820-4924 Beep RAM

[iClub]

I did reballing the 4 memories, in the tests it worked normally, but after almost a day the mac turned off and presented a memory beep.
. Tell me it's not CPU.


Voltage: L7430 0V.

 

[2informaticos]

"Voltage: L7430 0V"
Solve this first.
Short, or low value to ground at L7430?

 

[iClub]

Low value.
133mV diode scale.

 

[2informaticos]

Seems that you do not understand the difference between diode mode and voltage range of multimeter.
0.133 on diode mode is correct value.

Post U7400 voltages; pins 12, 16, 17, 6.

 

[iClub]

12 PP5V_S3 0v
16 DDRREG_EN 0v
17 MEMVTT_PWR_EN 0.15v
6 DDRREG_1V8_VREF 0v

 

[iClub]

Replaced the u7400 and q7430, checked the R7425/C are ok, I imagine CPU is the defect ?

 

[2informaticos]

"12 PP5V_S3 0v"
Do you really get beep error without voltage at L7520???

 

[iClub]

It was measuring with the board out of the housing, it was giving 0V in the L7430, now I measured in the coil is giving 1.2V.
I imagine it is CPU, because I made reball Memories ?

 

[2informaticos]

Coukd be CPU issue, or bad solders at RAM chips.