820-2850 - ppbus_g3h 0.195v

[ClarkDV]

820-2850 - Liquid damage

Green LED is ON, no fan.

PPDCIN_G3H - 17.05v
PPBUS_G3H - 0.195v
PP3V42_G3H - 3.398v
PP5V_S5 - 0.00v
PP3V3_S5 - 0.00v


Via to the left of R7052 is blown

According to the schematic, R7051 is connected to U7000 but R7052, with the blown via, is not.


Should I worry about the blown via connected to R7052?

Thanks

 

[larossmann]

put black end of multimeter on pin 1 of c7050, put red end of multimeter on pin 2 of c7050, in resistance mode. what do you get?

 

[ClarkDV]

C7050 - 6.74M Ohms

 

[larossmann]

before i get to a real computer to provide proper answer, you tell me why that is very very wrong add resistance of r7050, r7051, and r7052.. do they add up to 2.203 ohms, or 6,740,000 ohms? go hunt for your break in the line!

 

[ClarkDV]

So R7052 should be connected to R7050 thru that via?

 

[Crizz]

YES!
R7051, R752 and R7050 have to be physically connected!
These are responsible for current sense ....
According to your description your machine thinks it is on fire and shuts PPBUS off

 

[larossmann]

Now go run a wire!

 

[ClarkDV]

Thanks, like I said, my schematic does NOT show R7502 connected to U7000, that's why I wanted to ask and double check what it should be connected to. I'm not stupid, just careful.

 

[ClarkDV]

R7052 came off the board when I was attempting to connect the jumper wire to Pin 2. Because it's a 0 ohm resistor, is it crazy of me to consider just connecting the jumper directly to the Pin 1 pad, thereby replacing the 0 ohm resistor with a 0 ohm jumper wire?

 

[ClarkDV]

OK, so I jumped R7050 Pin 2/4 to R7052 Pin 1 solder pad (R7052 is not on the board anymore, is that OK??)

NOW have 12.5v on PPBUS_G3H and PP5V_S5 and PP3V3_S5 are now present too.


But still no fan, do still have Green LED and these voltages:

PPDCIN_G3H - 17.03v
PPBUS_G3H - 12.56v
PP3V42_G3H - 3.398v
PP5V_S5 - 4.99v
PP3V3_S5 - 3.32v


PP5V_S0 - 0.00v
PP3V3_S0 - 0.00v

PPVCORE_S0_CPU - 0.00v
PPVCORE_S0_MCP - Not Present on Board View File
PP1V05_S0 - 0.00v

 

[Crizz]

Check for PP1V05_S5

 

[ClarkDV]

PP1V05_S5 - 0.00v

It looks like PP3V3_S5 makes PP1V05_S5 at U7740.

However, U7740 is a No Stuff on this logic board...

Thoughts?

 

[ClarkDV]

Hello? Louis, Duke?

 

[aprendiz]

PP1V05_S5 is not needed....
PM_SLP_S4_L is present?????
By the way, use a 0 ohm resistor for R7052 and the wire just for rebuild the trace....

 

[dukefawks]

Check PP5V_S3 for short first and then see if it pulses when power is applied. It may only pulse once very shortly after connecting power so check carefully.

 

[ClarkDV]

PP5V_S3 at CD230 Pin 1 reads .401V in Diode Mode
PP5V_S3 at C7300 Pin 1 reads .401V in Diode Mode

So it looks like PP5V_S3 is not shorted to Ground. (unless .401v is WAY off of what it should be?)

When checking voltage at C7300 Pin 1 with NO power applied it reads 0.000v.
When I apply power it goes to 0.002v.

 

[dukefawks]

I asked to check for short pulse(s) right after applying power. It may only pulse once and hard to catch on a multimeter.
Did you check power to RTC? R1800-1803?

 

[ClarkDV]

Ah, I wondered if it might be too fast to see on a DMM, you gotta be explicit with your instructions!

Will check all that and get back to you soon.

Thanks

 

[ClarkDV]

C7300 Pin 1 (O’scope test) - maybe a 20mV pulse at 100mV/2s setting

RTC Power C2810 Pin 1 - 0.366v
RTC power C2811 Pin 1 - 0.401v

RTC - 32.89KHz signal present

R1800-R1803 all have 3.398v on Pin 1 and between 3.1 and 3.3v on Pin 2

 

[dukefawks]

Was this a liquid damage?