Laptop starts to run automatically when charger pluged!! But cannot boot OS!

[Willen]

It's Compaq Presario CQ45. Battery was good but now it does nothing! Shows white LED (not charging). When I pluged a charger pin, HardDisk and DVD Drive runs automatically (without pressing Power button). But laptop cannot starts OS, even it cannot load BIOS. Fan is not running too. Is it a problem on Power Section on motherboard?

 

[Ian Rogers]

Could be a faulty ram stick... The fan doesn't run until temp has been reached..

 

[ikelectro]

if the laptop turns on automatically check the CPU Core power supply and other voltage regulator. make sure your VRM is Ok.....

 

[Willen]

Oh yes! May be VRM (voltage reg module) has been shorted so it tuns on automatically but loads nothing (BIOS/OS). Just screen is blank. I can hear a small smooth sound from HardDisk and DVD drive.

How can I locate the VRM, and how can I test its condition? Is there any simpler way? ( here are no chip level mechanics around my area )

 

[ikelectro]

First of all: can you disassemble your CQ45?????

edit: make sure that you have done the all card level troubleshooting before disassemble the CQ45.... like changing the RAM, removing the HDD, ODD (then try to turn it on).... removing the battery....

 

[Willen]

I already deassembled (RAM, HDD, DVD drive, Key-B, Housing, Fan, Processore) all parts. Main problem is 'it automatically starts to run when I plug an adaptor, battery doing nothing' so I think it's no worth to focus on RAM, HDD etc. I am almost sure it has faults on Power section I think. I cannot repair, replace ICs so anyhow I have to find Chip Level Mechanics on my area or out of my area.

 

[rmn_tech]

Sounds like a common Compaq fault. due to the video processor sharing a heatsink with the cpu.

The vpu chip needs reflowing at the very least. this is due to heating from the shared heatsink causing the solder on the vpu to become dry or actually melt enough to break connections.

I have successfully repared many Compaq's by doing this reflow however depending on the severity of the problem reballing is sometimes the only permanent cure. (NEV. (not economically viable))

 

[ikelectro]

your CQ45 with Nvidia (NB9M-GE)???

 

[ikelectro]

here is a block diagram for CQ45 found in net. may be you can get some help here....

 

[Willen]

Eventually I found a chip mechanics. He says that- main IC of power section might be shorted. He is going to replace to it.

Another huge problem is came- due to few days of power short the battery has been fullly discharged than safe zone. While booting laptop it shows some warining like- "battery is very than........replace another...."

Before shorting power section it was good. During shorting its all power was consumed!

Then please help me now- How can I recover the battery. Wil simple long charging help me?

Will create new thread too.

 

[ikelectro]

I don't think exactly it's main power ic shorted, main power ic of laptop(in this cq45) is BAT CHEM-- MAX8731 and SMPS IC --TPS51125...

 

[Willen]

I don't know exactly but mechanics was showing me a little bigger IC. He said he will replace it with new one and fix the laptop.

 

[Willen]

I don't know exactly but mechanics was showing me a little bigger IC. He said he will replace it with new one and fix the laptop.