Compaq Presario CQ57 - Does not work

[olorin]

Ηι...I have a problem with Compaq Presario CQ57.Seems to not get any power.The light is just beside to the DC-jack, does not light at all, nor any light on laptop.I tried another charger but I saw no difference.I opened the laptop to see if there are currents in the motherboard.I observed that the dc jack works normally since sending the normal 19.8 voltage in the motherboard.I did a little checking around on the dc connector parts, sitting the plug from the jack, and found that power does not go through the board but stops at the connector of the battery who measure in two of the legs 3.2 Volt.

The particulars given on the motherboard is:

657324-001
P/N: 01015PM00-600-G
CHICAGO_BR_HPC
MV_MB_V2
E253117
RC6F32071JH1
PCHMDA57V2K39U 02020C800-600-G REV 0N

I want the schematic diagramm to check out the components and your opinion on what to look ....
Thank you!

[cyberhack]

Re: Compaq Presario CQ57 - Does not work

Here
page 37

[LittleM@n]

Re: Compaq Presario CQ57 - Does not work

Same problem here; olorin, have you solved yours?

Thank you for the schematic cyberhack!

[polytek]

Re: Compaq Presario CQ57 - Does not work

check the power button if there is 3.3V

[LittleM@n]

Re: Compaq Presario CQ57 - Does not work

OK, the power button was lighting up, for about 10seconds, than stopped, without any other thing to boot. I've managed to trace the power from the input connector to the TPS51123, the power IC which generates 3.3V and 5V. The 5V rail was dead on the VO1, and the 3.3V rail generated 0.32V on the VO2.
The EN0 pin had 3.3V, the ENC pin had also 3.3V, the VREF was correctly at 1.99V, and VBST1 and VBST2 was 4.57V, VREG3 was 3.25V and VREG5 was 4.93V, so everything seemed fine, just that the VO1 and VO2 were not providing power.

Than, I realised that maybe this was ok, because the computer was not started, but still it didn't explained why there was no light on the LED attached to the power jack (that confirms the power brick is connected). I identified the 2 LEDs form the power jack and powered them independently with 3V, and the light up just fine (white and orange).

From the IC datasheet, the TRIP1, TRIP2, DRVH1, DRVH2, DRVL1, DRVL2, LL1 and LL2, all of them were 0V all the time. Vin was 18.5V. Although, the input from the power pin on the board was 19.5V (so 1V was somewhere dropped on the road to TPS51123). The IC was very hot to the touch only after 1 or 2 minutes since plugging in.

What I realised was that touching the pin 21 and 22 together (so VBST1 with DRVH1), made the LED on the power connector light up. Unfortunately, I had the same problem, my checking tip was too thick, and my hand slipped, so I've touched the Vin and VREG5 together and I believe that I "finally" burned the IC (now the values that I read are very low, 1.7V for both VREG3 and VREG5), so that's it.

I'm still not sure if the IC was the problem in the beginning, maybe I haven't identified the issue correctly, and there was another IC that generated the problem to the TPS51123.
Now, I'm debating if it's worth to attempt to replace the IC, as I don't have the appropriate tools and know-how to replace a 24-QFN IC, or to sell the laptop as parts. A sh fully working laptop like this is selling in this moment for ~100$, so if I'll attempt a repair I'll do it for fun, next time when I'll have some spare time

[sparker1]

Re: Compaq Presario CQ57 - Does not work

I don't have a thick DMM probe set either, so when checking these IC's I tape a pin to the positive probe.

[sparker1]

Re: Compaq Presario CQ57 - Does not work

Sorry, that should be thin instead of thick.

[polytek]

Re: Compaq Presario CQ57 - Does not work

replace the tps51123 and C1017