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820-00165 green light no power

I

iFix

Member
Hi guys.

I have this 820-00165 board no green light missing PPBUS_G3H. Someone played around with smc so i resoldered it. I also replaced U7501, there was a missing backlight IC i've soldered a new one and also replacedU7100. I finally managed to get a green light but no power. Diode mode on R5100 pin 1 id 0.3 and pin 2 0.5 voltages also correct. I noted something strange on C7094 on pin 1 (P3V42G3H_BOOST) i have 7.2V and pin 2 is ok it's 3.4v.
PPBUS_G3H is 0.2v
PP5V_S5 is 0.8v
PP3V3_S5 is 0.8v
J6100 removed

Any ideas?

Thanks :D
 
2informaticos

2informaticos

Administrator
Staff member
First post diode mode to ground at PPBUS_G3H; be sure F7100 is good.
Post U7100 voltages; pins 1, 2, 3, 9, 12, 13, 14, 15, 17, 19, 20, 27.
 
I

iFix

Member
F7140 is good. PPBUS_G3H diode mode on F7410 pin 2 0.46 and pin 1 is 0.116 when F7410 removed.
U7100:
pin 1 0.26v, pin 2 12.8v, pin 3 3.9v, pin 9 4.2v, pin 12 3.4v, pin 13 3.4v, pin 14 3.4v, pin 15 0.28, pin 17 0.8v, pin 19 5.3v, pin 20 5.3v, pin 27 14.2v
 
2informaticos

2informaticos

Administrator
Staff member
"pin 9 4.2v"
Are you sure about this?
Check R7121/22 and their traces.
Also be sure R7105 has correct value.
 
I

iFix

Member
I replaced R7105, R7121/22 they were bad now it's the correct value on all of them and on Pin 9 now i have 0.8v but i think this u7100 is not good :D
 
I

iFix

Member
I replaced another 2 new and from another board still same. Now pin 9 is 0.7 diode value which is correct and 0v
 
C

CRC2018

Member
Thought i'd chip in here as i've been trolled by these before - if either U7100 or Q7130 has or had a fault they will tend to burn the other one. So if you had a short on U7100 then you need to replace Q7130, if you replaced U7100 without replacing Q7130 you have probably killed the new U7100. Replace both Q7130 and U7100 with new and try. Also check resistance to ground at L7310 - if it's low 1-2ohms you have got a dead processor and basically a trash board so don't waste any time if this is the case!
 
I

iFix

Member
This morning i noticed i got PPBUS_G3H 8.6v and diode mode is 0.135 both side on F7410

pin 1 0v, pin 2 14.6v, pin 3 3.9v, pin 9 0v, pin 12 3.4v, pin 13 3.4v, pin 14 3.4v, pin 15 0.06v, pin 17 8.6v, pin 19 5v, pin 20 5v, pin 27 14.6v

I can replace Q7130 and u7100 no problem but it was showing 0v on PPBUS_G3H maybe it needed cleaning from flux u7100
 
I

iFix

Member
After replacement of Q7130 L7130 pin 1 diode value is 0.130 and 14v which is not good should be 8.6v and i replaced C7125 still the same. On Pin 2 of L7130 it's 8.6v
 
2informaticos

2informaticos

Administrator
Staff member
Why did you change anything, if already got correct PPBUS_G3H???
Now you have burnt Q7130, at least.

Please clarify the actual situation; 14V, or 8.6V at L7130?
 
I

iFix

Member
Update: i replaced back the old Q7130 and i got on Q7130 pin2 8.6v but on q7130 pin 8 i have only 0.5v which comes from U7100. Do i replace another U7100?

Thanks
 
2informaticos

2informaticos

Administrator
Staff member
Why the people like so much to measure MOSFETs Gate?
I will never understand that.

Pin 2 comes from R7120, are you sure to have 8.6V there???
 
I

iFix

Member
Yes i'm sure it was 14v on pin 1. Now when i've put back the original q7130 the voltage on both sides on L7130 is 8.6v and diode is 0.144 both sides
 
2informaticos

2informaticos

Administrator
Staff member
You are free to try again, but I do NOT rtecommend you to waste the time; try to undrrstand the schematic instead.
PPBUS_G3H is correct now, so tell us actual behavior of the board.
 
I

iFix

Member
The board gets a green light and no power. As i said before i reballed the SMC, replaced U7100, u7501 and also i've put new u7701 because it was missing someone took it out before
 
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