Unexplainable External Display Issue

[LegacyUser12]

Situation
MacBook 5,1 (Late 08 C2D 2.0ghz) High Sierra 10.13.6 (dosdude1's patch)
Mini-DisplayPort to VGA external monitor has been working fine for years.

Issue
Suddenly my MacBook does not detect external displays.

Literally the only thing that has changed between the last time an external display worked and now is I am staying with boyfriend due to COVID (nurse & LEO).

Cause?
Perhaps I accidentally fiddled with some sort of permission, deleted/moved/screwed up a file?

Attempts to remedy thus far include:
- SIP is DISABLED
- reset PRAM & SMC
- tossed blocker extensions to the curb
- BF's brother has a 2012 MacBookAir, double checked the functionality of MDP->VGA adapter & VGA cord with his and it detected with no issue whatsoever.
- many hours on internet trying to find ways to troubleshoot
- annoying dosdude1 via email (sorry!!!)
- running out of my favorite top shelf rum

I haven't needed a 2nd display for several months but with a new job I really need the extra screen for multitasking across spreadsheets.


Anyone down for troubleshooting just let me know what system reports/info are needed.
I ran this tool and have the file ready - Plugdebug-macOS-0.10.0.app

 

[avz]

It is possible that the mini-DisplayPort itself failed(hardware). Dosdude1's patch is irrelevant and can't cause any issues as your hardware is natively supported by High Sierra. I have the very same MacBook5,1(Mojave 10.14.6 installed) and don't have any issues with an external monitor(fullHD 43 inch Sony Bravia TV).

 

[LegacyUser12]

It is possible that the mini-DisplayPort itself failed(hardware). Dosdude1's patch is irrelevant and can't cause any issues as your hardware is natively supported by High Sierra. I have the very same MacBook5,1(Mojave 10.14.6 installed) and don't have any issues with an external monitor(fullHD 43 inch Sony Bravia TV).

Friday at a computer store I used a mini-DisplayPort to VGI adapter to test out a monitor and it worked there fine.

 

[avz]

Friday at a computer store I used a mini-DisplayPort to VGI adapter to test out a monitor and it worked there fine.

VGI? or DVI? or VGA?

I always dual boot my system with different Mac OS(Mojave, Mavericks). This allows to rule out any software issues in a matter of minutes by rebooting in a different Mac OS.

If your MacBook worked in a computer store with a different adapter/cable and monitor this means that the issue is with your adapter/cable(it is very common for these things to be intermittent) or monitor(input jack can also become loose over time).

 

[LegacyUser12]

VGI? or DVI? or VGA?

I always dual boot my system with different Mac OS(Mojave, Mavericks). This allows to rule out any software issues in a matter of minutes by rebooting in a different Mac OS.

If your MacBook worked in a computer store with a different adapter/cable and monitor this means that the issue is with your adapter/cable(it is very common for these things to be intermittent) or monitor(input jack can also become loose over time).

Adapter/cable ruled out as issue because...
1. they both work on a different MacBook
2. got an Apple mDP->VGA official adapter and it does not work
Monitors work with other computers
Input/mDP itself: I think you are onto something see below.. No Signal Message.

+ New Observation #1
If either monitor is connected to ONLY power NO VGA input connected
The screens are on as expected with the usual "hello the lights are on, I'm home, doors unlocked, come in (aka connect the cord)"
If either monitor is connected to BOTH power AND VGA input connected
Then the screens go from the usual "hello" to "lights are on but nobody cares" No Signal Message.
Once I remove the connection, the No Signal Message reverts to scrolling message as before.

Observation appears to be that there is some sort of 'handshake' occurring with the VGA cable & APPLE OFFICIAL mDP to VGA adapter between mDP port from MacBook to VGA input of monitor(s).
[note: the 2 monitors I have with me only have VGA]

+ New Observation #2
If I use a working mDP to HDMI (tested on other MacBook and previously worked for this one) to a Samsung TV (worked previously), select the appropriate HDMI input, I get No Signal Message
Once I remove the connection, the No Signal Message reverts to select input.
Observation appears to be that there is again some sort of 'handshake' occurring with the cable/adapter between mDP port of the MacBook HDMI input of Samsung TV. [note: neither MacBook have direct HDMI ability to test without an adapter, also Samsung TV used works 100%).

*again APPLE official mDP to VGA adapter, all peripheral components WORK with other MacBooks*

And why can't I boot into safe mode?
-sudo: nvram: command not found
-nvram: Error getting variable - 'boot-args': (iokit/common) data was not found

 

[avz]

Ok, looks like I misunderstood your post #3. What exactly did you test at the computer store? Your mini-DisplayPort to VGA adapter? Your monitor? Your MacBook?

As I already suggested it would be mighty helpful if you can boot your MacBook say to Mavericks and see what happens. If it works, you might have to reinstall High Sierra.

"Command not found" usually means that you typed the command wrong.

 

[LegacyUser12]

Ok, looks like I misunderstood your post #3. What exactly did you test at the computer store? My MacBook 5,1 with a mDP->DVI adapter (my apologies for the VGI typo in previous posts) to one of the (used) store's Dell P1911
Your mini-DisplayPort to VGA adapter? No.
Your monitor? Yes; I have 2 Dell P1911 monitors at home and I tested one in the store.
Your MacBook? Yes.

As I already suggested it would be mighty helpful if you can boot your MacBook say to Mavericks and see what happens. If it works, you might have to reinstall High Sierra.
What is the most conducive way to test outside High Sierra on the system in question? USB installer and boot to a partition? I'm unfortunately just knowledgeable to be dangerous at this point.

"Command not found" usually means that you typed the command wrong. Negative.

 

[avz]

If your MacBook worked at the computer store, it is totally fine. I would have to look at your setup myself to do any more troubleshooting.

 

[AdIonascu]

Might be a resolution-related issue, you've said you have reseted NVRAM with no success, try to swictch between extended and mirror display (press CMD+1 on your keyboard and see if there is a change). You may check in System Prefeences also, you should see the external display there.

 

[LegacyUser12]

If your MacBook worked at the computer store, it is totally fine. I would have to look at your setup myself to do any more troubleshooting.

I’ll send you whatever report/log/screenshot you can think of to assist

 

[LegacyUser12]

Might be a resolution-related issue, you've said you have reseted NVRAM with no success, try to swictch between extended and mirror display (press CMD+1 on your keyboard and see if there is a change). You may check in System Prefeences also, you should see the external display there.

I think I tried that but not in safe mode as I can’t boot to it (shift on restart, tried command line too) I get the prohibited circle with diagonal line—I presume since I’ve used 10.13.6 patch High Sierra on an unsupported model. —- am I wrong? Can unsupported models using patched OS boot into safe mode?

System preferences—no. I’ve also acquired some command lines to obtain connected hardware and no avail.

idea—revisit nvidia drivers?
idea—crack her open & check logic board connections?

 

[AdIonascu]

I think I tried that but not in safe mode as I can’t boot to it (shift on restart, tried command line too) I get the prohibited circle with diagonal line—I presume since I’ve used 10.13.6 patch High Sierra on an unsupported model. —- am I wrong? Can unsupported models using patched OS boot into safe mode?

System preferences—no. I’ve also acquired some command lines to obtain connected hardware and no avail.

idea—revisit nvidia drivers?
idea—crack her open & check logic board connections?

No and no, try to get a native working OS (10.11.6) on an external drive and see if the issue persist, if not, I'm afraid you have to reinstall OS on your machine.

 

[LegacyUser12]

No and no, try to get a native working OS (10.11.6) on an external drive and see if the issue persist, if not, I'm afraid you have to reinstall OS on your machine.

Not necessarily afraid. Last night I was contemplating should I reinstall..

1. Switch from HFS to APFS

2. Take a go at Mojave (I have studied the threads about 10.12 vs 10.13 vs 10.4 on the 5,1 & other unsupported Macs)

I’m replying from my iPhone while cooking but I will come back and post specs so you guys know exactly what hardware I have.

 

[avz]

I’ll send you whatever report/log/screenshot you can think of to assist

You are overthinking this.

So you took your MacBook to the computer store and asked the store to provide you with the monitor and adapter, right? The store gave you the monitor and adapter, you tested your MacBook and it worked, right? If the answer is yes then the issue is solved.

Adapters and cables can become intermittent over time(you bend the cable/adapter one way - does not work, bend it the other way and it starts working). Have you tried wiggling and bending your adapter/cable to see if it makes a connection?