HP zso50 LA A994P rev 2.0

[Jmine]

This motherboard had a shorted cap, after repacing it the board turned on but with no display.
I checked a few voltages in the power on sequence, among others the PLTRST# is present.
Upon checking the LVDS connector I found that +LCDVDD is absent.
I am totally stuck here. Guys, I need Your assistance.

Could find the schematic for rev 2.0. But I have attached the rev 1.0 schematic and it is a bit different.

3VS to LCDVDD converter UG1 is absent on rev 2.0 board

[mon2]

Re: HP zso50 LA A994P rev 2.0

Review the wimpy load switch at UG1.

Measure the voltage to ground of each pin.

Then remove all power. Meter in resistance mode. Confirm there is no low resistance to ground on the LCDVDD rail that is causing an excessive current draw.

[Jmine]

Re: HP zso50 LA A994P rev 2.0

Review the wimpy load switch at UG1.

Measure the voltage to ground of each pin.

Then remove all power. Meter in resistance mode. Confirm there is no low resistance to ground on the LCDVDD rail that is causing an excessive current draw.

There's nothing at UG1 on the motherboard. What should I be looking for?

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

There's nothing at UG1 on the motherboard. What should I be looking for?

RTD2132S is there and its Pin 15 is +DP_ENVDD which then becomes +LCDVDD. The models where RTD2132S is there wont have UG1. So probe RTD2132S or if you have spare one ,just replace it.

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

Btw, is the mb posting? Numlock glows on usb keyboard?? If answer is no, then problem may be something else. So update us about the questions.

[Jmine]

Re: HP zso50 LA A994P rev 2.0

Btw, is the mb posting? Numlock glows on usb keyboard?? If answer is no, then problem may be something else. So update us about the questions.

There is an led on caps lock and it isn't turning on. There is an amber led on f12 key turned on though.Seems like the motherboard isn't posting.

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

Better, connect a usb keyboard and check numlock glows or not. If not, then mb is not posting at all-so needless to probe edp pins.

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

Consumption on dc supply
01.With ram stick
02.Without ram stick

Is it same??

[Jmine]

Re: HP zso50 LA A994P rev 2.0

Consumption on dc supply
01.With ram stick
02.Without ram stick

Is it same??

Num lock of USB keyboard doesn't turn on

@19V with Ram on 0.17A
@19v without Ram on: keeps on changing between 0.16 and 0.17A

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

So consumption is more or less same with or without ram?? meausre voltage on UF1 mosfet on Pin1/4/8. Most likely you will not get 1.0V on pin8 and may be less voltage is present. Confirm your finding. UF1 is located near SOC.

[Jmine]

Re: HP zso50 LA A994P rev 2.0

So consumption is more or less same with or without ram?? meausre voltage on UF1 mosfet on Pin1/4/8. Most likely you will not get 1.0V on pin8 and may be less voltage is present. Confirm your finding. UF1 is located near SOC.

Yes, consumptions are almost the same

UF1

Pin 1: 1.018V
Pin4: 5.217V
Pin8: 1.020V

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

UF1 is working fine. DRAMRST# present on pin30 of ram slot?

[Jmine]

Re: HP zso50 LA A994P rev 2.0

UF1 is working fine. DRAMRST# present on pin30 of ram slot?

Nothing on 30th pin.

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

Replace the ram stick. make sure its DDR3-L. Look for corrossion on ram slot. Flash bios.

If all these steps fails, then you need to probe PUM1 ic.

[Jmine]

Re: HP zso50 LA A994P rev 2.0

Replace the ram stick. make sure its DDR3-L. Look for corrossion on ram slot. Flash bios.

If all these steps fails, then you need to probe PUM1 ic.

I changed the ram stick now DRAMRST is present.( 1.3v)
Guess I have to flash the bios now.

[mcplslg123]

Re: HP zso50 LA A994P rev 2.0

Good. Now repeat the measurements at post#8. yes, flash known good bios.

[crownmobile3]

HP zso50 LA A994P rev 2.0
Masters plz help me to find out the Keyboard connector Pins to Flash EC. Thanks