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820-00163 Chimes but no video

bjf

bjf

Member
No spill.
Has 1.8V on vcore.
.850 on gfx vcore.
0V on PP5VR3V3_SW_LCD
3.4V on SMC_LID
won't respond to PRAM with internal or external keyboard.
Tested with known-good screen.
No lights on USB keyboard or USB drive.

Not sure what's left to look for.
 
bjf

bjf

Member
It's clean. Nothing damaged. The whole board is spotless. The one-chime thing is weird. PRAM reset doesn't work, no lights on USB peripherals. But the CPU is apparently working enough to turn on and chime once.
 
bjf

bjf

Member
There's definitely something deeper happening with this. 0V on PP5VR3V3_SW_LCD. LCD_5V_EN is at 0V. The fact that it chimes once but won't let me do a PRAM reset is really odd. I've tried with multiple setups to do a PRAM reset and I can't get it to happen. SMC reset works. I've seen this happen many times where a PRAM reset would get it going again and get the screen to turn on, but not necessarily where the computer chimes initially. Not sure what's happening.
 
bjf

bjf

Member
I haven't touched it. It doesn't seem like I'm getting that far in the process so I'm tying to rule everything else out first. I feel like it's failing before the BIOS would have an effect. It doesn't appear to be entering the boot stage at all. Not really sure though.
 
S

SMMRepair

Member
If it chimes, it's reaching the BIOS stage. Does it chime and PRAM reset with LCD disconnected by chance?

If no physical damage, I'd try a new BIOS. Don't just clean the ME on the same BIOS, use an entirely new BIOS.

edited for clarification.
 
Last edited:
bjf

bjf

Member
Ok, I switched the bios chip out from another 00163. I have the normal flash of the lights on the USB keyboard now, but still can't do a PRAM reset. With or without screen attached. No video with screen attached. If I put the original chip back on I get the chime (actual chime) again 1 time but no flash of the keyboard lights.
 
S

SMMRepair

Member
That's because you just swapped the chips...you did not load a known-good BIOS with FSYS & $SVS pulled from original file.
 
bjf

bjf

Member
It should still perform a basic boot sequence, and allow for tasks like PRAM. I'm just trying to get to that stage at this point. I want to first find out if it's the chip or something else on the board.
 
S

SMMRepair

Member
Nope, not necessarily. You're assuming that. I've seen several instances where a unit will NOT PRAM reset, and the issue was a bad BIOS. I've also seen a million cases where a BIOS prevents a chime at all; or allows a chime but no other boot progress; or a chime and partial boot; or a chime, partial boot and boot to SSD but not USB; or a chime and internet recovery, but no boot to SSD or USB; or a chime and boot but no trackpad/keyboard functionality. The symptoms are not set in stone when it comes to a corrupt/damaged/bad BIOS. There definitely is absolutely no guarantee that a board will chime if you simply swap another BIOS chip over to it; this is ESPECIALLY true for the 2015+ models...they just don't behave the same way as older models. They also don't always like a "clean" ME...a vast majority of the time they will only work (chime, boot) with their original ME region. Cleaning it kills boot a vast majority of the time.

You're going to drive yourself crazy until you do a proper BIOS test.
 
bjf

bjf

Member
Ok, got it. I'm not sure what the FSYS & $SVS is but I pulled the krid-area and hwc-area information from the original chip and put in on the new chip. Reading and writing was smooth. No change. The new chip has no chime and no boot. Not sure if there's something else I could do with that but that's the extent of my understanding. So to recap, the original chip would chime but have no boot and no led flash on the external keyboard. The new chip has no chime or boot, but does have an led flash on the keyboard.
 
bjf

bjf

Member
Any other suggestions for this one? I don't want to, but I'm about to let it go. I'm out of ideas.
 
bjf

bjf

Member
No Title

Is there a secret to opening this? I keep getting an error and then the download button errors out too.
 

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