HP laptop with no power. Can you help me understand the DA0R75MB6C1 schematics?

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

You measure after PL20 and PL21 to ground, not directly from the chip to ground. Even though it wouldn't matter much if the inductor is ok because of its low DC resistance...

I get 0 ohms measuring PL20 and PL21 to ground. How would I go about finding what is shorted?

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

You said it had a shorted USB port. What exactly did youy remove? I would start with the USB driver chip. The easiest way to find shorts is with a thermal imager but that's not something many people have access to.

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

You said it had a shorted USB port. What exactly did youy remove? I would start with the USB driver chip. The easiest way to find shorts is with a thermal imager but that's not something many people have access to.

One of the auxiliary USB ports was crushed and shorted. I just disconnected that board. It wasn't one of the USB ports on the main board. Not sure if it is related or not.

Speaking of thermal, I can feel warmth from the area with the 3v and 5v chips. I will explore some more.

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

Can you identify that board you removed on the schematic?

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

Can you identify that board you removed on the schematic?

Page 29 "LAN conn & Right SIDE USBX1"

If I pull PL20 and PL21 from the board, would I be able to isolate the short to one side of the inductor or the other?

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

Page 29 "LAN conn & Right SIDE USBX1"

If I pull PL20 and PL21 from the board, would I be able to isolate the short to one side of the inductor or the other?

Yes you would but I doubt its on the regulator side.

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

USB_PO+ and - from that USB port go to the chip on page 6.

If the port was crushed there may have been a short from 5VS5 to ground and /or to the USB data lines.
If it was me I would probably remove the PL20 / PL21 inductors and apply a voltage directly to were the 5V are supposed to be, with current limit starting from 0A slowly increasing. If there is short in a component that component will heat up.

Trying to isolate the short by cutting traces would be too cumbersome.

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

Alternatively, if there is anything else you could remove from the mainboard I would do that first. Modules, ICs, everything, leave only the mainboard and DC power.

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

USB_PO+ and - from that USB port go to the chip on page 6.

If the port was crushed there may have been a short from 5VS5 to ground and /or to the USB data lines.
If it was me I would probably remove the PL20 / PL21 inductors and apply a voltage directly to were the 5V are supposed to be, with current limit starting from 0A slowly increasing. If there is short in a component that component will heat up.

Trying to isolate the short by cutting traces would be too cumbersome.

Time to invest in a bench power supply then.

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

Yes

I was able to confirm today that there is no EN voltage on either chip. It seems that the short circuit is causing "S5_ON" to not be present.

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

I was able to confirm today that there is no EN voltage on either chip. It seems that the short circuit is causing "S5_ON" to not be present.

EN comes from the chip on page 33 which needs +3V at VCC to work, I can't seem to find where this comes from...

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

EN comes from the chip on page 33 which needs +3V at VCC to work, I can't seem to find where this comes from...

That's pin 11 for VCC, right? I am getting 0v.

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

yes that's for VCC. try to find where that comes from. but you still have a short on the output of those chips...
not exactly the easiest board for a first time component level repair :-)

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

yes that's for VCC. try to find where that comes from. but you still have a short on the output of those chips...
not exactly the easiest board for a first time component level repair :-)

The meter I was using was complete shit, so I think I may have been mistaken about the shorts to ground on the outputs, at least on PL21. It is 2.5ohms to ground.

PL20 is currently open to ground because I removed and reattached the power IC and probably didn't get all legs connected.

So maybe it's not as tough of a case as it appeared to be. Bench top power supply is in the mail so hopefully I can crack this egg soon.

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

yes that's for VCC. try to find where that comes from. but you still have a short on the output of those chips...
not exactly the easiest board for a first time component level repair :-)

Injected 5v 1A into the system side of the 5V line and the ISL6277A chip got uncomfortably hot. It doesn't look like that chip is for sale anywhere tough. Is this the end of the road?

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

Maybe it's not that chip but something on the outputs? I would check all outputs for shorts to GND first.

See page 3 here:http://www.intersil.com/content/dam/...6/isl6277a.pdf
to identify them.

Test UGATE, PHASE, LGATE and PWM outputs.

The MOSFETs being driven are on the next page in your schematic (p39). Check them out too.

[paulstef]

Re: HP laptop with no power. Can you help me understand the shematics?

http://www.aliexpress.com/item/ISL62...rchweb201560_1

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

http://www.aliexpress.com/item/ISL62...rchweb201560_1

Thanks for the link. I have one on order just in case it is the chip.

Excuse my ignorance, but how can I go about checking the output for shorts? My only guess is to remove the chip and check resistance from the output pads to ground. Would that work?

[mattpd]

Re: HP laptop with no power. Can you help me understand the shematics?

Maybe it's not that chip but something on the outputs? I would check all outputs for shorts to GND first.

See page 3 here:http://www.intersil.com/content/dam/...6/isl6277a.pdf
to identify them.

Test UGATE, PHASE, LGATE and PWM outputs.

The MOSFETs being driven are on the next page in your schematic (p39). Check them out too.

ISL6277A removed

Pin 18 to ground = 2.5ohm
Pin 19 to ground = 2.5ohm
Pin 26 to ground = 15ohm
Pin 32 to ground = 0.5ohm
Pin 35 to ground = 1.5ohm
Pin 45 to ground = 11ohm

Removing FETs next to test them...

FETs removed:

On PQ3, PQ4, and PQ6 resistance between S and D is open, until touching the gate with red probe and then 0.5ohm between S and D (seems normal to me).

PQ7 the resistance between S and D is 160ohm until touching gate and then 0.5ohm.

So it seems like as though PQ7 is working (opening and closing) but it has a much lower resistance between S and D than PQ6 (which is the same part number). PQ7 must be bad, right?

[diif]

Re: HP laptop with no power. Can you help me understand the shematics?

Try testing the FETs using the diode function on your multimeter.