820-00034-A 2 led on, fan on, no chime/screen

yair37

Member
U7600:
same:
17-REG_VIN_U7600 11.6V
18- PP5V_S5 5V
4-REG_VCC2_U7600 5V
5-REG_VCC1_U7600 5V
24-PM_EN_REG_P5V_S4_R 0.01V diode mode 450
12-PM_EN_REG_P3V3_S5_R 3.8V
 

yair37

Member
6- REG_3V3_S5_FSET 2.7V
2- REG_P5VS4_FSET 0V
1-PM_PGOOD_REG_P5V_S4 0V

suddenly i get LED #1 and L7610 3.4V but no LED #2
 

yair37

Member
ISL62383C replaced.
U7600:
17-REG_VIN_U7600 11.6V
18- PP5V_S5 5V
4-REG_VCC2_U7600 5V
5-REG_VCC1_U7600 5V
24-PM_EN_REG_P5V_S4_R 0.01V diode mode 450
12-PM_EN_REG_P3V3_S5_R 3.8V
1 led on, when i press power button the led is of for 1sec and on again
 

2informaticos

Administrator
Staff member
Do you note drop pulse at 12V_S5 when first LED goes off?
You should change Q6970, just in case.
 
Last edited:

2informaticos

Administrator
Staff member
Possibly, compare specifications with the ones you have on scrap boards.
AON7402/08 and many other should work; not from Apple stuff.

Just try making a bypass D-S on it.
 

yair37

Member
yes i use the original power supply that come with this iMac.
to try with PSU anyway? and to connect directly to J6900?
 

2informaticos

Administrator
Staff member
I suspect knocked off components, or broken trace; if board stopped to turn off after ultrasonic bath and other tests.
 
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