dell 3521 screen light on but no data

[mo000]

the laptop turn on with only screen backlight but without data .
and makes beeps ; one big beep and 7 others
but sometimes after i clear cmos by take cmos battery out the laptop work normally

i try to change the cmos battery and flash bios and ec and the same problem .

[KvnTM]

Re: dell 3521 screen light on but no data



Most Common Fixes:
1 Beep: Replace the motherboard / system board.
2 Beeps: Reseat the memory or replace the memory.
3 Beeps: Replace the motherboard / system board.
4 Beeps: Reseat the memory or replace the memory.
5 Beeps: Replace the CMOS battery.
6 Beeps: Reseat or replace the video card or replace the motherboard / system board.
7 Beeps: Reseat or replace the CPU.
8 Beeps: Reseat the LCD cable or replace the LCD screen.

Found on:
Dell Inspiron 15 (3521) Beep Codes Diagnostic Indicators

According a video it has something to do with UZ1.
I'll try to get a schematic and get back to you.

EDIT:
I attached 2 schematics. One for r1.0 and one r.04. Check your board markings for the correct one.
Take a look at UZ1 and measure for +1.5V and +1.5VS. This seems to be a known failure point. Replace UZ1 if +1.5VS is missing.

One little sidetone:
Don't flash EC/Bios out of the blue if you don't know what's going on. Always look at power rails first.

[mo000]

Re: dell 3521 screen light on but no data

Most Common Fixes:
1 Beep: Replace the motherboard / system board.
2 Beeps: Reseat the memory or replace the memory.
3 Beeps: Replace the motherboard / system board.
4 Beeps: Reseat the memory or replace the memory.
5 Beeps: Replace the CMOS battery.
6 Beeps: Reseat or replace the video card or replace the motherboard / system board.
7 Beeps: Reseat or replace the CPU.
8 Beeps: Reseat the LCD cable or replace the LCD screen.

Found on:
Dell Inspiron 15 (3521) Beep Codes Diagnostic Indicators

According a video it has something to do with UZ1.
I'll try to get a schematic and get back to you.

EDIT:
I attached 2 schematics. One for r1.0 and one r.04. Check your board markings for the correct one.
Take a look at UZ1 and measure for +1.5V and +1.5VS. This seems to be a known failure point. Replace UZ1 if +1.5VS is missing.

One little sidetone:
Don't flash EC/Bios out of the blue if you don't know what's going on. Always look at power rails first.

8 beeps lcd failure
but i change the screen and same problem
if 1.5vs missing the laptop turn on with black screen no backlight .
the 1.5s is found and in this time the laptop seems works fine but the problem maybe appears in anytime .

[KvnTM]

Re: dell 3521 screen light on but no data

Don't count the long beep. So you got 7 beeps.

Does magically work again?
I don't really understand what you are trying to say..

[mo000]

Re: dell 3521 screen light on but no data

Don't count the long beep. So you got 7 beeps.

Does magically work again?
I don't really understand what you are trying to say..

yes the laptop works fine but honestly i don't know how .

[mcplslg123]

Re: dell 3521 screen light on but no data

7 beeps problem wont go away automatically. If it is 8 beeps problem and you are getting display on a couple of occassions , then very likely your lvds cable is somewhat broken.

[mo000]

Re: dell 3521 screen light on but no data

7 beeps problem wont go away automatically. If it is 8 beeps problem and you are getting display on a couple of occassions , then very likely your lvds cable is somewhat broken.

yes i think so .