A1534 820-00045-A no power

[hgoncalves]

Hi,
I have an A1534 820-00045-A that has no power.
It takes 5.16V from ampmeter and 0A.
I have 5.16V on F4700 and 0V on 3V3R3V0_AON.

Diode Readings:

3V3R3V0_AON = 0.331
E85_CC1 = 0.555
E85_CC2 = 0.555

I supose that it can be related with U4700. Am I right?
Can you help?

 

[2informaticos]

U4700/80 are the first suspects on this board.
Can be also faulty U7100.

 

[hgoncalves]

Hi,
I alreay replaced U4700/80 and U7100, but with the same result.
What more can i check?

 

[2informaticos]

Check basic voltage for U7100; P_IN, ACIN, VDDA/P.

 

[hgoncalves]

U7100 Voltages:
PPVIN_G3H_P3V3G3H = 0.027V
CHGR_ACIN = 1.298V
CHGR_LDO_VDDA = 0.155V
CHGR_LDO_VDDP = 0.060V

 

[2informaticos]

Didn't find corresponding line to P_IN?
What about R7120?

 

[hgoncalves]

Sorry, I've missed that.

PPDCIN_G3H_CHGR = 5.177V
R7120 seams to be OK. I get 5.177V on the 4 pads

 

[2informaticos]

At least one of R7101/04 is burnt.
And possibly one of C7100/01 bad too.

 

[hgoncalves]

Hi,

R7101 = 0 ohm
R7104 = 4.6 ohm

C7100/01 seams to be ok, but I've removed both. However, I still have the same behavier.
CHGR_LDO_P5V0 (on R7104) = -0.141V
Shall I replace R7101/04 ?

 

[2informaticos]

I've got confused between voltage and diode mode at VDDA/P pins, sorry.
However, you should change U7100 again.

 

[hgoncalves]

I don't have any more of those. Can I take from a 820-00244 board? Do you know any good suplier for them?

 

[2informaticos]

It should work from 00244 donor board.

 

[hgoncalves]

I've replaced U7100 again (twice), but same thing. However I get some strange readings (I think):
I've used 2 multimeters and in CHGR_LDO_VDDA I get negative voltages (-0.221V), and on CHGR_LDO_P5V0 I get -0.080V. Does this make any sense to you?

 

[hgoncalves]

Do you think that I should give up on it?

 

[2informaticos]

If U7100 is good for sure and properly soldered, then must have a problem with surrounding components.
Check diode mode to ground at L7095 and F7140.