[SOLVED] 820-3436 - Green light for half a second, then full fan.

[gcain]

Make that an 820-3437-B rather.
(I haven't even started drinking at my desk yet... :/ )


History is a bit unclear, but was definitely water damaged.

Replaced the DC board with a spare one. Now it gets a green light for a split second and then it goes out and the fans turn on full. It doesn't speed up, it just goes full speed.

Not getting P3PVS0_EN.

 

[dukefawks]

Nothing to go on and P3PVS0_EN does not exist.

 

[gcain]

I'm taking measurements! Have them up in a moment.

And that was a typo; P3V3S0_EN.

 

[gcain]

PP5V_S0 = 5v12
PP3v3_S0 = 40mV @ R5361
P3V3S0_EN = 16mV @ R8070


U8180::1 = 3.34
U8180::2 = 3.34
U8180::3 = 0
U8180::4 = 0
U8180::5 = 3.34

 

[gcain]

I am trying to find where P3V3S0_EN is not coming from.

D8184::1 = 16mV
D8184::2 = 16mV

R8184 = 16mV.

Pin 4 of U8180 is 0v so nothing after that is going to give me anything....

 

[dukefawks]

P3V3S0_EN comes from the same place as P5VS0_EN (R8186/87). So check the traces and resistors in P3V3S0_EN lines.

 

[gcain]

What should I expect to see from U8180:in 4 (PM_SLP_S3_BUF_L) ?

I'm getting 16.5mV, which makes wonder how it can ever be turned into 5v_en and 3v_en, I can't see another power line involved anywhere.

 

[dukefawks]

In post #4 you say you have PP5V_S0, this suggests P5VS0_EN is there, check again.
Also if pin 1,2 and 5 of U8180 have voltage then pin 4 should be high too, check again.
Actually if the fan spins usually all power is ok with possibly the exception of CPU Vcore. Check ALL_SYS_PWRGD.
Also I'm looking at the 3435 diagram as 820-3436 does not exist.

 

[gcain]

(The board is 820-3437, I corrected myself in the first post.)


There is no PP5V_S0 at this stage.

Pin 4 is definitely low on U8180, and pins 1,2 & 5 are definitely at 3.345v.

ALL_SYS_PWRGD = 0;

What would cause the green light to go out after a little time?
Sometimes it's green for a few seconds, sometimes a split second. PP3V42_G3H is present everywhere i check.

 

[gcain]

But I do have PP5V_S0_FET_R....

Is that even possible?


Edit.

At C8080, but nothing at R8187.

 

[gcain]

PP5V_S0 is back @ C7320

The bloody thing must be intermittent. :/


Edit:
Gone in the bin.

 

[gcain]

Had some time so took a second look; a pin on the flex cable from the DCBoard to the MLB was burnt out.
Groan.

Swapped that over and it behaves as expected.

Learnt to be more thorough with this one. I tried known good DC Boards but used the same flex cable each time....

Mark this as solved/closed please.