Dell Latitude 3390 short on power adapter.

[Andreasbest]

With 1v and 1a it tops, same with 2A or 3A.
I don't want to go beyond this as the risk of burning the copper trace is very high.

[Sephir0th]

With 1v and 1a it tops, same with 2A or 3A.
I don't want to go beyond this as the risk of burning the copper trace is very high.

This is a Invalid argument, considering that you can't notice anything so far. More Amps is no problem. But more voltage might or might not turn the board into a no-fix.

When it takes 3Amps and nothing to spot, raise the Amps. When it takes 4Amps and nothing to spot, raise the Amps, and so on.

[Andreasbest]

Are you sure my friend?
I'm not sure so thin copper trace can handle 4 or 5A.

[Sephir0th]

Are you sure my friend?
I'm not sure so thin copper trace can handle 4 or 5A.

My friend, I don't want to make a showroom for myself here, but I probaby need to convince you that i am experienced on chip-level, working at this level for 4 years, running a repair business, and running a YT-Channel.

And without logical conclusions, you can't be succesful.

It is simple: if the tracks would be a issue here, they would already light up like a new year fireworks. But they don't, no?

I don't know how and from where you learned about these things, but voltage injection can not be seen as a static procedure. You always have to adapt to the circumstances.

So you have two choices now. Either you continue to mistrust my instructions and therefore continue to go round in circles. In that case, I won't pursue this case any further... OR you implement the instructions immediately.

The truth is, either the observations or the measurements must be wrong, otherwise we would have made progress long ago.

[Andreasbest]

Well regarding progress i feel it too, the shorted cap should have be visible with thermal camera but it isn't!

I'll take a couple of photos with the thermal camera of both sides with 1v 4a amd upload


Perhaps i miss something.

[Andreasbest]

Ok so with 1v and 5a a small cap became a little hot, without thermal camera it would be impossible to track it.

All good and laptop power up and charges battery as well, the problem now is that integrated screen doesn't light up, with HDMI i get image juat fine.

I'm not sure if it's only the backlight or the complete screen since the digitizer is not helping me to see clearly if there is image on dark screen or nothing at all.

Only i can see is that screen has some reaction when i power up the laptop (like it's trying to light up momentarily) but unsuccesfully.
What do you suggest?


Thank you for everything!
Great technician

[Sephir0th]

Sounds like "Backlight: Yes, Picture: No". Which is neither a expected nor a good outcome.

share a clear picture of the connector on the mainboard, without cable plugged. Don't forget to remove all power before unplugging the cable.

Then connect the display cable again and look for voltages at DCBATOUT_LCD, LCDVDD, BLON_OUT_C and LCD_BRIGHTNESS

[Andreasbest]

Hello!
DCBATTOUT_LCD 19v
LCDVDD 3.3v
BLON_OUT 0v (not sure if i measure the correct number 30 pin so i measure all around, all 0v)
LCD_BRIGTHNESS 0v too

[Andreasbest]

Checked R2043 resistor
0KΩ with no power.
3,3v with power and pressing power button. 3.3v on one pin, the other pin is 0v

[Sephir0th]

No BLON_OUT is likely the issue here. Make sure RN5501 is not internal shorted and that D5503 has not failed too. Clarify whether R5512 is present on the PCB and measure resistance to GND of RN5501 Pin 2 & 7 and of D5503 all pins.

Could be EC fault with some luck or something missed from visual observation.

[Andreasbest]

No shorts on RN5501 and D5503, checked all combinations.
R5512 not present.

RN5501
pin2 to GND 10KΩ
pin7 to GND 18.3ΚΩ

D5503 to GND attached

[Andreasbest]

Bump

[Andreasbest]

Bump

[Andreasbest]

Bump

[Andreasbest]

Still no image / backlight on integrated screen.
I'm on a dead end, can someone help please?

[Andreasbest]

Update for 3390 owners.

After some months today i reveived a fully working 3390, i tried to trace the source of the problem and i swapped motherboards, in my surprise my mb was working great, so i decided to disassemble screen, then i noticed the LVDS cable on the screen was half way unpluged, probably due to the 360 rotation screen, i firmply plug it and now it's working great.
Then i disassemble the customer's fully working 3390 and the LVDS was there unplugged too but was making contact and still working, i firmly plug it too.

Verdict: LVDS screen cable from 3390 2 in 1 are getting unplugged on it's own, check it before order screen or motherboard.
Thank you!