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820-00165 - does not turn on with battery connected

Palhano

Palhano

Member
arrived not working. It has no oxidation, it just had a short on C7434. I replaced it and the board turned back on. But if you connect the battery, the board turns on and off in a few seconds, sometimes it doesn't even turn on.

I already tested with another battery, with another DC card. Same thing!
I have the 3V42_G3H with the battery connected
I already checked the C7105 and the traces of the R/D7105
R7121/22 and R7151/52 are OK.
 
Palhano

Palhano

Member
situation has changed!
The board now turns on and a few seconds later stops, even without the battery.

When you turn on the PPBus it is staying at 8.2, when it turns off, it goes to 8.6v.

With the battery connected, the board does not turn on and the PPBus is 8.6v
 
2informaticos

2informaticos

Administrator
Staff member
Make it work with charger alone first.

Try starting in SMC bypass mode.
Check resistance between pins 17/18 and 27/28 of U7100.
 
Palhano

Palhano

Member
It only gets worse! LOL

The board has stopped turning on at all. PPBus 4v. SMC bypass mode does not work.
17/18 - 3
27/28 - 20

Rebbaling SMC?

Board turning into a snowball of problems!
 
Palhano

Palhano

Member
R7113 perfect. Pin 6 - 0v

PPBus is now floating, 8.4v, 7v, in some moments it goes to 0 and goes up again!
 
Palhano

Palhano

Member
Stable C7140 at 8.6v.

replace the F7140 and turned on! \o/ I'll continue with the tests!

thank you very much!
 
2informaticos

2informaticos

Administrator
Staff member
"it just had a short on C7434"
That damaged F7140.
Internal fracture of the fuse is not easy to detect with nultimeter; ohm scale, or diode mode.
It fails under high current...
 
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