dag31amb6d0 no image

[marcelofct]

Hello, friends, i need your help,
I have a hp dag31amb6d0 rev d motherboard, when connected to the power source, it turns on, but njo gives me an image, install a bios from this website, check and the fan does not turn, nothing
In summary :
I have light on the power jack, 3v on the power button
I do not have 3v always nor 5v always, i turn on the laptop with the start button but i do not have amperage consumption for me it is very strange, this happened after they tried to change the hard drive for an ssd then it did not turn on anymore
I leave the schematic in case someone helps me solve this dilemma

[mon2]

Re: dag31amb6d0 no image

Hi. See attached.

Meter in DC volts (20V or higher is ok) scale.

Measure the voltage to ground of each of the requested 3 points.

Red probe to point to test; black probe to ground ((Brooke) shield(s) is ok).

Post each measurement.

[marcelofct]

Re: dag31amb6d0 no image

Hi. See attached.

Meter in DC volts (20V or higher is ok) scale.

Measure the voltage to ground of each of the requested 3 points.

Red probe to point to test; black probe to ground ((Brooke) shield(s) is ok).

Post each measurement.

1.- 19V
2.- 25V
3.- 6V

thank you !!

[mon2]

Re: dag31amb6d0 no image

These are good readings. Meter in resistance mode. Remove all power. Check the resistance to ground of each of the coils linked to the always on rails. Maybe a shorted cap on the rail.

If not low resistance, check the voltage to ground of the EN pins on the always on regulator. Post all readings.

[marcelofct]

Re: dag31amb6d0 no image

These are good readings. Meter in resistance mode. Remove all power. Check the resistance to ground of each of the coils linked to the always on rails. Maybe a shorted cap on the rail.

If not low resistance, check the voltage to ground of the EN pins on the always on regulator. Post all readings.

PL29: +5vs5_s : 8.3 kohm
PL30: +3V3s5_s : 12.7 kohm

It is the only thing I found.

since when connecting the charger I do not have voltages in the inductors mentioned only in the power button 3.3V


EN PINS
PU19: EN1=3.3V EN2=4.3V
PU18: EN= 3.3

[mon2]

Re: dag31amb6d0 no image

See attached,

1) the resistance readings do not show a short circuit

2) are the circled parts a solder blob on each point ? If yes, remove the solder blobs so we can focus on the regulator voltage for each only.

That is, the voltage at the inductor should produce the respective voltage without a load.

3) the enable pins are good and this means the upstream logic is requesting for these regulators to enable.

From past reviews, these regulators are wimpy and they do blow often. You may have to replace each if you see the VIN voltage to be ok.

Update - confirm the voltage to ground of each LDO pin on these regulators as well.

Confirm each measurement.

[marcelofct]

Re: dag31amb6d0 no image

See attached,

1) the resistance readings do not show a short circuit

2) are the circled parts a solder blob on each point ? If yes, remove the solder blobs so we can focus on the regulator voltage for each only.

That is, the voltage at the inductor should produce the respective voltage without a load.

3) the enable pins are good and this means the upstream logic is requesting for these regulators to enable.

From past reviews, these regulators are wimpy and they do blow often. You may have to replace each if you see the VIN voltage to be ok.

Update - confirm the voltage to ground of each LDO pin on these regulators as well.

Confirm each measurement.

2) are the circled parts a solder blob on each point ? If yes, remove the solder blobs so we can focus on the regulator voltage for each only.
nope , no problem with that


From past reviews, these regulators are wimpy and they do blow often. You may have to replace each if you see the VIN voltage to be ok.

i hope nop

Update - confirm the voltage to ground of each LDO pin on these regulators as well.


PU18: pin8=19V pin2=0V
PU19: pin8=19V pin2=0v

Now while I was taking the measurements, PU19 got hot. I will remove it to make measurements.

[mon2]

Re: dag31amb6d0 no image

if hot with no load = defective regulator. The parts are not expensive if bought from Aliexpress. You may even have a local shop that has them in stock if they do similar repairs.

You must, repeat must purchase the same part # as shown in the schematics.

SY8208B ; PU19 the suffix is important and defines how the EN pins function.

Here is a shop we have used a number of times without issues:

https://www.aliexpress.com/item/3264...d=CxSH5Ss8VOp9

SY8208C ; PU18 the suffix is important and defines how the EN pins function.

https://www.aliexpress.com/item/3263...500004035517_1

[marcelofct]

Re: dag31amb6d0 no image

if hot with no load = defective regulator. The parts are not expensive if bought from Aliexpress. You may even have a local shop that has them in stock if they do similar repairs.

You must, repeat must purchase the same part # as shown in the schematics.

SY8208B ; PU19 the suffix is important and defines how the EN pins function.

Here is a shop we have used a number of times without issues:

https://www.aliexpress.com/item/3264...d=CxSH5Ss8VOp9

SY8208C ; PU18 the suffix is important and defines how the EN pins function.

https://www.aliexpress.com/item/3263...500004035517_1

thank for links

I removed PU19 and the short to ground is still on pin 10 and 4. Do I apply voltage to identify the short or not?

[marcelofct]

Re: dag31amb6d0 no image

I applied voltage and the cpu heats up