Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

[marce002]

Please help me with this!!

Macbook 820 3209 (A1466), replaced TPS51980 3.3v and 5v power supply, and now seems to be turning on and chime. No video. with resistor R7811 removed.
All coils look correct vol, and also resistance to ground .
Seems values similar to working board (resistance and diode mode to ground at each coil)

The problem noted is in RESISTOR R7811 0 ohm , that pin1=3.3 but pin2=1.73v so disconnected to avoid any further damage... problem is cant find any short to ground in areas behind that pin 2 of resistor... looks normal, how can I diagnose if the problem is USB HUB, CARDREADER, LCD or the rest of the items hanging from it look:

[mon2]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

With the 0 ohm resistor removed, what is the resistance to ground on 2 ?

Usually the caps are suspects that cause such events so check around for bulk tantalum caps.

Also check for possible liquid damaged parts that can cause corrosion and again excessive loading of the power rail.

Post your updates.

[marce002]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

thanks ... yes pin2 it is a bit low in ohms 44.7ohm ..
in diode mode=0.067V...

i will try to find any shorted cap (should I inject 3.3v in pin 2? or measure shorted caps to ground?)

[mon2]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

If you have very sensitive meter that can measure in milliohms then you may be able to isolate the cap by individual cap readings. There is an open source design here in this forum that is suitable and should be affordable.

Otherwise, please inspect carefully for possible liquid damage first.

The reading does sound low for this rail.

If you are sure the parts on this rail look ok, then consider to inject 1volt onto pin 2 and note the current draw.

We typically use a q-tip and wet it with alcohol and then touch each local tantalum cap. Then inject this voltage and check for any steaming up of a cap. This process has worked for us at least 3 times and the bad cap was found, removed and the rail returned to a much higher resistance. The logic board worked for us after this exercise.

Please proceed carefully and do not use higher than 3 volts on this rail.

Please post your results.

[marce002]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

ok I m doing so, im at 3vol drawing 0.290A 290mah ... it will be extremly hard because nothing gets warm at all, no sign o any cap heating, it was only drawing 0.064mah at 1.5v injected on pin 2 r7811... that is why increased at 3vol but nothing seems to be the culprit... maybe an IC from the 4 or 5 in the region?....keep looking anyway (i have an identical working board just in case to measure)
u2752 just a bit warm respect to the rest.

[mon2]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

With power off and same resistor and battery removed, what is the resistance to ground on the working logic board for the same resistor, pin #2?

[marce002]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

new working board idetical , resitor removed pin2= a lot higher = 127kohm
and diode mode 0.403v

[mon2]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

Had to tame the jungle in the backyard or face the never ending complaints from the wife....let me load up the schematic to see if we can find something else...

Ok...please read the suggestions below and review each in the order you prefer - perhaps the removal of the LCD panel is the easiest to try first. You are correct on the many downstream devices that depend on this rail but one of these has to be the guilty party.

What was the history of this unit? Liquid damage? I think that you will have to investigate each leg to find the root cause of this issue.

1) remove 10k (0201) @ R2612 and then check the resistance to ground again on pin 2 of R7811. If no change in the resistance, place R2612 back and continue..

2) remove R2616 and R2617 (both are 10k, 0201 resistors) and then check the resistance to ground again on pin 2 of R7811. If no change in the resistance, place these parts back and continue..

3) Check for the presence of R2601, R2602, R2603, R2604 and if they are stuffed, confirm their values are correct @ 10k each. I think that these are USB hub strapping 'jumpers' but currently too lazy to bring up the datasheet from Microchip (USB2513B) to confirm. For this strapping, most likely they will not all be present - that is 2 of these parts are to define '1' logic level while the other 2 are for '0' parking of these lines.

4) U2660 appears to be a USB MUX device from Pericom / Diodes Inc. If you are comfortable with the process, consider to carefully remove (desolder) from the logic board. Once off the board, confirm the pcb pads are clean and not shorting. Then check for the resistance again on pin 2 of R7811. If no change in the resistance, place this part back and continue..

5) Same as (4) process for U2752

6) Same as (4) process for U2800

7) U3500 could be interesting as it accepts the 3v3_S3 to power itself and also powers the docked SD card. What if the SD card use damaged the internal power switch which in turn is impacting the same voltage rail? Consider to remove U3500 (GL822) from the logic board and see if this improves the resistance on pin 2 of R7811.

8) Remove your airport card if you have not done so already and check the resistance again...

9) Remove the LCD cable on J9000 and check the resistance again...

10) USB muxes are interesting since they interface to the outside world for the USB lines. To date, have not seen the schematics for the LIO board but assuming that they feature some level of ESD protection on the USB interface lines. If some nasty transient came through the LIO board -> reaches the USB MUX -> mux can be damaged and then cause the same voltage rail to be loaded down more than normal.

Painful process but cannot think of a better solution at this time.

Please post your updates.

[marce002]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

I did not read your last edited post before i have done this:

removed u2600 USB2513B !! and now the resistance is (0.222Mohm), but is a big chip related to USB HUB & MUX... and i was seeing usb activity in one port when i tested chime, so did not think was bad..... but short is gone..... is it safe to test/power on without this chip? to check for video?


Sorry history of this macbook is that I have bought it non working cheap, in order to learn, it was really not water damaged, but very touched by someone else.

[mon2]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

Good work.

This is a common usb hub controller and you should be able to purchase another from many distributors of Microchip parts.

Yes, it should be safe to leave it out of circuit and power up to see if your voltage rail remains at +3v3.

[marce002]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

Wow thanks mon2 it gave video!!! I will have to order that USB chip and maybe check those resistors you va mentioned because I did the UC first I do not know why.... but anyways it is working.... again thank you very much for your excelent an fast comunication!!!!

thanks from buenos aires argentine

[marce002]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

Ok finally replaced the chip USB2513 and keyboard and trackpad now works... note that this chip is responsable for them also bluetooth was not working while it was removed....
Only minor deffect is that I can see small horizontal lines i do not know if you call them glitches after resuming from sleep or closing the lid.... maybe has to do with a chip that I took off before the USB2513 , the one called: u2752 74LVC2G08GT, and maybe it is not well soldered back or ruined....



thanks and that was my last quiestion, no longer bothering....regards

[mon2]

Re: Macbook a1466 not entering S3 PP3V3_S3 1.73v at R7811

Good work!