Original Magsafe 2 charger 60/85W for sure???
Post U7501 basic voltages; 23, 12, 13, 22, 29, 21.
Post U7501 basic voltages; 23, 12, 13, 22, 29, 21.
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820-4924 problens
- Thread starter tlough75
- Start date
tlough75
Member
I am so sorry I wasted your time on this one. I ignored the basic rule to pay attention to corroded components, or components with gray end caps. I found another forum post where the person had the same problem on an 820-3437 board. The PP3V3_S5 rail was shorted. They measured the coil (L7560) and found that a cap or two was shorted. So I decided to measure the same coil on my board well lo and behold PP3V3_S5 was short, by the same caps. they were C3280 and C3281 respectively, and are located close to the LCD connector. The end caps were gray but didn't look too bad. well once I took them off, the short was gone. Put some replacements from a donor and now we have fan spin and a ? folder. i should have known better since these two caps are tied to the mic connector which burnt up. lesson learned.
You've repaired it and learned a lesson too.
It is not waste of time, nor even for me.
It is not waste of time, nor even for me.
Post U770 voltages, 5, 18, 17, 15, 16, 11.
Also check diode mode to ground at both A/K pins of D7710; w/ and w/o LCD connected.
Also check diode mode to ground at both A/K pins of D7710; w/ and w/o LCD connected.
In the time you have 5V at pins 28-30/J8300, check if LCD_HPD_CONN and DP_INT_HPD go both high.
"Put some replacements from a donor and now we have fan spin and a ? folder."
Did you get image and backlight that time?
And now nothing at all?
"Put some replacements from a donor and now we have fan spin and a ? folder."
Did you get image and backlight that time?
And now nothing at all?
tlough75
Member
So I timed how long it takes for the 5V to show up on Pins 28-30 on J8300 and it is about 10 seconds before it comes on then stays fr about 10 seconds before dropping to 0. I noticed on the two tests you wanted me to do the millivolt digit on my DMM would dance between 1 and zero at the 10 second mark, then stop.
If these lines stay low, PCH cannot recognize LCD.
Try known good compatible LCD assembly.
Try known good compatible LCD assembly.
At least LCD_HPD_CONN should go high (2.5V), when you have 5V at J8300.
If not, bad video cable, or LCD panel.
Could also be a problem with LCD connector, if you already detected corrosion there.
Check all solders and traces...
If not, bad video cable, or LCD panel.
Could also be a problem with LCD connector, if you already detected corrosion there.
Check all solders and traces...
5V should come on for few seconds even if not LCD connected.
But it only remains on if PCH detects LCD.
That is only possible if DP_INT_HPD comes on; it requires 5V above mentioned.
But it only remains on if PCH detects LCD.
That is only possible if DP_INT_HPD comes on; it requires 5V above mentioned.
tlough75
Member
I fixed it!!!! don't know how I missed it, but the two vias for pin 1 (PPVOUT_S0_LCDBKLT) were broken. FIlled the one that was barely broken with solder and ran a wire for the other. oh boy what a troll this was. Now all I have to do is wait for new mic connector to come, run a new pad for that and this will be a fully working board.
"51.81V on pin 2 of D7710"
That was the sign; broken LED strips circuit...
That was the sign; broken LED strips circuit...