything is getting hot, I didnt feel anything hot, I let the board connected to power for about 10-15 minutes.
Also, I found about 3 chips (same size as the bios chip) which dont have any voltage on any of the pins and 2 other chips without voltage which dont have the same shape. Is that normal or should I take pictures of them and post them here, I got myself a magnifying glass so the pictures should be a bit better.

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

Yes after pressing the powerbutton the voltage goes down from 3.3V to 0V, only on the area which I marked.
Later when I have some more free time I will take pictures of the chips without any voltage.

[ktmmotocross]

Re: Compaq Presario CQ71-411EG wont turn on

now u need to check it on KBC IC.

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

The power button is connected to pin 19 on KB3926.

Still i would suggest to test it with known working adapter - mainboard has the adapter id pin and it most likely checks for the adapter type.
Or use a 200k (if i remember correctly) resistor from + to id pin to fake the smart adapter.

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

I couldnt find the KBC IC the only one starting with KB was KB3926, so I checked it. On pin 14 (marked on the image) the voltage goes from 3.3V to 0V when the power-button is pressed. When I put my red cable between pins 8 and 9 or 9 and 10, the LED 1 turns on (red light). On the opposite site when I put the red cable between pins 4 and 5 the LED 2 (white light) turns on. I tried to press the power-button while the red light was on but the fan didnt start to spin so guess the motherboard didnt power on.

khaahk, would an original CQ61 adapter be good enough? Its really hard to get the CQ71 adapter here but my friend has a CQ61 laptop and uses the original adapter.

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

I would not connect two pins together not knowing what signals they carry. CQ61 adapter should be fine, i think.
Check if pin 90 goes low for a moment when powerbutton pressed. That should give southbride a signal that kb3926 wants to power up the machine. If not then kbc either does not work or has an error condition (no adapter, lid closed - check pin 127 for 3v) etc.
Southbridge should then respond with bringing pin 6 and 16 to low state, i believe.

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

Pin 90 stays on 3.3V after power-button press, so it doesnt go low and pin 127 has 3.3V.
Does that mean that I have to replace the whole kb3926 chip? Whats probably impossible for me to do

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

Not exactly - it might also indicate an error condition that the KB3926 does not transfer the command to southbridge. Try the other adapter before anything else - just to rule that out.

[123XYZ123]

Re: Compaq Presario CQ71-411EG wont turn on

I found 2 capacitors (small ones) which have continuity on both sides and few of the main capacitors which also have continuity on both sides. Are they bad?

[khaahk]

Re: Compaq Presario CQ71-411EG wont turn on

Low ohms (~6-20 ohms) is ok if the caps are in cpu and video power circuits. Without cpu the low resistance should go away. Gpu is harder to remove...
Use shematic to find where the caps are in circuit.