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mac-n-sauce

macrumors regular
Original poster
Jun 25, 2012
209
2
Tampa, Fl
Hello all.

I would like to start this new thread to see if we can make it easier to keep track.
Dadioh had started a thread that has been going on for a long time and has some awesome info in it on fixing your MacBook Pro.

My current issue is a 2009 with no power. Magsafe does not light up at all
G3Hot is 1.15v instead of 3.42v.

I am currently checking the PBUS SUPPLY/BATTERY CHARGER circuit .
With no battery installed and magsafe only:
Q7000 and Q7001 get a fluctuating 16.4v-16.8v and appear to be operating correctly, just not getting steady voltage.
Q7020 is where the problem seems to be.
It has 16.4v on pin 5, .09v pins 1-4 which is wrong.

So my question is: Do I have a bad Q7020 or is the IC chip bad sense I am getting pulsing voltage through the other points mentioned?
 
Hello all.

I would like to start this new thread to see if we can make it easier to keep track.
Dadioh had started a thread that has been going on for a long time and has some awesome info in it on fixing your MacBook Pro.

My current issue is a 2009 with no power. Magsafe does not light up at all
G3Hot is 1.15v instead of 3.42v.

I am currently checking the PBUS SUPPLY/BATTERY CHARGER circuit .
With no battery installed and magsafe only:
Q7000 and Q7001 get a fluctuating 16.4v-16.8v and appear to be operating correctly, just not getting steady voltage.
Q7020 is where the problem seems to be.
It has 16.4v on pin 5, .09v pins 1-4 which is wrong.

So my question is: Do I have a bad Q7020 or is the IC chip bad sense I am getting pulsing voltage through the other points mentioned?

I think that you need to sort out the G3HOT issue before you can move to the charging circuit. G3HOT powers the SMC and the SMC can not communicate with the charger ISL6258A (SMBUS_CHGR_SCL and SDA) unless it has power. SMC is powered by PP3V3_S5_SMC which is same as PP3V42_G3H_REG which is G3HOT.
 

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I think that you need to sort out the G3HOT issue before you can move to the charging circuit. G3HOT powers the SMC and the SMC can not communicate with the charger ISL6258A (SMBUS_CHGR_SCL and SDA) unless it has power. SMC is powered by PP3V3_S5_SMC which is same as PP3V42_G3H_REG which is G3HOT.

Checked the D6905
Pins 4-5 have 15.95v fluctuating
Pin 1 Has 16.6v fluctuating
Pin 3 Has .30v steady which should be around 12.6v correct?
So would I be correct in assuming the D6905 is bad?
Why would the voltage be fluctuating?
 
Checked the D6905
Pins 4-5 have 15.95v fluctuating
Pin 1 Has 16.6v fluctuating
Pin 3 Has .30v steady which should be around 12.6v correct?
So would I be correct in assuming the D6905 is bad?
Why would the voltage be fluctuating?

D9605 is just a set of diodes and should not cause a voltage drop.
The only components between the magsafe adapter and D6905 are a fuse and 47 ohm resistor. This may indicate a bad magsafe adapter or a bad adapter sense signal returning to the magsafe.
Pin 3 will only have voltage when the battery is connected.
Pins 4-5 are connected and should match.
I think the voltage should be good enough to to provide power to U6990 and you should check the outputs on it.
 
D9605 is just a set of diodes and should not cause a voltage drop.
The only components between the magsafe adapter and D6905 are a fuse and 47 ohm resistor. This may indicate a bad magsafe adapter or a bad adapter sense signal returning to the magsafe.
Pin 3 will only have voltage when the battery is connected.
Pins 4-5 are connected and should match.
I think the voltage should be good enough to to provide power to U6990 and you should check the outputs on it.

I have an identical working board and I am working off the values I see there.
Both boards have no battery plugged in.

On the board the R6905 is running high at 62ohm instead of 47. I am going to replace now. I will get back to you shortly
 
I have an identical working board and I am working off the values I see there.
Both boards have no battery plugged in.

On the board the R6905 is running high at 62ohm instead of 47. I am going to replace now. I will get back to you shortly

OK, now I have a working 47ohm resistor.
G3HOT is now .55v(going the wrong direction)
I believe i have a bad R6995 dividing resistor. It is only 198k instead of 348K
 
Dividing resistor is good now. G3HOT is .29v :( So now what?

Fuse is good, diode is good, resistors good, still no 3.42v
 
I believe so, but i will compare with my good board tonight.

I replaced U6990 with known good component.

I get correct voltage in pins 6,8
but i am not getting 1.25v on pin 1 or 3.42v on pin 4
When I touch my multimeter probe to pin 1 green light comes on on magsafe.

Dadioh, any thoughts here? Is the U6990 not soldering right? There isn't anything left on the G3HOT circuit to check other than capacitors, but those rarely go bad.

By the way, pin 1 reads .70v when touched with probe and magsafe light turns green.
 
I replaced U6990 with known good component.

I get correct voltage in pins 6,8
but i am not getting 1.25v on pin 1 or 3.42v on pin 4
When I touch my multimeter probe to pin 1 green light comes on on magsafe.

Dadioh, any thoughts here? Is the U6990 not soldering right? There isn't anything left on the G3HOT circuit to check other than capacitors, but those rarely go bad.

By the way, pin 1 reads .70v when touched with probe and magsafe light turns green.

Sorry. Fall is a really busy time for me.

If the resistor dividing network is correct and u6990 is good then you should get 3.4v out. How did you solder the new u6990? Check that the solder joints are good and that the other devices in the circuit are good. Make sure the two caps have not failed short circuit.

I have never needed to repair this circuit before so I am not much of an expert here.
 
Sorry. Fall is a really busy time for me.

If the resistor dividing network is correct and u6990 is good then you should get 3.4v out. How did you solder the new u6990? Check that the solder joints are good and that the other devices in the circuit are good. Make sure the two caps have not failed short circuit.

I have never needed to repair this circuit before so I am not much of an expert here.

Well, I removed the dividing resistor and checked them and the measured correctly. Just put a new LT3470(U6990) on with hot air gun. Have correct voltage in but not G3HOT out. It was .15v
The capacitors seem to be ok. I tried with my multimeter to test them on a high ohm scale.
There isn't anything else on the circuit so I am kinda stumped.
Would a bad capacitor cause the problem in this circuit.

When I test the dividing resistors in the circuit with no power on:
The 348k measures 130k
The 200k measures 128k
With power plugged in
348k = 87k
200k = 151k
can a resistor be soldered backwards?
 
Well, I removed the dividing resistor and checked them and the measured correctly. Just put a new LT3470(U6990) on with hot air gun. Have correct voltage in but not G3HOT out. It was .15v
The capacitors seem to be ok. I tried with my multimeter to test them on a high ohm scale.
There isn't anything else on the circuit so I am kinda stumped.
Would a bad capacitor cause the problem in this circuit.

When I test the dividing resistors in the circuit with no power on:
The 348k measures 130k
The 200k measures 128k
With power plugged in
348k = 87k
200k = 151k
can a resistor be soldered backwards?

You can't measure the resistance with power on. The way a multimeter measures resistance is it applies a small voltage and measures the current that flows. With power applied it messes up that process so the numbers don't mean anything.

Also, resistors are not polarized. You can install them either way.

I am thinking that there is something else down stream of the G3Hot that is pulling it low. The bad news is that rail is used in a bunch of spots so it could be anything along that path. See attachment. Any of the circuits attached to that bus could be responsible.
 

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You can't measure the resistance with power on. The way a multimeter measures resistance is it applies a small voltage and measures the current that flows. With power applied it messes up that process so the numbers don't mean anything.

Also, resistors are not polarized. You can install them either way.

I am thinking that there is something else down stream of the G3Hot that is pulling it low. The bad news is that rail is used in a bunch of spots so it could be anything along that path. See attachment. Any of the circuits attached to that bus could be responsible.

Thank you.
Ok, so just start at the top of the list and check the circuits one by one?
I have an identical working board to compare values.
Do you know if it is possible with the Landrex board view file to search for specific points?
 
Thank you.
Ok, so just start at the top of the list and check the circuits one by one?
I have an identical working board to compare values.
Do you know if it is possible with the Landrex board view file to search for specific points?

The problem is they are all in parallel so unless you can isolate them one by one from the other circuits it will be very difficult to find the specific device responsible.
 
The problem is they are all in parallel so unless you can isolate them one by one from the other circuits it will be very difficult to find the specific device responsible.

Hello Dadioh. You are the main reason of me being a member on macrumors. Your advice about the fuse to get backlight working, helped me. Thank you .
I want to be good at repair mac.
I want to ask ,how you clean a liquid damage mac.
what are the products you use step by step.
 
Help with another liquid spill

Hi ALL

My wifes laptop (MBP 13 mid 2009 c2d 2.26Ghz) suffered a minor liquid spill. Now it won't turn on. I cleaned the motherboard with 97% isopropyl alcohol and checked the fuse by the magsafe and the other by the keyboard which all tested good. The magsafe turns green when pluged in. I assume the keyboard and/or power button is non functional so I bridged the pads and it did nothing. I tested the power from the pad and got 3.4V on the left one. What should I test next? Will the Macbook turn on with the keyboard disconnected or does it need to be connected for ground?
 
Hi ALL

My wifes laptop (MBP 13 mid 2009 c2d 2.26Ghz) suffered a minor liquid spill. Now it won't turn on. I cleaned the motherboard with 97% isopropyl alcohol and checked the fuse by the magsafe and the other by the keyboard which all tested good. The magsafe turns green when pluged in. I assume the keyboard and/or power button is non functional so I bridged the pads and it did nothing. I tested the power from the pad and got 3.4V on the left one. What should I test next? Will the Macbook turn on with the keyboard disconnected or does it need to be connected for ground?

UPDATE: Replaced the DC-IN Jack with known good jack and it continues wth solid green LED and will not start by bridging the pads (registers 3.4V)???
 
Hello all.

My current issue is a 820-2530-A 2009 with no power. Magsafe does light green G3Hot is 3.42v.

I am currently checking the PBUS SUPPLY/BATTERY CHARGER circuit .
With no battery installed and magsafe only:

Q7020 pin5 has 16.5v pins 1,2,3,4 has all 0.1v.
Q7021 pin5 has 0.1v pins 1,2,3,4 has all 0v

So my question is: Do I have a bad Q7020 Q7021 or IC chip is bad?:(
 
Lots of very intelligent people in here. Thanks for the enjoyable read, and good luck to all looking to repaire their macs.
 
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