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a1502 820-4924-A Liquid Damage... no image, but boots when Magsafe plugged in
- Thread starter papalati
- Start date
They remove all RAM chips and CPU.
SMC is always in place and the only option to get SMC replacment; because it has firmware and is board dependant.
Lot of MOSFETs, caps and other small chips...
SMC is always in place and the only option to get SMC replacment; because it has firmware and is board dependant.
Lot of MOSFETs, caps and other small chips...
papalati
Member
That is awesome. I'll order some. I always read the most reliable boards were somewhere around 2015, but not sure. I think they said non-retina too, but any one I see on ebay always are retina.
By the way, I'm pretty positive that one of the issues, if not the main issue is the LCD connector. I say that because when I went to look at the video cable as you told me to do I noticed that on one side it looked like some plastic was missing. I looked inside the connector and a chunk of it had melted together inside the connector. Probably when the water hit it I think. I'll order a couple just in case something sets it off again to melt it.
So, going to order the connector now to get it here the fastest. Going to be later this week that I post an update at the soonest.
Thanks again for all your help so far. I'll talk to you later this week or early next week.
By the way, I'm pretty positive that one of the issues, if not the main issue is the LCD connector. I say that because when I went to look at the video cable as you told me to do I noticed that on one side it looked like some plastic was missing. I looked inside the connector and a chunk of it had melted together inside the connector. Probably when the water hit it I think. I'll order a couple just in case something sets it off again to melt it.
So, going to order the connector now to get it here the fastest. Going to be later this week that I post an update at the soonest.
Thanks again for all your help so far. I'll talk to you later this week or early next week.
You can get better price contacting that Aliexpress seller directly.
He has many other scrap boards...
He has many other scrap boards...
So you still have image, but no backlight?
Which pads have been damaged?
Which pads have been damaged?
Be sure is 2015 display.
Make stock of broken screens, with good backlight circuit; if you plan to repair more MacBooks.
Make stock of broken screens, with good backlight circuit; if you plan to repair more MacBooks.
papalati
Member
After getting a non-cracked lcd I have redone the measurement on BKLT_SD and I'm getting 12.4V now.
That is incorrect voltage.
Do you still have image on internal LCD?
BKLT_EN_R is high?
Is the new screen compatible 100%?
Do you still have image on internal LCD?
BKLT_EN_R is high?
Is the new screen compatible 100%?
papalati
Member
Remember I never had an image on the internal lcd. All I saw before on the cracked screen was the backlight working when I still had the good board. I was never able to see the image because the screen was cracked too much.
I did have an image before, but I only had an image only on the hdmi port and the display ports.
The screen I ordered was for an early 2015 retina a1502, I'm assuming it is 100% compatible.
Once I replaced the lcd connector and the replacement screen came in, I went back through everything you told me the first time. I got to where you told me to check the voltage at D7710 pins from before. There was 0V on D7710. So then you said, "With 0V on BKLT_SD, you should have voltage on D7710; post both pins voltage. " But now I have 12.4V on BKLT_SD.
Now you are saying that BKLT_EN_R is high... Is BKLT_SD the same as BKLT_EN_R?
Cause I didn't check BKLT_EN_R voltage...
I'm really confused now... and so close to giving up and going back to fixing game consoles. It was so much easier.
I did have an image before, but I only had an image only on the hdmi port and the display ports.
The screen I ordered was for an early 2015 retina a1502, I'm assuming it is 100% compatible.
Once I replaced the lcd connector and the replacement screen came in, I went back through everything you told me the first time. I got to where you told me to check the voltage at D7710 pins from before. There was 0V on D7710. So then you said, "With 0V on BKLT_SD, you should have voltage on D7710; post both pins voltage. " But now I have 12.4V on BKLT_SD.
Now you are saying that BKLT_EN_R is high... Is BKLT_SD the same as BKLT_EN_R?
Cause I didn't check BKLT_EN_R voltage...
I'm really confused now... and so close to giving up and going back to fixing game consoles. It was so much easier.
EDP_BKLT_PSR_EN (so BKLT_EN_R too) must be high and BKLT_SD must be low; different signals, but directly related.
Backlight also depends by the communicacion between PCH, LCD and U7701; two distinct buses, =I2C_TCON_SCL/SDA and I2C_BKLT_SCL/SDA.
Be sure to always have 3V at PP3V3_S0_EDP_R and 5V at pins 28-30 of J8300 (at least few seconds).
Backlight also depends by the communicacion between PCH, LCD and U7701; two distinct buses, =I2C_TCON_SCL/SDA and I2C_BKLT_SCL/SDA.
Be sure to always have 3V at PP3V3_S0_EDP_R and 5V at pins 28-30 of J8300 (at least few seconds).
papalati
Member
I have 3.3v at PP3V3_S0_EDP_R and I have 5V at 28-30 of J8300.
I started looking at the current sense and looking at boardview vs the schematic, which I can't read very well, but I think boardview and the schematic shows there should be a U5450. On my board, I don't have a U5450, I only have 6 pads and half a solder point is missing on pin 6 and solder on pins 1 and 2 look terrible.
Schematic does not say "no stuff" for u5450 that I can see.
Is u5450 missing?
BTW I think someone worked on this board before I got it... I say that because there's just some other weird stuff I've seen already. Scratch marks on the PCB etc.
I started looking at the current sense and looking at boardview vs the schematic, which I can't read very well, but I think boardview and the schematic shows there should be a U5450. On my board, I don't have a U5450, I only have 6 pads and half a solder point is missing on pin 6 and solder on pins 1 and 2 look terrible.
Schematic does not say "no stuff" for u5450 that I can see.
Is u5450 missing?
BTW I think someone worked on this board before I got it... I say that because there's just some other weird stuff I've seen already. Scratch marks on the PCB etc.
U5450 definitely not used.
There are few BOM options mentioned on schematic.
"I have 5V at 28-30 of J8300"
Is it steady?
If yes, DP_INT_HPD must be high and image present.
Post voltage and diode mode to ground on both I2C mentioned buses; wirh LCD connected.
Is EDP_BKLT_PSR_EN still missing?
EDP_PANEL_PWR_OR_PSR_EN seems to be present...
There are few BOM options mentioned on schematic.
"I have 5V at 28-30 of J8300"
Is it steady?
If yes, DP_INT_HPD must be high and image present.
Post voltage and diode mode to ground on both I2C mentioned buses; wirh LCD connected.
Is EDP_BKLT_PSR_EN still missing?
EDP_PANEL_PWR_OR_PSR_EN seems to be present...
"I2C_BKLT_SCL = 5V and 1.84
I2C_BKLT_SDA = 3.3V and 1.82"
You should get same voltage on both lines; check w/ and w/o LCD connected.
Be sure all 4 resistors R7750-53 are good.
"I2C_TCON_SCL or SDA - couldn't be found in boardview"
Seeing which connector pins are, easy to find them on boardview.
Sometime Apple doesn't keep identical signal names on boardview, like in schematic!
I2C_BKLT_SDA = 3.3V and 1.82"
You should get same voltage on both lines; check w/ and w/o LCD connected.
Be sure all 4 resistors R7750-53 are good.
"I2C_TCON_SCL or SDA - couldn't be found in boardview"
Seeing which connector pins are, easy to find them on boardview.
Sometime Apple doesn't keep identical signal names on boardview, like in schematic!
papalati
Member
R7752 measures 69 ohms when the power is off, but then when voltage is running it drops to OL.
And with no LCD connected:
I2C_BKLT_SCL = 1.9
I2C_BKLT_SDA = 1.65
Both of those pads were of the 3 damaged and needed jumper wires.
and
l2c-tcon_scl = 3.3v and 1.77
l2c-tcon_sca = 3.3v and 1.77
And with no LCD connected:
I2C_BKLT_SCL = 1.9
I2C_BKLT_SDA = 1.65
Both of those pads were of the 3 damaged and needed jumper wires.
and
l2c-tcon_scl = 3.3v and 1.77
l2c-tcon_sca = 3.3v and 1.77
Last edited:
"when voltage is running it drops to OL."
Diode mode with power???
I hope not...
Do you have now the same voltage on both I2C_BKLT_SCKA/SDA?
I don't know when you posted voltage, or diode mode.
Remember, diode mode always red probe to ground.
Diode mode with power???
I hope not...
Do you have now the same voltage on both I2C_BKLT_SCKA/SDA?
I don't know when you posted voltage, or diode mode.
Remember, diode mode always red probe to ground.