Lenovo IdeaPad 320-15ABR DG526 DG527 DG726 NMB341 Rev:1.0 No screen

hi to all
Lenovo IdeaPad 320-15ABR
motherboard part no : DG526 DG527 DG726 NMB341 Rev:1.0
PQ1901 damaged (The pad is damaged)and after replacing 1.2 is ok. seems that all main coil voltage is ok.
PQ1901 pin 1-3 to pin 4 resistance is low.
in JDDR no voltage 1.2 in pin 124-118-112-129-123.......please advise me more test point
tnx

Hello!

Measure the resistances between listed pins of chip PU1901:
- Between pin 27 and pin 35.
- Between pin 32 and pin 33.
- Between pin 33 and pin 34.
- Measure the resistance to ground on pin 35.

- Measure the resistance to ground on coil PL1903.

hello

pin27 to 35=about 138k
pin32 to 33= 380k
pin33 to 34= 40 ohm
35 to gnd= 8 meg
pl1903 to gnd =about 3.5 meg

Amir написав:pin33 to 34= 40 ohm

This resistance seems too low.

Measure the voltage to ground on pin 31 of chip PU1901.

Amir написав:pl1903 to gnd =about 3.5 meg

Is this measurement correct?
Did you measure with the jumper PJ1911 closed?

sorry about 13 k
pj1911 is normally open
"Measure the voltage to ground on pin 31 of chip PU1901."
in standby or power on?

update:pin 31= 3.5v in power off
pl1903 voltage is 0.925v power off

Amir написав:sorry about 13 k
pj1911 is normally open

Please, measure this resistance again this time with the jumper closed.

Amir написав:in standby or power on?

When the machine is turned on.

Amir написав:update:pin 31= 3.5v in power off

This voltage should be 0V, when the machine is turned off.

hi
sorry for mistake
pin31 in on =3.5 v off=0v
other side of pj1911 is GND
pl1903 in standby =1v
without ram =0.5v
with ram= 0.2 v

Amir написав:other side of pj1911 is GND

And it shouldn't be.
Perform a short circuit test.
The APU processor and the OnBoard RAM memory chips are very likely damaged.

Amir написав:pl1903 in standby =1v

In St-by it should be 0V.

tnx matic
here is motherboard part number. The device does not have a label just idea pad320.if other side of jp1911 is not GNd Why is the jumper not closed?

I think we don't understand each other...

Please, measure the resistance to ground on the system side of the jumper PJ1911 (the side marked with an arrow).

GND i said before.
The jumper is normally open from the beginning

Amir написав:GND i said before.

It shouldn't be. Perform a short circuit test as suggested.

Amir написав:The jumper is normally open from the beginning

It shouldn't be. Maybe someone previously repaired this board and left this jumper open. It should be normally closed for sure.

I think I was the first person to open the device. I think the jumper was opened due to high current. With the short circuit test, UD3 and UD4 seem to be hot.

Is there a way to disable onboard ram?

Amir написав:I think I was the first person to open the device. I think the jumper was opened due to high current.

Considering the white silkscreen printing around this jumper seems worn, I don't think that's the case.

Amir написав:With the short circuit test, UD3 and UD4 seem to be hot.

Remove both chips from the board and remeasure the resistance to ground on the system side of jumper PJ1911.

Unfortunately, there is a very high possibility that all the RAM chips are damaged and the RAM memory controller inside the APU processor as well.

Amir написав:Is there a way to disable onboard ram?

I'm not sure, but I think there is no such a way as there is no description of "RAM strap" resistors in the schematic.

you are right matic .the device opened before
can edit bios for disable ram?

Amir написав:can edit bios for disable ram?

No, as far as I know there is no such an option.

By the way, in case of a short circuit to ground on the RAM power supply rail it must be resolved in any case - it's impossible to disable the OnBoard RAM in case of a short circuit.