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Mac Portable Backlight Issue

oldpcguy

Member
I have been working on a friends M5120 Macintosh Portable and have been making slow but steady progress on bringing it back to life. The first step was a full system board recap. Then I discovered an open trace near the V1M module. Everything looks to be in working order except for the screen backlight.

This system was upgraded to have the backlight screen and twice I've seen the backlight come on for a brief moment (that's how I discovered it had been upgraded). Unfortunately I am unable to get the backlight to come on permanently. Posting about this system in another thread I was informed the "Brightness" control panel was necessary to turn on the backlight. After testing this doesn't seem to be the case (it also would be very un Apple like to require the end user to install the OS prior to being able to easily see what they're doing).

Does anyone have any suggestions as to where to start looking? The cable connector on the ROM board has been cracked but the wires appear to be solidly connected. Wiggling them doesn't change anything which leads me to believe there is a firm connection for the affected wires.

When I pulled the screen off and examined the connector I see some green stuff on it (see picture). Is this normal? Or could this be the cause of the issue? Given how it covers a lot of the connector it seems unlikely as I would think the screen wouldn't function either (aside from the backlight the screen has no other issues).

Display Cables.jpg
 

Paralel

Well-known member
Interestingly the repair guide for the Portable says: "Backlight does not operate - Use version 1.3 of Portable CDEV" so I guess the Portable control panel does have something to do with the backlight.

It's other suggestion is "Check inverter PCA connections & replace inverter PCA if necessary."
 
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3lectr1cPPC

Well-known member
IIRC 5120 portables with the backlight upgrade have a special expansion card that adds support? Is that present?
 

oldpcguy

Member
Interestingly the repair guide for the Portable says: "Backlight does not operate - Use version 1.3 of Portable CDEV" so I guess the Portable control panel does have something to do with the backlight.

It's other suggestion is "Check inverter PCA connections & replace inverter PCA if necessary."

I'll check the version. However, I am booting from a generic MacOS 6.0.8 floppy. Also, I installed this version to an external hard drive and then booted from there. Either way there is a Portable CP so I'll check.
 

oldpcguy

Member
IIRC 5120 portables with the backlight upgrade have a special expansion card that adds support? Is that present?

It is present. I think it's referred to as the "ROM Card". This is the card where the connector has been damaged. However I think I've been able to secure the two wires where the connector has broken off. Wiggling these wires doesn't result in the backlight illuminating.
 

oldpcguy

Member
Interestingly the repair guide for the Portable says: "Backlight does not operate - Use version 1.3 of Portable CDEV" so I guess the Portable control panel does have something to do with the backlight.

It's other suggestion is "Check inverter PCA connections & replace inverter PCA if necessary."

I just had an opportunity to check and I think it's version 1.2. I have little experience with MacOS 6.0.x so perhaps I'm not checking the right thing. I went into the "System Folder" and checked the version of the icon named "Portable". It reported version 1.2. Since this is a "stock" version of MacOS 6.0.8 I assume it doesn't ship with version 1.3. Where can I obtain this version? Or should I try a newer version of MacOS (such as 7.x)?
 

Paralel

Well-known member
I just had an opportunity to check and I think it's version 1.2. I have little experience with MacOS 6.0.x so perhaps I'm not checking the right thing. I went into the "System Folder" and checked the version of the icon named "Portable". It reported version 1.2. Since this is a "stock" version of MacOS 6.0.8 I assume it doesn't ship with version 1.3. Where can I obtain this version? Or should I try a newer version of MacOS (such as 7.x)?

You can get it from this mirror of Apple's FTP before they killed it off:


Here is the text for that extension:


It says it is specifically only for 6.0.7 & 6.0.8.

Hopefully that should do it for you.
 

oldpcguy

Member
Thank you for this. I've got it downloaded, now I just need to get it onto a Mac readable floppy.
 

oldpcguy

Member
I was finally able to get this CP onto a HFS disk which I could use to install on the external hard drive and...it solved the problem. Thank you Paralel for the advice and link to version 1.3. Here it is:

Desktop with Backlights.jpg
 
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