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820-3435 Pulsing Rails

MLS

MLS

New member
Hey all :-)

Been struggling on for some time now watching videos etc. relieved to have signed up and apologies for any silly questions..

Have an 820-3435 with Pulsing Rails. Green/Orange light, no fan

PP3V42 3.425-3.427
PPBUS_G3H 8.58-8.65 then every say 3-5 seconds drops to 8.25 for a moment

Some U7100 Measurements
2 - CHGR_DCIN 18-19.6 (using an 18.5v charger which is really 20v)
3 - CHGR_ACIN 5.29-5.35
4 - CHGR_VFRQ 3.1-3.3
9 - CHGR_AMON .052-.062
13 - CHGR_RST_L 3.381-3.387
14 -SMC_BC_ACOK 3.387-3.395

SMC bypass no fan

Multimeter batt should be fine and stable readings on other boards, also with same charger.

Board has a fair bit on moisture exposure, lots of tarnished pads but no actual spills.

Help appreciated!
 
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MLS

MLS

New member
Thanks for the quick replies :-) will check VCore tomorrow as home now.
Where best to measure?
PPVCC_S0_CPU pretty sure was 0v
SMC_CPU_VSENSEOUT @ R5520 also pretty sure was 0v

Many test points are tarnished, nothing eaten through. No spills. The usual " Its ever been wet" from customer, seems about 70% honestly didn't see the splash :-)
High humidity area and near the ocean here.
 
MLS

MLS

New member
Oops.. Late night scribing there. Still higher that usual although much less so. Corrected original post.
9 - CHGR_AMON .052-.062
Will check resistance when back at work, Thanks :-)
 
M

MexicoTV

New member
Hi friend, check out my thread titled 820-0064 need U8080. Your issues sound quite similar to mine. Esp the part about the pulsing PPBUS_G3H. On mine i thought it was U8080 but have found other issues. I was wondering if you could help me too actually and seeing if too the right of your audio codec chip on the DC in/IO board (pin one indicator on the upper left corner) there are some black resistors that measure to ground on both sides. This is so far my closest clue as to what the issue is on mine. Id be happy to take comparison measurements on my board, which although dead have managed to get some life out of it so far.
 
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MLS

MLS

New member
Hey mexicoTV
been working on another board as on a deadline to get sorted for customer.
have checked with another DC board (for a 13?, sits sideways although fine for powering on 11? if that?s the only other option.) and all still pulsing so definitely the main board that?s causing the issue.
are you getting VCore at all? Where are you measuring for vcore?
cheers and good luck!
 
MLS

MLS

New member
Last cal for help on this one! Maybe I'm not posting the right stuff? Noob apologies..

U7100 Voltage list with new good ISL

Changed fluke batteries in case that was giving my random readings and tried with bench power. very similar stull..

[TABLE="cellpadding: 0, cellspacing: 0"]
[TR]
[TD]U7100[/TD]
[TD] [/TD]
[TD] [/TD]
[/TR]
[TR]
[TD]1 - CHGR_AGATE [/TD]
[TD] [/TD]
[TD]0.0005[/TD]
[/TR]
[TR]
[TD]2 - CHGR_DCIN[/TD]
[TD] [/TD]
[TD]19.67[/TD]
[/TR]
[TR]
[TD]3 - CHGR_ACIN[/TD]
[TD] [/TD]
[TD]5.334[/TD]
[/TR]
[TR]
[TD]4 - CHGR_VFRQ[/TD]
[TD] [/TD]
[TD]3.327[/TD]
[/TR]
[TR]
[TD]5 - CHGR_ICOMP[/TD]
[TD] [/TD]
[TD]0.214[/TD]
[/TR]
[TR]
[TD]6 - CHGR_CELL[/TD]
[TD] [/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]7 - CHGR_VCOMP[/TD]
[TD] [/TD]
[TD]0.722[/TD]
[/TR]
[TR]
[TD]8 - CHGR_VNEG[/TD]
[TD] [/TD]
[TD]0.255[/TD]
[/TR]
[TR]
[TD]9 - CHGR_AMON[/TD]
[TD] [/TD]
[TD]3.966[/TD]
[/TR]
[TR]
[TD]10 - SMBUS_SMC_5_G3_SDA[/TD]
[TD] [/TD]
[TD]3.425-3.427[/TD]
[/TR]
[TR]
[TD]11 SMBUS_SMC_5_G3_SCL[/TD]
[TD] [/TD]
[TD]3.425-3.427[/TD]
[/TR]
[TR]
[TD]12 - PP3V42_G3H [/TD]
[TD] [/TD]
[TD]3.426[/TD]
[/TR]
[TR]
[TD]13 - CHGR_RST_L[/TD]
[TD] [/TD]
[TD]3.390[/TD]
[/TR]
[TR]
[TD]14 -SMC_BC_ACOK[/TD]
[TD] [/TD]
[TD]3.357[/TD]
[/TR]
[TR]
[TD]15 - CHGR_BMON[/TD]
[TD] [/TD]
[TD]0.063[/TD]
[/TR]
[TR]
[TD]16 - CHGR_BGATE[/TD]
[TD] [/TD]
[TD]Random .4 to .8[/TD]
[/TR]
[TR]
[TD]17 - CHGR_CSO_N [/TD]
[TD] [/TD]
[TD]3.8 to 4.6 pulsing[/TD]
[/TR]
[TR]
[TD]18 - CHGR_CSO_P[/TD]
[TD] [/TD]
[TD]3.9-4.1 Pulsing[/TD]
[/TR]
[TR]
[TD]19 - PP5V1_CHGR_VDD [/TD]
[TD] [/TD]
[TD]5.010[/TD]
[/TR]
[TR]
[TD]20 - PP5V1_CHGR_VDD[/TD]
[TD] [/TD]
[TD]5.010[/TD]
[/TR]
[TR]
[TD]21 - CHGR_LGATE[/TD]
[TD] [/TD]
[TD]0.033[/TD]
[/TR]
[TR]
[TD]22 - PGND[/TD]
[TD] [/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]23 - CHGR_PHASE[/TD]
[TD] [/TD]
[TD]4.0-4.1 pulsing[/TD]
[/TR]
[TR]
[TD]24 - CHGR_UGATE [/TD]
[TD] [/TD]
[TD]4.2-4.8 pulsing[/TD]
[/TR]
[TR]
[TD]25 - CHGR_BOOT[/TD]
[TD] [/TD]
[TD]6.4-6.45 pulse[/TD]
[/TR]
[TR]
[TD]26 - CHGR_SGATE [/TD]
[TD] [/TD]
[TD]19.49[/TD]
[/TR]
[TR]
[TD]27 - CHGR_CSI_N[/TD]
[TD] [/TD]
[TD]19.77[/TD]
[/TR]
[TR]
[TD]28 - CHGR_CSI_P[/TD]
[TD] [/TD]
[TD]19.51[/TD]
[/TR]
[/TABLE]
 
MLS

MLS

New member
Thanks for the reply 2informaticos

I can't find those resistor numbers on the 820-3435 schematic?

Will check traces around U7100.
 
MLS

MLS

New member
Checked CHGR_AMON again and reading .030 Must have muted up that reading? Sorry.

Noticed when using Bench power its only pulling .008 amps, orange light on.
 
2informaticos

2informaticos

Administrator
Staff member
Does the board start on battery only?

Post exact value (ohm scale) for R7180/81 and R7185/86.

Mea culpa for above; read R712x instead of R702x...
 
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