820-2915 black screen after Tiresias?

[Anterweb]

Got what I thought is a classic 2011 15inch GPU issue.

Machine looks clean turns on and chimes but just shows a white screen

Removed board, disabled GPU by removing R8911 fitted Tiresias, pop board back in to test before adding brightness control wires and it turns on chimes back light comes on but all I get is a black screen, tried logic board in known good working second machine same result.

Is this a common issue, a dead Tiresias or maybe not a GPU fault in the first place?

 

[Anterweb]

I've also gone over the Tiresias solder joints twice and checked for shorts, the fitting is immaculate

 

[2informaticos]

In the first moment, did you get pure white, or classic Apple gray?
You can test reverting changes.

Just in case, do PRAM reset 2-3 times.

 

[Anterweb]

In the first moment, did you get pure white, or classic Apple gray? = Pure white

Put back R8911 and removed Tiresias ,

Now just getting the exact same behavior, Machine powers on, chimes I get back light but just a black screen,.
( Same on external monitor )

It also seems unresponsive to PRAM reset,I tried it a dozen times but I just get the single chime and backlight and no reboot or second chime it just hangs on this black screen with backlight no matter what I do like its hung until I force it off by holding the power button.

 

[2informaticos]

Pure white means no 3.3V going to LCD.
If you get black screen now, LCD should get that voltage; just check on video connector.

To discard a problem with Tiresias adapter, try disabling GPU in BIOS.
Don't forget to remove R8904/11 first.

 

[Anterweb]

can this be done with Medusa?

Iv just got one from Harold but not used it yet??

Don't forget to remove R8904/11 first. Is it not just R8911 I remove to disable GPU? This is the first I have seen R8904 mentioned

 

[2informaticos]

Removing one resistor is OK, but I prefer to remove both.
In fact, when I disable GPU, I remove and recover all MOSFETs and chip controllers from GPU power supplies.
There are also many filter caps to be reused.
First MUST confirm that board works correctly in UMA version.
For BIOS mod, I also recommend EFI password; as protection against PRAM reset.

Medusa has dedicated function to disable GPU for these boards.

 

[Anterweb]

So you recommend I first try this machine by disabling GPU with medusa.

When I received my medusa I got bunch of adaptors but it dosent come with any instructions or manual at all so I'm a bit lost with it..

Could you point me in the right direction for connecting it to this board and trying the feature you said it has

I do have a plie of Tiresias that I would like to use to preserve brightness control.

 

[2informaticos]

Medusa 3 (firmware 3.1) manual.pdf

drive.google.com

You can also try with another Tiresias module.
I doubt to have two with same problem.

 

[Anterweb]

Thank you, will give this a go

 

[Anterweb]

Removed R8911 again and tried a known good Triesas chip, same deal.

So now with or without the Triesas it powers on, fan spin, chime, back light kicks in, but no display.

Also unable to do any kind of Pram reset it just dosent respond

 

[2informaticos]

Try known good BIOS.
There may be EFI password...

 

[Anterweb]

Spent some time practicing with the medusa today, then used to put a good known bios and clean the ME on this one, put the Tiresias back on and boom, booted first time!

Can't tell you how good that felt and how easy that was with the medusa in comparison to removing the efi chip to re programme!


Worth every penny and thanks for the recommendation!

Thanks for your help dude!

 

[2informaticos]

Did test now if Tiresias works correctly?

 

[Anterweb]

Yes!

Re installed it and now it's installing Catalina.. Will add brightness jumper wires after all is good from os install

 

[Anterweb]

Iv'e got an 820-2914 here , It had a dead GPu and a damaged LCD connector, I replaced the LCD connector and added a Tiresias , I'm now getting boot up fan spins, chime and backlight, as the one in this thread above so grabbed my Medusa and realized I don't have a donor with known good bios I can pull so I download one from Badcaps,

Then realized I have no clue how to connect the Medusa to the pc to add the bios to the Medusa?
The manual is a bit vague and I cant seem to find any other info or videos explaining how I do this,
I know I connect the medusa in that small slot under the screen with either this black or blue cable I have with it but what do I connect it to?

Please help

 

[2informaticos]

Medusa comes with a DIP-8 adapter, to insert into any USB programmer.
The secondary slot (under the screen), connects directly with Medusa SPI ROM (8MB).

 

[Anterweb]

aHH PERFECT!

Got this set up now, But either I fked something up or the bios I got from Badcaps was crap.

Would you have a bios file I can try?

It not dosent chime or backlight just fan spin,,,

 

[2informaticos]

820-2914-A DV10-11 clean me no gpu.rar

drive.google.com

 

[Anterweb]

This is still giving me shit! but just clocked this board is a 820-2914-B not -A

Would this be a different bios?