820-3299

raainxx

Member
Hi,
i have this imac with only one led1
i find some component broken like R5335, U5420, U9720 (when i remove this last PP5V_S0 in diode mode 0,020 became 0,250)
for the last i can't find the reference REF3333, is not the reference i think.
i would like to find in other board but when i search this ref, i find a lot of board but not this component.
Do you have an idea where can find it?
I think the SSD kill the board or the board kill the SSD, because he don't work.

i try without U9720 but all no PP5V_S0, is it normal?
 

2informaticos

Administrator
Staff member
PP12V_S0_FET pulses at least?
I saw Q7950 leakage issue sometime.

Check if PM_SLP_S4_L pulses when you trigger SMC_ONOFF_L.
 

raainxx

Member
no pulse PP12V_S0_FET & PM_SLP_S4_L when i push on the power button
I check the signal SMC_ONOF_L fall down when i push the button.
 

2informaticos

Administrator
Staff member
Then all PM_SLP_Sx_L signals should pulse at same time; if not is PCH issue.
However, check first if PCH gets all (other) signals required for power on sequence.
 

raainxx

Member
ok i have no pulse on all PM_SLP_Sx_L. i think it's power sequence problem.
I try to find it this day. i have a question for power supply, can i use a external power supply and apply 12V on the board? without the real supply because it's hard to check signal on the iMac.
thanks
 

raainxx

Member
finally i check power sequence like this example

G3H/RTC rails + 32kHz RTC clock → {SRTCRST, RTCRST, INTVRMEN, INTRUDER#, DSWVRMEN} → S5 rails → S5_PWRGD → DPWROK → SLP_SUS# → SUS rails → RSMRST# → BATLOW# → PWRBTN# → SLP_S5# → SLP_S4#

Some signal are not present on this board. all seems good befor SLP_S5 but no PM_SLP_S5_L & PM_SLP_S4_L signal
maybe a bad U1800? is it possible?
 

2informaticos

Administrator
Staff member
We talk about Apple board, why do you write "#" here?

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.
 

raainxx

Member
sorry i copy just a start sequence find on a website.
PM_PWRBTN_L fall when i short SMC_ONOFF_L, i tell you on previous message :)
 

2informaticos

Administrator
Staff member
If PCH gets all the signals required, then is bad; if yuo cannot get any pulse at PM_SLP_S4_L.
I recommend you to use an o-scope; it can catch any fast peak pulse.
 

raainxx

Member
i use an tektronix tbs 1102B and i don't see anything on PM_SLP_S4_L.
Garbage or try to change U1800 by donor?
thanks
 
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