820-00239-09 - A1706 continues chime sound

Before removing the motherboard I could see 20V and 2.80Ampere current. Continues to chime sound (Not very loud) when I open the lid. Sometimes (I think after SMC reset) I can see an apple logo coming and going without backlight.

I have removed the logic board the current/power consumption is 20V and 0.44Ampere (8.83W).
Here are the voltages
L3500 - P5VUSBC_X_R - 0V
L8410 - PPVOUT_S0_LCDBKLT -0V
L7030 - PPBUS_G3H - 13.11V
L7660 - PP3V3_S5 - 3.367V
C7651 - PP5V_S5 - 5.150
L7600 - PP5V_S4 - 5.153V
L7700 - PPVCCEDRAM_S0_REG_F - 1.056
L7430 - PPVCCGT_S0_CPU - 0V
L7420 - PPVCCGT_S0_CPU - 0V
L7410 - PPVCCGT_S0_CPU - 0V

L7210 - PPVCC_S0_CPU - 0.629V
L7220 - PPVCC_S0_CPU - 0.629V
L7270 - PPVCCSA_S0_CPU - 0.897V


L8000 - PP1V0_SUS - 1.028V
L7960 - PPVCCIO_S0_CPU - 0.959V
L7900 - PP1V2_S3 - 1.206V
L8050 - PPVCCPRIMCORE_SUS_PCH - 1.013V

Could someone please give me some advice on how to proceed further to diagnose and fix the issue?
History of this board: As far as I know someone changed the display, Maybe some nonprofessional person. This issue started from there,

Thanks in advance
Br
Manu
 
I have removed the LVDS cable from the internal display and tested it with an external monitor. After a lot of attempts, I could see an apple logo on the monitor for just 2 seconds, immediately it restarted. I think the HDMI needs some time for detecting it, before that it is restarting. The fans are not running while pressing the power button. Same time the CPU heat pipe also warm (Not too hot approximately 50 deg).
 

2informaticos

Administrator
Staff member
Disconnect Touch ID and test again.

If battery is charging, test the board on battery alone, without charger.
 

2informaticos

Administrator
Staff member
You should check for knocked of components; near the screw holes.
Also inspect all connectors for damage.
 
No, i don't see anything unusual near the screw holes, except the C8410 and C8412 caps broken, C8410 I have already replaced.Apart from that J6951 clip is broken, But still, there is proper contact on the pins. I don't think it is creating the problem.
Is there anything else I can try on this board?
 
I can see it is charger is supplying 2.80Ampere current when I connect the battery. Is there any other option I can make sure the battery is charging ?
 

2informaticos

Administrator
Staff member
Then J6951 has good contacts.

As you already found some broken components, inspect entire board under microscope.
 

2informaticos

Administrator
Staff member
"PPVCC_S0_CPU - 0.629V"
Is it stable, or fluctuates with each chime sound?

Try starting in SMC bypass, to see if board stays on.
 
Back to this board , PPVCC_S0_CPU is stable , I don't see fluctuation on any of the rails
L3500 - P5VUSBC_X_R - 0V
L8410 - PPVOUT_S0_LCDBKLT -0V
L7030 - PPBUS_G3H - 13.11V
L7660 - PP3V3_S5 - 3.367V
C7651 - PP5V_S5 - 5.150
L7600 - PP5V_S4 - 5.153V
L7700 - PPVCCEDRAM_S0_REG_F - 1.056
L7430 - PPVCCGT_S0_CPU - 0V
L7420 - PPVCCGT_S0_CPU - 0V
L7410 - PPVCCGT_S0_CPU - 0V

L7210 - PPVCC_S0_CPU - 0.629V
L7220 - PPVCC_S0_CPU - 0.629V
L7270 - PPVCCSA_S0_CPU - 0.897V


L8000 - PP1V0_SUS - 1.028V
L7960 - PPVCCIO_S0_CPU - 0.959V
L7900 - PP1V2_S3 - 1.206V
L8050 - PPVCCPRIMCORE_SUS_PCH - 1.013V
 

2informaticos

Administrator
Staff member
Did you test without battery, nor trackpad flex connected?
In fact disconnect internal LCD and check with external monitor only.
 
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