Display brightness of my old iMac

[Balsie]

Take a penny. Leave a penny.

I managed to use the original apple inverter board for full brightness control together with the chinese control board.

In this scenario the chinese inverter which comes with the controll board is not used.

The pins are basically described on both boards.

From the China control board the ADJ goes to PWN and the BL_ON to the BL_ON of the Apple inverter. Furthermore, the 12 V pins and the GND pins are connected to the respective 12 V pins and the GND pins on the Apple inverter.

The brigthness can also be regulated via the menu of the Chinese Controller board. However, the adjustment bar in the menu is now strangely inverted. So that the maximum screen brightness corresponds to 0% at the adjustment bar of the brightness in the menu.

The maximum brightness should be a voltage of 3.25 V. I was also able to measure this with the multimeter.

Everything works for now. Let's see if it stays stable when the screen is on for several hours.

I have used a iMac 2010 with a LG LM270wq1 SDC2 Screen. I orderd the Control Board Version with Display Port and HDMI

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14,19€ | DP_HDMI Zu EDP Stick bord LM270WQ1-SDC2/LM270WQ1-SDA2/LM270WQ1-SDE3 Control board Kit für 2560X1440 LCD LED Screen

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Further I have used a 12V 5 A Power supply.

Hello, I bought a (working) iMac 27 inch 2009 for 50 euro with a beautiful lcd-screen (no spots or something like that).
I intended to use the original PSU and inverter.
I measured the pin-outs and soldered everything together with the Chinese MB.
The Chinese MB works (green led) and measured the power on the psi.
But nothing happened on the screen and I hear a high pitched sound from the inverter.
I hope someone can advise me (excuses for my English, I'm Dutch).
By the way: first I tested the Chinese MB with the Chinese inverter and that works.

 

[davevsxe]

Hello, I bought a (working) iMac 27 inch 2009 for 50 euro with a beautiful lcd-screen (no spots or something like that).
I intended to use the original PSU and inverter.
I measured the pin-outs and soldered everything together with the Chinese MB.
The Chinese MB works (green led) and measured the power on the psi.
But nothing happened on the screen and I hear a high pitched sound from the inverter.
I hope someone can advise me (excuses for my English, I'm Dutch).
By the way: first I tested the Chinese MB with the Chinese inverter and that works.

Hi all,

As described at the time, I used the original Apple inverter board from the iMac2010. However, I powered it by the China board.

I did not use the Apple PSU. As far as I know, an additional signal had to come from the iMac motherboard in order for the Apple PSU to drive the Apple inverter. So you may be missing this signal.. However, I'm not entirely sure about this, since I have not used the original PSU.

I used Wago Clamps to test my wiring. Then you don't have to solder everything directly. It was actually quite simple.

If you want to use the original PSU, try a step-by-step approach and try to drive the Apple inverter with the China board first.

My wiring:

China Inverter	Apple Inverter
12V	12V
12V	12V
ADJ	PWN
BL_ON	BL_On
GND	GND
GND	GND

I will try to make a video / some pictures of my wiring soonish…

 

[Balsie]

Hi all,

As described at the time, I used the original Apple inverter board from the iMac2010. However, I powered it by the China board.

I did not use the Apple PSU. As far as I know, an additional signal had to come from the iMac motherboard in order for the Apple PSU to drive the Apple inverter. So you may be missing this signal.. However, I'm not entirely sure about this, since I have not used the original PSU.

I used Wago Clamps to test my wiring. Then you don't have to solder everything directly. It was actually quite simple.

If you want to use the original PSU, try a step-by-step approach and try to drive the Apple inverter with the China board first.

My wiring:

China Inverter	Apple Inverter
12V	12V
12V	12V
ADJ	PWN
BL_ON	BL_On
GND	GND
GND	GND

I will try to make a video / some pictures of my wiring soonish…

Hi, thanks for you reply.
I've done the way you wrote, but unfortunately no result.
This afternoon I'm going to connect the Chinese inverter again to the Chinese mb.
I only have one question: on CN6 I can switch the jumper between R28-R116-R27-R25.
On the backside of print these R's are representing 10V-12V-5V-3.3V.
Can you you tell me your setting of this jumper?
Thank you in advance, kind regards.

 

[PaulD-UK]

Quote @Balsie: "
"...on CN6 I can switch the jumper between... ...10V-12V-5V-3.3V."

Here is a data sheet translation for setting that jumper:
"Installation notes; 1-1 In the production process, the operation order is to first connect the signal line and the control line, (check whether the screen voltage jump cap is correct, there are 12V/10V/5V/3.3 channels) check that the connection is correct before powering on."

So the jumper determines the output voltage supplied to the screen backlight driver electronics.
Different screens used with these boards in China require different voltages.
Later Macs use the 12v setting, so I expect ithat's the same for 2009-11 era iMac screens?

 

[Balsie]

Quote @Balsie: "
"...on CN6 I can switch the jumper between... ...10V-12V-5V-3.3V."

Here is a data sheet translation for setting that jumper:
"Installation notes; 1-1 In the production process, the operation order is to first connect the signal line and the control line, (check whether the screen voltage jump cap is correct, there are 12V/10V/5V/3.3 channels) check that the connection is correct before powering on."

So the jumper determines the output voltage supplied to the screen backlight driver electronics.
Different screens used with these boards in China require different voltages.
Later Macs use the 12v setting, so I expect ithat's the same for 2009-11 era iMac screens?

I've tried all the jumper-settings without any result, so I've put him back to 12V.
It was a pity, that I could not use the Apple inverter.
Now it's back with the Chinese inverter and that works.
I have to deal with it and I can live with the "less" brightness.
I think there's no other solution, thanks for the support.

 

[Balsie]

I've tried all the jumper-settings without any result, so I've put him back to 12V.
It was a pity, that I could not use the Apple inverter.
Now it's back with the Chinese inverter and that works.
I have to deal with it and I can live with the "less" brightness.
I think there's no other solution, thanks for the support.

I've tried all the jumper-settings without any result, so I've put him back to 12V.
It was a pity, that I could not use the Apple inverter.
Now it's back with the Chinese inverter and that works.

I've tried all the jumper-settings without any result, so I've put him back to 12V.
It was a pity, that I could not use the Apple inverter.
Now it's back with the Chinese inverter and that works.
I have to deal with it and I can live with the "less" brightness.
I think there's no other solution, thanks for the support.

One final question: what are your institutions in the menu (like brightness and backlight)?