Display brightness of my old iMac

[Balsie]

That's correct, that's how I have it connected. What is the issue?
Thanks!

You should feed the Chinese board from the original PSU with + (pin 11,12 or 13) and GND (pin 1,3,5 or 9).
PS_ON (pin 6) must be connected with GND (pin 7) to turn on the PSU.
You can use a switch (no moment, like the original Mac on/off switch), but a permanent one to switch the PSU on/off.
My configuration is perfectly working, are you interested?

 

[SubDriver]

You should feed the Chinese board from the original PSU with + (pin 11,12 or 13) and GND (pin 1,3,5 or 9).
PS_ON (pin 6) must be connected with GND (pin 7) to turn on the PSU.
You can use a switch (no moment, like the original Mac on/off switch), but a permanent one to switch the PSU on/off.
My configuration is perfectly working, are you interested?

Agree with @Balsie and it is a good catch to notice that detail in your diagram. I assumed that was a typo or something since you stated you had followed my guide. Pin 6 is not a pin to supply power.

Anytime the power supply is plugged into an AC outlet, you will have power at Pin 4 and Pin 6. Neither of those are ideal to power the LCD driver board, especially Pin 6. As stated, you short Pin 6 to Pin 7 to turn on the rest of the power supply Pins and then use Pins 11, 12, or 13 to provide the 12Vdc to the LCD driver board.

I elected to use the 12Vdc lines from the driver board to connect to the step down voltage converter and the buck voltage regulator for my final build.

 

[Monja96]

I followed your advice and I finally got an image! Having the board connected with the PSU ON was a big mistake.

Right now, the screen seems a bit dim and, most notably, it's flickering a lot. What could be the cause?

 

[SubDriver]

I followed your advice and I finally got an image! Having the board connected with the PSU ON was a big mistake.

Right now, the screen seems a bit dim and, most notably, it's flickering a lot. What could be the cause?

View attachment 2503762

Please provide us with details of all the electrical connections. A new diagram would be useful.

Possibilities:
1. Loose connection between the LCD driver board and the screen
2. Loose connection to the inverter (either the PWM or the BLO/ENA)
3. Incorrect PWM setting
4. Poor quality BLO signal (essentially the BLO signal is turning on and off rapidly)
5. Something unknown

 

[Balsie]

I followed your advice and I finally got an image! Having the board connected with the PSU ON was a big mistake.

Right now, the screen seems a bit dim and, most notably, it's flickering a lot. What could be the cause?

View attachment 2503762

Sorry to hear that.
What is your duty cycle setting on your PWM?
Too high or too low may cause flickering, if you set it to 70 it should work.
The worst case scenario is, that your Chinese board is damaged.
You can test it with your Chinese inverter (if you still have it).
If that works you know the basic is working.
Let us know and good luck.