A1466 820-000165-A with low PP3v42

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

I have placed an order for the resistors and will arrive in 7 days. Will post an update once received.

[mon2]

Re: A1466 820-000165-A with low PP3v42

As per suggestion by @Piernov, the output of this regulator is very close to the target value. You should be fine to continue as-is. The voltage is only off by 0.03 volts.

Place back the fuse at ppbus_g3h if it was removed and proceed to test this logic board again.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

Thank you for your reply. I just saw your reply now. The part would arrive in a day or two. Would you want me to change it and then continue or continue as is?

[mon2]

Re: A1466 820-000165-A with low PP3v42

You should be ok to continue with the voltage as-is since the difference is very small from the target value.

If you have removed the PPBUS_G3H fuse, apply it back and check the voltage to ground of PPBUS_G3H.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

Before I connected the fuse, I checked the PP3v42 line again for the voltage, it is 3.371V which I believe is low and think that the resistors needs to be changed before putting back the fuse. What do you think?

[mon2]

Re: A1466 820-000165-A with low PP3v42

Yes, to me, this is low. Measure the resistance of the fresh resistors before soldering them onto this board. Double check the soldering after they are on the PCB. Then power up to check if the voltage is higher.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

Sure. Will do and keep you posted.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

The resistors came in today. Changed R7095 & R7096. Now L7095 shows 3.3998 V. I reconnected F7140 and check for PPBUS_G3H. PPBUS_G3H is 8.09V. Any pointers?

[mon2]

Re: A1466 820-000165-A with low PP3v42

Check the voltage to ground of SMC_RESET_L.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

Just one more thing. When i check PPBUS_G3H it shows at 8.15V and then rolls down to 8.09V. I shall post SMC_RESET_L shortly.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

SMC_RESET_L is 3.361 V.

[mon2]

Re: A1466 820-000165-A with low PP3v42

Remove the fuse on ppbus_g3h again and check if this rail remains stable or not.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

With F7140 removed,the voltage roll down is still happening at PPBUS_G3H. 8.15 V - 8.09 V.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

The voltage roll over is still happening without the fuse.

[mon2]

Re: A1466 820-000165-A with low PP3v42

Do not have the schematic in front of me but check the current sense resistor on this same rail used by the ISL device. Remove all power. Believe it is R7050.

Meter in lowest resistance scale.

Measure the resistance from the ISL pin on one side of the R7050 and with meter probe on the other side of R7050. Be sure to check at the ISL pins.

We are confirming that the start to finish trace for R7050 is valid.

What is the measured resistance? Is the value the same as shown in the schematic?

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

The current sense resistors R7121 & R7122 were missing. Replaced those. But still the voltage rolldown is happening. Any suggestions? ISL? There is no green light on the charger as well.

[mon2]

Re: A1466 820-000165-A with low PP3v42

Check that the pogo pin contacts are clean on your paddle (LIO) board that mates with the magsafe adapter. This is very important. Recommend to use a cotton swap or similar with alcohol to clean up each contact.

Also attempt to power up the logic board without a battery. Does this allow for the magsafe light to turn on?

Check that the bridge cable between the main logic board and this LIO board is solid and with no corrosion. These cables are relatively low cost to replace (821-1722-A).

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

The bridge cable looks good. The contacts also look good.

[bridges_4u]

Re: A1466 820-000165-A with low PP3v42

Hi mon2,

Checked the bridge cable as well.Looks good. Any suggestions?

[mon2]

Re: A1466 820-000165-A with low PP3v42

1) check the voltage to ground of the smbus pins used on the isl side that creates ppbus_g3h. These pairs are used by the SMC as well for communication of the ppbus_g3h voltage.

2) remove all power. Meter in resistance mode. Measure the resistance to ground of each inductor. Looking for low resistance readings.

Post each measurement.