820-0165 Fan spin about 1 sec, then off.

[rsiesta]

After fan stops pulling about 24ma from the charger.

Going down the power rails I have everything till PP5V_S4RS3, on U7501 it is 5V
while fan spins, then down to zero when fan stops on pin 2. It looks like something
stops telling it to turn on. Any suggestions?

 

[JohnB8812]

Sounds like possible power cycling. Does CPU VCore come high too when the fan spins?

 

[2informaticos]

All the secondary coils get voltage, or pulse at least?
ALL_SYS_PWRGD pulsing too?

 

[rsiesta]

ALL_SYS_PWRGD goes to 3.3v then zero on pin 1 of U1950
PPVCC_S0_CPU on R7320 pin 2 peaks at 1.8v then zero
Both come up with fan spin, then go to zero when fan shuts off.

Just to make sure I am saying this correct, the fan spin and the voltages come
up when I connect charger, then about 1 second later the fan stops and
the 2 above voltages go to zero. At this point the voltages on the rail page above
PP5V_S4RS3 are all correct and present. Nothing changes that I have
found once the fan spin stops. If I disconnect/Reconnect the charger I get the 1 sec
fan spin then back to steady state until I disconnect the charger again. There
is no cycling or any of the voltages not present going above zero again.

 

[2informaticos]

Pins 7 & 3 from U1950 pulsing too?

 

[JohnB8812]

Ok so power cycling ang history liquid damage etc?

 

[rsiesta]

Both 7 and 3 act just like 1, voltage when charger connected for brief second, then nothing.

 

[rsiesta]

No history, I wish I had stuff brought in for repair, but I am learning on
boards listed as for parts or repair on ebay so I am probably buying donor boards .
I could find no liquids or corrosion on the board and no sign anyone had tried repairing it.

 

[2informaticos]

What you get on pin 2 of U1950?
If 1 & 2 pulse, then 7 must pulse too.
Be sure pin 8 receives 3V...

 

[rsiesta]

U1950

When first plug in charger (These are just watching display for highest value, before went to second values)
(Did not use max/min function)


1 3.4v
2 3.4v
3 3.4v
4 0.040v
5 3.4v
6 3.4v
7 3.4v
8 3.4v


After charger plugged in 5 sec and fan spin stopped, these stay
same till you remove and reconnect charger.

1 0.003v
2 0.059v
3 0.002v
4 0.002v
5 0.007v
6 0.002v
7 0.007v
8 3.44v

 

[2informaticos]

Is now time to check all SPI resistors and traces.
Also check U6100/01 for corrosion.

 

[rsiesta]

Checked all 22 of the resistors, they look good, checked all the pins on 6100/01
only the ones that should be ground were to ground. No visible corrosion.
Just have the traces to check left to do.

I take it this is failing when trying to load the bios?