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Real 747-400 ACP cannon plug

Started by Blake H, Thu, 16 Apr 2015 10:21

b744erf


b744erf


b744erf

Hello John. Would you please help to check which pins to make a Light-Test? (MD&T)
I saw the post said the pin 21 is 28V+ and 22 is Ground. I think there should be one pin is for the ground test when it connecte the ground. Thank you.

fsam

Hi, found pin 24 for lamp test. Best regards

John H Watson

Correct. Pins 23 and 24 should be for MD&T. 28 volts (and dim) power on 23. Lamp test on 24.

b744erf

Thank you Fsam and John.
Just to final confirm the wiring:

1/2      - Backlt
21       - 28v DC
22       - Gnd
15/16/17 - PTT switch

23       - 28v DC ?
22       - Ground for Lamp test?

Is that correct? But I still confused about the pin 23 and 21. Are they both connected to 28v DC? What are the differences?

And, in theory, to communicate the OEM ACP with PSX, we need to figure out the data in and out at pin 10-14 right?

I still don't understand how the data pins work:

"12 and 13 seem to be a clock signal (with the schematics assigning a "+" sign to pin 12 and "-" sign to pin 13 (In the wiring diagram, pin 13 is labelled as the "return"). Pins 13 and 10 also form a pair and are labelled as the input to the ACP).
Pin 10 is labelled "-" (but also "data in", on the wiring diagram) Pin 11 is an output (back to the AMU). Pin 14 is an earth inside the ASP as part of the shielding for the data lines. I don't know if 11 and 13 form a pair." by John.

Regards
Jack

John H Watson

Quote from: b744erf on Tue, 14 Nov 2023 08:45But I'm still confused about the pin 23 and 21. Are they both connected to 28v DC?


21 is panel power (from the Audio Management Unit). The panel filters and regulates 28vdc power (and produces +5v and +11v for internal circuitry)
22 is a power supply earth
23 is a two level voltage (bright and dim) from the MD&T system for button illumination. 28 volts and 12 volts

15 is an earth for the PTT keylines
16 is R/T
17 is INT

I don't know anything about the data processing in the control panels other than what is written in the basic overviews in the manuals:


















b744erf


b744erf

#28
Quote from: John H Watson on Tue, 14 Nov 2023 02:44Correct. Pins 23 and 24 should be for MD&T. 28 volts (and dim) power on 23. Lamp test on 24.

Sorry I come and ask the pins again. I did the power supply as you said and the light are on as a test mode. But it seems a little bit wired.

Situation A:
Pin21-28v DC, Pin22-GND, all lights are off. I can't test if the ACP is powered or not. But I believe it is ON already.

Situation B:
Pin22-GND, Pin21-28vDC, Pin23–28v/12vDC, all LAMPS are on in full brightness or dim, but LEDs is not illuminated. (Pin24 is not grounded)

Situation C:
Pin24-GND, Pin23–28v/12vDC, all LAMPS are on in full brightness or dim, but LEDs is not illuminated. (Pin21 is not powered. Pin22 is not grounded)

Situation D:
Pin22-GND, Pin21-12vDC, Pin23–28v/12vDC, all LAMPS are on in full brightness or dim(Pin24 is not grounded)

It seems that the light-test-mode will be active no matter the Pin24 is grounded or not or even the ACP is not powers... So how could I power up the ACP with 28vDC and give a 12vDC sim light power supply without light-test-active?

Thank you my friends!

Jack

John H Watson

Quote from: b744erf on Sun, 26 Nov 2023 08:16It seems that the light-test-mode will be active no matter the Pin24 is grounded or not or even the ACP is not powers... So how could I power up the ACP with 28vDC and give a 12vDC sim light power supply without light-test-active?

I don't know what component is responsible for normally lighting up the MIC lights. It may be the audio panel or it may be the Audio Management Unit card. As you know, when you push one transmit button, the  button that was previously selected extinguishes. Does pushing the button send a signal to the AMU which then illuminates the MIC light and extinguishes the previous selection?

You would have to ask someone who has used a real ACP.


Do you have more than one ACP? Are they all behaving the same?

b744erf

Yes. I do have all three  ACPs. And they behave exactly the same.