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

Willen

Well-Known Member

• Nov 26, 2013

• #1

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

User Extraordinaire

Forum Supporter

Most Helpful Member

• Nov 26, 2013

• #2

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

 

ikelectro

Member

• Nov 26, 2013

• #3

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

 

Willen

Well-Known Member

• Nov 26, 2013

• #4

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 )

 

Last edited: Nov 26, 2013

ikelectro

Member

• Nov 26, 2013

• #5

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

Well-Known Member

• Nov 27, 2013

• #6

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

Member

• Nov 27, 2013

• #7

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

Member

• Nov 27, 2013

• #8

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

 

ikelectro

Member

• Nov 27, 2013

• #9

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

 

Willen

Well-Known Member

• Nov 27, 2013

• #10

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.

 

Last edited: Nov 27, 2013

ikelectro

Member

• Nov 28, 2013

• #11

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

Well-Known Member

• Nov 29, 2013

• #12

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

Well-Known Member

• Nov 29, 2013

• #13

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.