820-2936-B Rails pulse (except PP3V42 and PPBUS)

2informaticos

Administrator
Staff member
If board starts with battery + charger, check watage charger on system report.

"SMC_ADAPTER_EN 0V
PM_BATLOW_L 0V"
Usually sign of incorrect charger...
I doubt to be SMC issue, as the board works on battery.
 

djdblaster

New member
When Q7221 was removed, I didn't have any voltage on pin 5 P3V3S5_EN_L.

Q7221 is back now. Laptop doesn't start with battery and charger plugged in. Battery voltage without charger is 11.5V.

When I use it on DCPS with original charger head, laptop draws 20mA.
 
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2informaticos

Administrator
Staff member
"When Q7221 was removed, I didn't have any voltage on pin 5 P3V3S5_EN_L."
Why would you want to have voltage on an active low enable signal?

"PM_BATLOW_L pulses
SMC_ADAPTER_EN pulses"
Do you have steady 0V now???
 

djdblaster

New member
"Why would you want to have voltage on an active low enable signal?"
It was present on pin 2 Q7221 P5VS3_EN_L, but only because it's connected to PP3V42, right?

Yes, I have 0V now.
 

2informaticos

Administrator
Staff member
P5VS3_EN_L should be low (0V) to enable 5V_S3 power rail.
That's the reason I told you to remove Q7221.
In this way, both 3V and 5V sections of U7200 are always enabled.
 

2informaticos

Administrator
Staff member
"Remove Q7221 and check again all the voltages
-----------------
No 5V coming from U7200 with Q7221 removed."
You didn't mention that untill now...

So post now U7200 voltage, pins 16, 13, 3, 8, 17, 1.
Check R/C7260, R7267/68 and Q7260/61.

Q7221 removed, of course...
 

djdblaster

New member
Q7221 now removed & pad voltages:
pin 1 - GND
pin 2 - 3.45V
pin 3 - 0.74V
pin 4 - GND
pin 5 - 0V
pin 6 - 0.9V

U7200 voltages:
pin 16 - 12.59V
pin 13 - 3.42V
pin 3 - 2V
pin 8 - 3.3V
pin 17 - 5V
pin 1 - 0.9V

R7260 pin 1 (0.568) pin 2 (0.568)
C7260 pin 1 (0.568) pin 2 (0.118)
R7267 pin 1 (0.118) pin 2 (0.677)
R7268 pin 1 (0.677) pin 2 (GND)
Q7260 pins 123 (0.118) pin 4 (0.647) pin 5 (0.423)
Q7261 pins 123 (GND) pin 4 (0.613) pin 5 (0.118)
 

2informaticos

Administrator
Staff member
"Check R/C7260, R7267/68 and Q7260/61."
I was refering to their integrity and correct value...

If all resistors and traces are OK around U7200, change the chip.
Post resistance to ground at L7260; diode mode, both ways (red and black to ground).
Maybe Q7260/61 need to be changed too.
 

2informaticos

Administrator
Staff member
You could have a problem outside of that power supply.
But must check and change all possible there first.

Cannot get any pulse at L7260?
Check when trigger SMC_ONOFF_L...
 
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2informaticos

Administrator
Staff member
Recheck all traces and resistors.
L7260 should have 5V with provided values (when Q7221 removed).
Change U7200 and Q7260/61 too.
 

djdblaster

New member
Replaced U7200 and Q7221. PP5V_S3 is present now. I seem to have S3 rails now, but not S0.

PP5V_S0 - 0.033 resistance

Am I safe if I inject more than 1V into the line since it feeds some 1V lines?
 
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2informaticos

Administrator
Staff member
0.033 in diode mode is aprox 60 ohms.
Usually you cannot heat anything with 5V there.
But you can try, maybe some IC enter in avalanche process and overheats...

First remove U5850 and test again.
I found bad keyboard backlight circuit few times.

PM_SLP_S3_L goes high, or pulses at least?
 

djdblaster

New member
Okay, so I've removed and replaced U7100 and U7600 and PP5V_S0 is back to normal 0.360.

I'm drawing 44mA from DCPS. PP5V_S0 not present though.

I have lower resistance in Ohms on CPU compared to known good (10 vs 17 Ohms).

PM_SLP_S3_L - 2.26V
PM_SLP_S3_L - 0.038
 
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2informaticos

Administrator
Staff member
"10 vs 17 Ohms"
Could be the difference between processor type; i.e. i5 vs i3 (or i7 vs i5).

"PM_SLP_S3_L - 2.26V
PM_SLP_S3_L - 0.038"

If PM_SLP_S3_L goes high, PP5V_S0 should come on too.
If not, change Q7860.

2.26V is a bit on the bottom edge of high level; should be closer to 3V (usually 3.3V).
Check PM_SLP_S3_L on both pins of R7978.
 
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