820-2877-b with fluctuations on ppbus_g3h

Chuck60

Member
Hi I got this board a while back but hadn?t bothered to look at it. I?m just trying to learn these repairs and I?m sorry the majority of the boards are old. Anyway I replaced d7005 one of the diodes was no good it had continuity in diode mode in both direction while the other side did not pin 3had 0 continuity to r7005 so I ran a wire. I u7200 had a short to ground on pin 16. Test pin 16 without u7200 .469v Replaced u7200. No I have a green light on the charger and ppbus_g3h is turning on every 30 seconds almost as if it?s sensing a current draw and shouting down.

U7000
chgr_dcin = 16.59v
chgr_acin = 4v
smc_bc_acok = 3.3
pp5v1_chgr_vddp =4.9v
chgr_rst_l =3.41v

u7200
5v3v3s5_reg3=
3v3s5_entrip=
 

2informaticos

Administrator
Staff member
3V3_S5 tries to appear?
Post basic voltages for U7200, pins 16, 13, 3, 8, 17.
Post real voltage on pins 1 & 6 too.
 

Chuck60

Member
Hi yes I just rotated u7200 and now I have good
ppbus_g3h = 12.56v
pp5v_s5 = 5v
pp3v3_s5 =3.3v
tried power on pads and nothing the pad also has 3.42v
no s3 or s0 rails
 

2informaticos

Administrator
Staff member
C7755 correct voltage present?
Post resistance to ground (ohm scale) at L6995; should be higher than 30K.

Check all RTC signals.
 

Chuck60

Member
Sm_intruder_L =3.4v
pm_rsmrst_L = 3.4v
I?m having a hard time finding a point to check drop pulse at pm_pwrbtn_L one is un smc and the other is under cpu. I don?t see a test point or resistor to test from in between the two points.
 

Chuck60

Member
Also c2620 is not present and looks like it?s knocked off.
pp3v3r1v8_so_mcp_ifp_vdd on pin 1 pin 2 is gnd
 

2informaticos

Administrator
Staff member
"smc_onoff_L it doesn?t drop or even move"
Do you mean is always 3V, or just 0V?

C2620 shouldn't be a reason for not starting, but I recommend you to solder it anyway.
Old platform, no way to measure PM_PWRBTN_L; sorry, didn't check that on schematic.
 

2informaticos

Administrator
Staff member
These old machines get failing power button.
Check first if R5710 is good.

Use R5014/15 and check for pulse at PM_SLP_S4_L.
Be aware, MCP could be bad, after so many years.
You can try heating it...
 

Chuck60

Member
I just found the issue :) it?s the q7860 that gave pm_slp_s4_L
so I wasn?t getting signal. It chimes I have video and I pop in a install dvd all is good so far. Thank you for your time :)
 
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