820-2532-A Powers on but....

[myiannakou]

Hi MacBook 15" 2008 board 820-2532-A
It would not power on but I repaired it so it now powers on but Beeps once every five secconds. This goes on forever.
According to Apple's support site this indicates a RAM issue or RAM not being detected by the Mac.
Have tried swapping out the RAM but no luck.

The initial repair I did was replacing U7700 and the components surrounding it and rebuilt alot of the tracks around that area. I think this area may have had liquid damage or the charger used was a knock off one.

Any help appreciated. Thanks

 

[2informaticos]

Do you get correct L7700/80 voltages?
Also check L7330 and L7100.

 

[myiannakou]

0v on L7700
0.5v on L7780
1.49v L7300
.99v L7100

 

[2informaticos]

So you still have problems on U7700 area.
Post its voltages.

 

[myiannakou]

P1V0FW_VFB = 0.3v
PP3V3_S0 = 3.29v
PP3V3_S3 = 3.29v
P1V0FW_VFB = 0.49v
P1V8S0_LX = 0v
P1V8S0_EN = 1.50v
P1V8S0_FVB = 0v

 

[2informaticos]

Check R/C7883.

 

[myiannakou]

They are both good. No short on cap and resistance on R7883 = 9.93K ohms (measured in circuit)
Is P1V8S0_EN too low at 1.5v ?

 

[2informaticos]

It should be 3V, as it comes from PM_SLP_S2_L_R.
Remove C7883 and check again the signal.
If still low, change U7700.