820-3437 liquid on u7501 and u1900

[ielectron]

i replaced u7501 (new chip)and u1900 (from donor board), there is green light, i can do SMC reset
-the board takes 0.380A when i connect the charger, than that goes back to 0.200A and stays there

i see no water else where, only on those 2 chips, and some resistors around, i replaced all of them, no here is the measurement for

u7501

1	0
2	0
3	1.245
4	0
5	0
6	1.998
7	0
8	0
9	0
10	1.998
11	0
12	3.4
13	1.998
14	5
15	1.96
16	1.01
17	3.3
18	3.3
19	1.99
20	3.3
21	3.4
22	3.3
23	8.57
24	4.01
25	3.3
26	8.33
27	1.1
28	0
29	5
30	4.8
31	0
32	0

u1900

1	0.135
2	3.27
3	0
4	0.004
5	3.28
6	1.19
7	1.19
8	0.34
9	0
10	0
11	0
12	0.125
13	3.4
14	3.29
15	0
16	0

 

[ielectron]

fan is not spinning

 

[ielectron]

in the meantime i found another good board, the measurement for this

u7501
1	5.5
2	5.1
3	1.25
4	3.33
5	0
6	1.996
7	0
8	0
9	0
10	1.996
11	0
12	3.4
13	1.996
14	5
15	1.97
16	1
17	3.3
18	3.3
19	1.996
20	3.3
21	3.4
22	3.3
23	8.59
24	3.59
25	3.34
26	8.44
27	0.38
28	0
29	5
30	0.38
31	10.17
32	5.1

u1900
1	3.3
2	3.3
3	1.2
4	1.09
5	3.33
6	1.19
7	0
8	0.56
9	0
10	0
11	0
12	0.391
13	3.4
14	3.3
15	1.66
16	0

 

[ielectron]

so my u1900 is not giving 3.3V on the leg 1, so the crystals are not working? the leg 1 was corroded, i removed it, pad cleaned, chip replaced, but still no 3.3

 

[ielectron]

i replaced u1900 and the 25 mhz chrystal again, same

 

[2informaticos]

Did you check resistance to grounat pin 1/U1900?
If OK, then check for 3V at pins 2 & 13 of U1900.

25MHz will not appear untill board starts.
You must get first 32KHz at pin 12.

 

[ielectron]

i dont have 32khz too

1/U1900 is 1ohm, that pin goes the the CPU, doesn it mean cpu is shorted?

 

[JohnB8812]

If you have a short on pin 1, you need to remove U1900 first to see if it goes away. If not, the cap next to it can cause the short. If not that, there are 4 other big caps on the board for RTC. If you remove all 5 caps and U1900 and it’s still 1 ohm, then yes dead CPU

 

[ielectron]

yep, cpu is shorted