Alienware x15 R2 no memory detected (hell repair job, 6 months later)

[jagiro84]

Hi guys,
its been around 5-6months since i left this board on side to rest my brain cells and now came back to try and repair it again.

The laptop in question has issue where it gives error code on power on which is 2red and 3 blue

In short, by Dell specs this means "Memory not detected: "

Now one important thing the laptop would turn on fine when i leave it in the refrigerator for 5-10min and i could work\play games with it for days and months as long as i dont turn it off
but after a while this trick stopped working as wel

so i finally had decided to replace the onboard Ram which is BGA DDR5, this job went smooth even tough it was my first time but still it didnt solve the issue, its still giving me same error code.


Here is a picture of some of the Voltage readings, i have also included the values that i could find inside the BoardView specs for comparison

the only thing that i can see on the BC0A IC is that on pin6 its giving 10v and on boardview it should be 1.8v_mem_CT
and pin3 gives 3.3v while on boardview specs it shows 1.8v_mem_en


i truly hope someone can see if i am missing something here or at least had similar job that can point me to the right direction

specs i7 12gen
GTX 3070ti

[mcplslg123]

Pin7 and 8 of PUM1 should be 3.3V in my opinion as these 2 pins are the enables for ram IC.
You have not listed voltage on pin7 and pin8 voltage shown is 1.8V-so look carefully here.
Check resistor connected to pin9(TON). This should be high value resistor close to 500Kohms(Have'nt gone thru schematics)
This resistor often goes bad.

[jagiro84]

hey mcplslg123

you were right the resistor connected to pin9 is 499k 1%, measuring on PCB showed reading of around 240ish K, desoldering it showed 490k, some other resistors around the PUM1 have decreased their values as wel while measured on pcb, could the PUM1 be malfunctioning or is this normal? i have replaced those resistors just to be sure , but they too drop their resistance values once soldered on PCB


Pin 7 has 0v while OFF turned ON 3,38v (also noticed that pin 7 and pin10 would occasionally lose voltage in ON state from 3,38v to 0v while pin8 retain its 1.82v and pin 9 0.8v )
pin 8 has 0v while OFF, turned ON 1.82v
pin 9 has 19v while OFF and changes to 0.89 when turned ON
pin 10 has 0v while OFF, turned ON 3.38v

[mcplslg123]

Link schematic if available. Pin8 should be stable 3.3V after power on in my opinion.
The resistors will show different values when measured in circuit and thats why resistors always should be measured out of circuit-so its normal.

[jagiro84]

I only have the boardview, schematics are not available. If u need I can send you the boardview file just tell me how u want to have it.

What do u think about pin 6 that says FB_Pddr5. It's 0v at all times.

This is supposed to be feedback line

[mcplslg123]

You need to check whether the IC is powered,next whether enable's are present and then comes feedback. So focus on why pin8 is at 1.8V.

[jagiro84]

You need to check whether the IC is powered,next whether enable's are present and then comes feedback. So focus on why pin8 is at 1.8V.

Hey mcplsig, is it possible that the pin8 1.8v is normal?

i tried to analyse the PUM1 RT8231BGQW_WQFN20 datasheet through chatgpt , and i provided it with my own manual measurements on each of the pins, and considering i have LPDDR5 ram, chatgpt says 1.8v is normal voltage. is this an error on chatgpt part?

this is the table the chatgpt provided me with for each of the pins, with my own meassurments and what should be expected

[mcplslg123]

Link the schematic here. Can be confirmed by reading schematic. However, i've never seen enable at 1.8V on RT8231BGQW so far. So i still doubt it.
These enables are nothing but SLP_S3 and SLP_S5. This has nothing to do with ddr type.

[jagiro84]

Link the schematic here. Can be confirmed by reading schematic. However, i've never seen enable at 1.8V on RT8231BGQW so far. So i still doubt it.
These enables are nothing but SLP_S3 and SLP_S5. This has nothing to do with ddr type.

no schematic is available, only boardview file. i have send you personal message with the boardview file as i wasnt sure if i can share it here

here is a screenshot of the PIN8 S5_PDDR5 of PUM1 which connects to the PRM13 0_0402_5% on pin 2 and the Pin1 of PRM13 is connected to the 1.065v_mem_en network.

[mcplslg123]

NO pm received from you. You can post the boardview in schematic section and link it here.
PRM13 is 0 ohms? Voltage on both sides of it is same 1.8V?

[jagiro84]

NO pm received from you. You can post the boardview in schematic section and link it here.
PRM13 is 0 ohms? Voltage on both sides of it is same 1.8V?

yes its 0hms and voltage is same on both side, i manually measured it.

here is the boardview file for your review https://www.badcaps.net/forum/troubl...611p-boardview

[mcplslg123]

Exact resistance to GND on PLM2?

I'm still in doubt regarding voltage on pin8. Maybe its correct.

I dont have much idea to add on this issue.

If the resistance to GND on PLM2 is healthy, You can desolder this coil and inject 1.05V on pin2 of PLM2 from external source.

Are you sure, the ram replacement went smooth-no track damaged etc etc.

[jagiro84]

All pins on pum1 have a healthy resistance , only pin 16 and 19 of pum1 have low resistance, but this might be normal since they are connected to the plm2 coil going to LPDDR5 ram, the coil plm2 is passing the 1.055 voltage .

When I disconnect the pjpm1 jumper pad the voltage on coil is 1.06 and when I connect it back it is 1.055

Yes the pads before soldering new ram was all looking beautiful and clean. I took extreme care and time to make sure everything was done properly