Toshiba L750 DABLBDMB8E0 UMA enable

[vannix]

Hi all, i have some problems converting this notebook from nvidia graphics to intel hd.
In schematic i found 2 resistor to change (attached pictures), but R197 is NOT present.
Adding R196 and swapping R560/R538 nvidia card seems disabled but i can't enable the intel vga. the notebook boot, the backlight is on but there is no signal on display (internal and external) and no vga card is detected under os.


searching with google i found this zip, but i can't download it..
https://rom-bios.com/threads/toshiba...ete-to-uma.33/


can someone help me?

thank you in advance

[KvnTM]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

Only populate R538 to pull ID1 High as stated in the chart to enable UMA.
R196 has to be present & R197 has to be removed to enable UMA.

Are you 100% sure that your board has the Nvidia gpu populated? Post a picture of your board.

EDIT: Please attach the schematic. I don't want to register on another forum.

[vannix]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

R196 and R197 are not populated by default, and i'm sure that there is a nvidia geforce 525. with a little reflow i was able to boot ubuntu from command line, in lspci (list all pci devices) i see nvidia vga controller (geforce 525m) and one nvidia hd audio controller (hdmi). but there isn't any intel vga controller..


pics and schematic as attached

[KvnTM]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

R196 and R197 are not populated by default, and i'm sure that there is a nvidia geforce 525. with a little reflow i was able to boot ubuntu from command line, in lspci (list all pci devices) i see nvidia vga controller (geforce 525m) and one nvidia hd audio controller (hdmi). but there isn't any intel vga controller..


pics and schematic as attached

First replace that NEC TOKIN Proadlizer under the CPU Socket with 4x 330uF caps. The NEC TOKIN will fail at some point. Has nothing to do with disabling the nvidia gpu but just do it. trust me. Other people on the forum will confirm this.

What was the original problem with the nvidia gpu? These are not known to cause any issues.

If you want to change the board to UMA just do what I said:
Only populate R538 to pull ID1 High as stated in the chart to enable UMA.
R196 has to be present & R197 has to be removed to enable UMA.

I'll take a look at the schematic though.

[vannix]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

i know nec tokin, already replaced in many other PCs, but this notwbook has not that problem..
it boot normally but the screen is black. pressing the gpu the screen flicker, and reflowing it will show image, so the only way is change/reball or disable.

If you want to change the board to UMA just do what I said:
Only populate R538 to pull ID1 High as stated in the chart to enable UMA.
R196 has to be present & R197 has to be removed to enable UMA.

this solution is not working, i already tried it before open the topic.
as i wrte in 1st post, the only difference is that i see a white display with colored lines, and the nvidia gpu is not recognized by os (tested from ssh)

probably this happen because the intel vga is disabled, but how to enable it?


for the schematic.. page 9 is board id settings, page 29 ec settings

[KvnTM]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

The best solution would be reballing the gpu.
Just replace the nec tokin. It hasn't failed yet but it certainly will.

As for your schematic... Ignore my recent post. My PDF program messed up opening it and opened another schematic form another board. Excuse my stupidity I edited the post to avoid confusion.

I'll take a look at it.

[KvnTM]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

Just as the schematic tells:
R538, R196 have to be populated & R560, R197 have to be removed.

That should be it.

[vannix]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

don't worry about the pdf

however the only result by adding and removing those resistor is the one you see in the attachment, and there isn't any vga controller detected


i'll search an used board for a few euros, possibly without a dedicated GPU

thank you anyway

[mcplslg123]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

Try the method as in attached pics. I've not tested it so not sure it works or not. Technically , I agree with @kvntm's advice.

[KvnTM]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

don't worry about the pdf

however the only result by adding and removing those resistor is the one you see in the attachment, and there isn't any vga controller detected


i'll search an used board for a few euros, possibly without a dedicated GPU

thank you anyway

I studied the schematic for a bit and it looks like the board doesn't have switchable graphics. Take a look at the LCD_TXLOUT data lines to the lcd panel. They directly go into the nvidia gpu without any multiplexer inbetween.

Also take a look at the CPU in the schematic. All FDI & eDP lines are not connected. So there is no way for the cpu to transmit image data to the screen.
Pretty sure the UMA version has a different board layout.

[vannix]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

Try the method as in attached pics. I've not tested it so not sure it works or not. Technically , I agree with @kvntm's advice.

thank you, but i already found those pics, the first one only disable the gpu power (but the power good signal go bad, and the notebook shut down)
the second picture is from another board

I studied the schematic for a bit and it looks like the board doesn't have switchable graphics. Take a look at the LCD_TXLOUT data lines to the lcd panel. They directly go into the nvidia gpu without any multiplexer inbetween.

Also take a look at the CPU in the schematic. All FDI & eDP lines are not connected. So there is no way for the cpu to transmit image data to the screen.
Pretty sure the UMA version has a different board layout.

you're right, now that you told me i saw it too.
Indeed i did't find any uma board with the same model/layout. i'll search some similar or compatibile one.

[KvnTM]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

Either that or properly reball the gpu. The chip itself is most likely fine.

[shajivc1]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

yes 100% correct

[mahroof]

Re: Toshiba L750 DABLBDMB8E0 UMA enable

for disabling nvidia gpu did you removed COIL PL10 on the board