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Computer was working fine except for old battery and a broken key on the keyboard. Ordered a new topcase and battery, swapped everything over…
The machine will power up but there’s no chime.
fans spin, caps lock works. but the display shows nothing and no backlight.
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I had a similar thing happen with a repair I just did on a 2015 MacBook Pro Retina. Did the screen replacement just as I did with all others in the past, and in trying to turn it on it had no life. An SMC reset (Hold Shift+Control+Option+Power button) was able to get me fan spin and the keyboard backlight, but no picture.
I am not sure if there is some sort of sensor that can make the Mac tell when the screen is open or closed, but when I had just about given up on it I closed it and noticed that the Apple logo on the back was lit. I opened it and saw the display was functioning fine. I’ve noticed that sometimes I have to close it and wait for the backlight to come on before I can use it. After a week or so it started functioning normally.
TLDR; Just do an SMC reset and then give it some time to power on, and try opening and closing it until the screen turns on. Not sure if my situation was an isolated incident, but this is what worked for me. I hope this helps!
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@j__ - Thats Good! But, still not great ;-{
So that implies we either have a blown fuse on the backlight power line or the backlight logic on the logic board is damaged.
Do you have a DVM so we can check the fuse?
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I do not, unfortunately. Is the fuse on the logic board even replace-able?
Yes, while not easy, its a small SMT device. It's the easiest to replace.
Sounds like you need to visit someone with Mac and soldering small SMT devices skills.
I can do it with a part number and a location on the board...
@j__ - Which version of graphics do you have? The intergraded (IG) or the discreet (DG)?
I have the DG one
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Are you able to see your desktop using an external monitor?
door Dan
I don’t currently have one...
I’ll work on getting a cheap one but most stuff around me is closed because of Covid so I’ll probably have to order one just for this purpose...
There’s no backlight either. So I’m going to check the LVDS assembly? The backlight is powered through that cable, right?
The no chime thing is disconcerting, but the charge cable starts with a green light and then switches to orange, so some of the charging logic appears to be working as well. Or at least that’s how I take it,
Otherwise... what else do you think it could be? Toasted logic board somehow? Seems unlikely from this specific repair unless I inadvertently broke a trace somehow getting it back in. It takes a little force to get the ports in place but I don’t think I applied a dangerous amount of force .
door John
after I woke up from my anger nap, I had an idea…
the machine appears on my WiFi when I power it on. So the logic board is alive. Just the display is borked.
i also took it back apart (20 minutes this time woohoo) and checked the lvds assembly which seems to be firmly attached to the display so I don’t think it’s that either.
door John
You don't need to buy a display, you just likely need a adapter cable so you can plug your system into your TV's HDMI port. You should be able to order one online.
OK, let's try one other way to check the display, lets place a flashlight on the display at a sharp angle are you able to see the faint image of your desktop and its icons?
door Dan
@danj I shined a flashlight through the Apple logo in the back, and I can see an image. So it’s a backlight issue...
If he computer thought the lid was closed, would the display not work at all or would it simply have the backlight off (as here)
It appears to be giving the filevault recovery screen.... but I can only see the very center... resetting NVRAM got me back to my login prompt which I can now use and can see (the center of) my desktop.
door John