3.3V is not shorted. I have had cases when this 3.3 was missing it was one of the caps under the wifi ic but this is one is strange. Pin 13 enable does not have any voltage (0V). Resistance to ground on this pin is in 100K ohms.
Appreciate your time.
To add enable voltage on SB PMIC (pin 29) is also not present
There is another TLV62090 for generating 1.95V. The PG signal (pin 4) from this chip is the enable signal for the SB PMIC.
I would check if 1.95V are present at the output caps and coil.
There are 2 such chips at the back. The one near F7502 has 2V output and the one near USB circuit has 0V output. The exact one you shared, i couldn’t find it on my board.
Okay found it on the same side of the board near disc driver connector. Output is 0V
The input 5.1V are present at the chip?
What is the resistance to ground at the light blue marked caps and coil?
Yes 5.1V input is present at the chip (at pin 3, 10,11,12). Resistance to ground at light blue marked caps and coil is more than 100K Ohms and climbing.
What keeps bothering me is the 3219A chip having 0V standby at pin 16. I also replaced this chip with the known working one but still same behaviour. The resitance to ground is 22 ohms. On a working edm-010 board i always get 5V standby.
Even with the chip off the board this test point has 22 ohms resistance to ground.
Btw on the original board, voltage regulator that generates 5V was from a different manufacturer. Here is the photo of the original part which turned out to be bad.
I replaced it with known good 3219A. I hope they are interchangeable ?
This chip can be a TPS53219 or a MM3736. They are interchangeable.
The 0V at pin 16 (PG signal) is a problem. Because this PG signal enables the TLV62090 for 1.95V at its pin 1 (EN).
By any chance, is there any liquid metall left over around the 3219A? This spot would be a good candidate:
If no liquid metall is shorting the line, I would pull both chips and check if this line goes back to a good 10k ohm reading.
Check this 10k ohm resistor on pin13 EN line for the TLV62090. The SB wont call to turn on if missing 1.9v from this output here
Resistance of this resistor in the circuit is 100k ohms. When i lift it off the circuit, it measures 10k ohms.
Is your F7003 good? pin13 5v EN for IC7002/tlv62090 should come straight from 5v standby, and it also goes into pin16 on 3219A as well
Something is not matching.
22 Ohm at pin 16 of the 3219A and 100k Ohm at pin 13 at the TLV62090. This is one line and should have the same readings.
Sorry, I was not clear. 100k ohms was the resistance of the resistor (highlighted by jkyoho) in the circuit which should measure 10k ohms. It led me to doubt TLV62090 chip having internal damage. You were correct pulling TLV62090 chip resulted in a good 10k ohms resistance at pin 16 (PGOOD) of 3219A.
I just installed a known good tlv62090 and now I have 5V at pin 16 of 3219A and all standby voltages are back. Thanks a lot for pointing me to the right direction.
I’m joining in because I have a similar problem.
UART directed me to area F7002 - 5V Short
The fuse was open. I removed it, but before replacing it, I detected a short on the capacitors in the photo (upper part)
On one side of F7002 and on the other side.
I tried injecting 1.5V - 1A fuse side, but I didn’t find any spots with the thermal camera.
Any ideas?
mark where you find short please
The left cap on the second image looks damaged on the lower corner. But I would expect to heat up if shorted to ground.
