Dell Precision 3520 Troubleshoot

[Asxetos21]

I could use some help to troubleshoot an "almost dead" Dell Precision 3520 laptop (CDP80 LA-E152P board, Intel i7-7820hq cpu, Nvidia quadro m620 gpu) that started to die on me a few weeks ago.

Usually it will not POST, power button led stays on only for a few seconds with no other life signs. When the charger is connected it does the same, but the front battery indicator led slowly flashes white for ever (with or without any actual battery connected).

On very rare occasions it has POSTed, on one occasion i was even able to update the bios to the latest.

I took a bios flash dump and programmed some alternatives from around the net (for the specific board). Of course i have pulled the cmos battery during every flash, changed the cmos battery to a new one, tried a different main battery and memory, nothing new.

I can't find the exact schematic for my board, but found one for almost the same board (CDP81 LA-E153P), the only difference being it is missing the thunderbolt 3 circuitry that mine has (attached).

MOD EDIT: Schematic moved -> https://www.badcaps.net/forum/showthread.php?p=1252070

I am very experienced with electronics (not laptop motherboards unfortunately), so i thought i could use some pointers on what to check.

As a last resort i wouldn't mind even trying a cpu-gpu-chipset reflow if you think it could be the problem (cpu-gpu replacement is just uneconomical, i should as well change the whole board).

Thanks anyway...

[Techtiger]

Re: Dell Precision 3520 Troubleshoot

Take a pic of the MB mark all the Voltage of BIG Gray coil’s Example PL1302 ect .for no post be due to bad BIOS if not SOC solder joints or DC to DC line missing

[piernov]

Re: Dell Precision 3520 Troubleshoot

Is this out of warranty already?

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

Take a pic of the MB mark all the Voltage of BIG Gray coil's Example PL1302 ect .for no post be due to bad BIOS if not SOC solder joints or DC to DC line missing

Thanks techtiger, I'll do that and get back.
In the end i don't think its a case of bad bios. When it started, i was on the same bios for quite some time.
But like you, my first thoughts were 1. bios (hence the bios flashing) 2. SOC solder joints 3. something else...

Is this out of warranty already?

Thanks piernov, but i won't even go that way. The laptop is a "salvage". A dirt cheap liquid damaged one off Ebay, with a bargain motherboard again off Ebay. Not even the service tag's on the casing and the board match. Dell just does not cover these cases.

Good thing (in this case) about the latest Dell's is, they are single board designs. If you replace the mainboard, you don't worry about any secondary boards gone bad.


Thanks.

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

Ok, Here are some pictures and measurements...






COIL FUNCTION OFF ON

PL901 DC-IN 19,50 19,15
PL902 BATTERY - DC-IN SWITCH 3,06 13,50

PL201 DDR 1,2V SUPPLY 0,00 1,20
PL100 3,3V POWER RAIL 3,36 3,37
PL301 1V-SUPPLY 1,00 1,00

PL612 CPU GT ??? SUPPLY 0,00 0,00
PL613 CPU GT ??? SUPPLY 0,00 0,00

PL610 CPU CORE SUPPLY 0,00 1,08
PL611 CPU CORE SUPPLY 0,00 1,08
PL614 CPU SA SUPPLY 0,00 1,06

PL101 5V POWER RAIL 5,17 5,16

PL1301 GPU SUPPLY 0,00 0,89
PL1302 GPU SUPPLY 0,00 0,90
PL401 1V IO SUPPLY 0,00 0,98

PL1400 VRAM SUPPLY 0,00 1,34
PL1601 1,05V SUPPLY 1,05 1,04


The coil numbers are the same on my board and the attached schematic.
The measurements are with AC adapter only (no main battery attached). 2 measurements on each rail, the 1st is the OFF state, the 2nd is the (brief) ON state.

Something is wrong with the "CPU_GT" power rail? It does not change from off to on. (i think CPU_GT stands for the CPU on board graphics supply)...

Please advise, Thanks...

[mcplslg123]

Re: Dell Precision 3520 Troubleshoot

Flash bios as gfx core is missing. Ram stick is known good one??

[mcplslg123]

Re: Dell Precision 3520 Troubleshoot

If you have lab psu, consumption with ram and same without ram(after turning on)??

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

Flash bios as gfx core is missing. Ram stick is known good one??

The ram is tested good. Working fine on a second laptop (same generation), just checked again.
Gfx core missing? I don't think so. 3 different direct flash dumps for the same laptop reflashed should show some difference.

[mcplslg123]

Re: Dell Precision 3520 Troubleshoot

CPU_GT" power rail is missing-You said so.

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

By "gfx core" i thought you meant the bios part. I am just saying how can one "more" bios flash fix what looks like a hardware fault.

My feeling is it could more likely be a bad switching controller, a shorted or open switching fet, an open solder joint on the cpu, etc etc...

[mcplslg123]

Re: Dell Precision 3520 Troubleshoot

Gfx core will not rise if bios is at fault. thats why the advice to flash bios. As you have already flashed bios a couple of times but there is a probability that those bios were not good. I'll suggest you post your request for bios dump in bios section and post your original bios there as well. There are many experienced members here who may fix the corrupt bios. However, if the problem is not solved we can look into hardware issues at a later stage. its not proper to mess with hardware unless you are 100% sure that its a hardware issue. Thats my advice-rest is your choice.

[Techtiger]

Re: Dell Precision 3520 Troubleshoot

Check the Voltage requirements for PU612 PU613 VIN VDD ect , GXF CORE missing BIOS faulty

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

The voltages on the switches are OK. VDD 5.0V VIN 13,50V. But as always no power on the VCC-GT rail.
PS. The bin you gave me doesn't work. Same behavior...

Thanks...

[mcplslg123]

Re: Dell Precision 3520 Troubleshoot

Check DDR_DRAMRST# on ram slot.

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

check ddr_dramrst# on ram slot.

off= 0v
on= 1.2v

[mcplslg123]

Re: Dell Precision 3520 Troubleshoot

off= 0v
on= 1.2v

Thats perfect.

[SMDFlea]

Re: Dell Precision 3520 Troubleshoot

The voltages on the switches are OK. VDD 5.0V VIN 13,50V. But as always no power on the VCC-GT rail.
PS. The bin you gave me doesn't work. Same behavior...

Thanks...

Which switches do you mean, PU612 ,PU613 and PU614 .Do you have IMVP_VR_ON on PU601

[Asxetos21]

Re: Dell Precision 3520 Troubleshoot

Which switches do you mean, PU612 ,PU613 and PU614.

I mean PU612 and PU613 which control the missing VCC_GT. PU614 is for VCC_SA which rises fine.

Do you have IMVP_VR_ON on PU601

It will take some time to trace the signal on the board and measure it, but to me, it must be working.
Per the schematic, PU601 controls ALL CPU voltages (VCC_CORE, VCC_GT and VCC_SA).
If IMVP_VR_ON was missing, none of the 3 voltages would rise. But as measured, VCC_CORE and VCC_SA rise just fine...

Searching, I measured PWM1_VCORE and PWM2_VCORE on PU610-PU611,
and compared it with PWM1_GT PWM2_GT on PU612-PU613
On the working rail (VCORE) it settles to 0.3-0.4V.
On the missing rail (GT) it is A-LOT higher to 1+V.

(sorry i don't have a logic analyzer, just a multimeter)

Probably the controller (PU601) receives no feedback and increases PWM duty-cycle to raise a voltage that never comes-up.

So i am suspecting PU612-PU613. Even though they are powered, they do not switch-on.

[kiraro]

Re: Dell Precision 3520 Troubleshoot

try the dis->uma conversion if exist (fast way to eliminate graphic chip problem)remove some jumper or coil for graphic controllers , in this case if there is any problem related to the graphic Chip you will see post, I have similar problem with other model and finally it was graphic issus not bios . hope that help you.
here are the schematic for uma version with similar model CDP80 LA-E151P REV 0.2 UMA
compare with and remove jumper or power rail for graphic chip .

MOD EDIT: Schematic moved -> https://www.badcaps.net/forum/showthread.php?t=120899
.

[SMDFlea]

Re: Dell Precision 3520 Troubleshoot

Can you check PR680,and resistance on pin 8 PU612,PU613.