Acer 5750, packard B TS11, la-6901p no display

[hansie55]

Hi guys,

I bought a Packard Bell TS11, which have the same motherboard as the Acer Aspire 5750 which is the LA-6901p.
I received it wit the folowing problem: No display on lvds, display on HDMI
Somehow the jlvds1 connector get shorted and the coils L1 and L2 got blown away, including the pcb islands. In the schematic you see the both are drawn in a separate section op page 31, W=60 mills.
I fixed the board as good as possible, but I do not know if from these islands something is connected to another layer (I don't see any signs) and I miss one coils.
Do I need this to get a display?

Can somebody pls direct me how to approach this problem. I was very happy to buy this laptop, given the specs, but now I'm afraid it might be onsolvable.

[dj_ricoh]

Re: Acer 5750, packard B TS11, la-6901p no display

does it power up?
what voltage do you got on the lvds connectorr?>

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

Thanks for the reply.
It does power up, works normal via HDMI.
Need to check voltages on lvds. wil come back opn that

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

Voltages on lvds connector.
pin 1,2,3, invpwr B+ = 18,80V
pin 7, invtpwr = 3,32V
pin 23, +3VS = 3,32V
pin 24,25 LCDVDD = 3,32V

Those were the results .......

pin6, bkoff = 3,3V

[dj_ricoh]

Re: Acer 5750, packard B TS11, la-6901p no display

ok!
do you see DAC_BRIG pin 26
I see you did not put the value.
its 0? maybe we can trace it back!

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

DAC_BRIG pin 26 gives 0

Finally find them:
Schematics for V2.0, which is the version of the board

[dellxps15]

Re: Acer 5750, packard B TS11, la-6901p no display

if you put a light on lcd can u see image ?

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

Thanks for reaction.

no image


Correction,

I switched the lcd for a surely good one and I do have a picture without backlight. Seen with lantarn behind it.

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

By the way, I did above voltage measurements with no lcd connected. Should it be done with the lcd?

[dellxps15]

Re: Acer 5750, packard B TS11, la-6901p no display

with or without should be the same.

chip u20, kb controller. pin 105 voltage with pc powered off and then when turn on.

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

U20 pin 105 powered off 0,0V . powered on 3,31V

[dellxps15]

Re: Acer 5750, packard B TS11, la-6901p no display

page 31 of schematic. check
bkoff line ;
capacitor C8 is if ok (no short and voltage 3.3 present at one side.

resistor R18, if voltage present both side and resistor value. should measure 10k (when pc is off).

check also chip u20 pin 68 DAC_BRIG if 3.3 volt are present.

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

U20 pin 68 powered off 1,10V and powered on 0,00V

Do you have a way to find the components, because most of the C's and R's are not printed on the PCB, see picture above



Think I found them, both is from pin 6 of jlvds1 to ground.

C8 no short, 3,31V at power on
R18 , 9,87k , 3,31V at one side and 0,00 at the other side (=gnd?)

[dellxps15]

Re: Acer 5750, packard B TS11, la-6901p no display

dac_brig if 0volt give max bright to lcd when inv power is ok.
when dac_brig is 3.3 it give low bright so 1.1 is in the middle and is ok.

the command that turn off the lcd is that bkoff. if 3.3 volt are present it power off lcd.

for me or a bga video problem, or dunno what component sent the signal to switch the lcd off. kb controller commanded by keyboard combination or hdmi is present signal ?

edit to trace that c8 and r18, look at pin 6 of lvd connector, and found them. one resistor and one capacimeter and i suspect they are ok, as the signal start from chip u20 .

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

HDMI works fine as far it starts up. Will try full use

see my edit in previous reply.

On page 31, above jlvds , the W=60mills drawing, L1 and L2 are missing from the board. Do I need those parts for proper operation?

[dellxps15]

Re: Acer 5750, packard B TS11, la-6901p no display

HDMI works fine as far it starts up. Will try full use

see my edit in previous reply.

On page 31, above jlvds , the W=60mills drawing, L1 and L2 are missing from the board. Do I need those parts for proper operation?

i mean if u remove hdmi and press some keyboard combination for lcd switch, u still have black screen ?

l1 and l2 if missing maybe they were not in use.

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

I have the Motherboard built out so the HDMI and the keyboard are disconnected.

I got the laptop with L1 and L2 exploded and a some part of pcb islands came of.
I cleaned the pcb board but the parts are missing. Are C9 and C6 the other 2 close to C8
and R18?

[hansie55]

Re: Acer 5750, packard B TS11, la-6901p no display

I think I have to put back L1 and L2, because now I do not have +INVPWR_B+ anymore on jlvds1--1,2,3,.
Do I have to use the precise same ones or can I use any kind?

[cyberhack]

Re: Acer 5750, packard B TS11, la-6901p no display

L1 L2 are the inverter supply if they are missing then no inverter ok page 35
link them out

[dellxps15]

Re: Acer 5750, packard B TS11, la-6901p no display

L1 L2 are the inverter supply if they are missing then no inverter ok page 35
link them out

didnt notice that l1 and l2 got bown away and when he said that lvds pin 1-2-3 volt 18 ok i thouth that they were some missing coils, but in the schematics they are 0805 component . u need to get them and put them back as cyberhack say .