HP DV5 power on for 1 second then back off

[Th3_uN1Qu3]

Have this DV5 which is exactly like the one i have, it's the AMD with dedicated HD3450 gfx.

It powers on briefly then back off. I found shorts on PQ41 (1.2v) and PQ55 (VGA core), but as expected, the MOSFETs are fine, the "short" remains on the board, and i believe it could be normal, as plenty of chipsets read a few ohms, sometimes even less. Don't have another board on hand to check, and i'm too lazy to take mine apart...

Also i think the GPU is alive as the screen flickers briefly before it shuts down. It came with a label saying "Faulty northbridge", but i don't believe it. No interventions on the board, red epoxy is present on GPU, NB and SB. Any ideas of what i should check?

The other one i fixed yesterday had been reballed both NB and SB before we got it (that was the IGP model tho), and it still didn't work. Can you guess the problem? Fried CPU... It even blinked the faulty CPU code (1 blink, long pause), but nobody figured it out.

Edit: VGPU and 1.2v for the NB do not come up. Vcore does. There really is something shorted on here, the question is, what's it.

[ben7]

Re: HP DV5 power on for 1 second then back off

Edit: VGPU and 1.2v for the NB do not come up. Vcore does. There really is something shorted on here, the question is, what's it.

Maybe it is a faulty NB

Might be a shorted MLCC capacitor.

Are Vgpu and Vnb the same voltage? (1.2v)

[Francisco.s]

Re: HP DV5 power on for 1 second then back off

Can you read de code number of the motherboard?. Help us to help you.
Anyway, check the signal HWPG, it goes to many circuits, and if it has a wrong level, the embedded controller, won't give the appropriate order.
Regards.

[Th3_uN1Qu3]

Re: HP DV5 power on for 1 second then back off

No, VGPU (labeled as VGA_CORE on the schematic) and the 1.2v rail powering (some of) the NB are two different voltages. It would be odd to be both shorted, but that's what it is. I'm sure the EC gives the power command, as the thing shuts down because the power supplies go into protection mode. It will start back up again if i hit the power button, and does the same thing again.

Unfortunately i don't have a high current bench supply or else i would have tried powering the thing externally and at least get a smoke indication of the failed part. It needs 12A at 1.2v and i don't even have spare AA holders, else i would have rigged up a bunch of NiMhs in parallel. I've given up on it, it's more trouble than it's worth.

Next up is a partially failed DV6000. It just needs a GPU reflow (my old friend the 8400M GS) and some tab bond fixes on the display. The LCD has a few horizontal lines which go away if i twist it, and the GPU is still alive but it only works for an hour or two with the driver installed, then it artifacts and crashes altho temps are quite cool.

[Francisco.s]

Re: HP DV5 power on for 1 second then back off

Hi @Th3_uN1Qu3, have a look to this schematic. I can see in it some of the components you mention, but not sure if it is the right one.

[Th3_uN1Qu3]

Re: HP DV5 power on for 1 second then back off

Yes, that is the schematic. I've given up on it anyway. DV6000 fixed btw.

I have yet another DV5 in, which has been reballed (poorly at that, the GPU is warped at the edges), and on this one there is no short on the rails i mentioned, although it has the same behavior, power on 1 sec and then off. Sometimes it will start up but graphics are badly corrupted once it gets to Windows. The other one did not start up at all, no matter how many times i tried.

On this one VGA_CORE has fairly low resistance (10 ohms or so), but it's by no means a short. The 1.2v rail going into the NB is clear, no beep from my multimeter. Either way, looks like we have two dead boards. Even if i did have the equipment to swap the chips, they're ~30$ a pop which makes them not worth it.

[Claudio Silva]

Re: HP DV5 power on for 1 second then back off

Friend all seems to be the NorthBridge, measure de inputs and the outputs, check if there´s any voltage

[Th3_uN1Qu3]

Re: HP DV5 power on for 1 second then back off

No voltage going into either NB or GPU on the one reading shorted, didn't bother to measure the other one.

I think i'm going to order some stencils and balls and try swapping the RS780M chip from the board with the (apparently) shorted northbridge to the one with the warped GPU. I said i'll never get into reballing, but hey, there's a start for everything. I do have both a hot air station and a bottom heater, so there's a chance of success. The boards are useless in their current state anyway.

[senchire]

Re: HP DV5 power on for 1 second then back off

I know its an old thread but did you saw what the problem is I have the same problem now ?

[Th3_uN1Qu3]

Re: HP DV5 power on for 1 second then back off

I've done a few of them since. With this behavior it's going to be the Northbridge usually. First measure on the capacitors on top of the chip to see if it is not shorted. If it reads ok, reballing should fix it.

[highpulse]

Re: HP DV5 power on for 1 second then back off

dv5 amd ? well pratically all fault i got is usually the bloody NB IGP or even somethimes the power for the IGP , a bad mosfet usually found on this board . i onl yhave caught one with dead cpu in my entire life eheheh , usuall ythe problem remain on this crappy IGP chipset and the poor system cooler .. making a AMD cpu near a very week chipset was really well thinked for HP to make machines to damage quicker (consume law at its best)

[Th3_uN1Qu3]

Re: HP DV5 power on for 1 second then back off

I have seen one or two with shorted CPU.

[highpulse]

Re: HP DV5 power on for 1 second then back off

ive got one now turn and off very quickly not even time to kill a cokroach ;\

, alltough cheked main coils nothign seems shorted , lifted IGP after chking caps , they seem fine , let see if the reball does something .

[highpulse]

Re: HP DV5 power on for 1 second then back off

np the same issue