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So, I bought a portable…
Posted by: imactheknife on 2023-12-19 09:01:40
So you don't have a backlight. No version of the brightness panel is going to work.
right. so no contrast slider either. Just non backlit. Ok, makes sense.
Posted by: 3lectr1cPPC on 2023-12-19 09:02:30
Yeah, it's still TFT Active Matrix so it doesn't need contrast adjustment.
Posted by: LaPorta on 2023-12-19 11:08:24
I was just basing this on your video showing the slider doing nothing. The above is correct, there is no “brightness” adjustment on the Portable…just contrast. That is all. The fact that your contrast slider doesn’t do anything…I thought that was your issue and thought that newer control panel might not be working properly. No idea why your contrast slider, with the correct control panel I sent you, doesn’t adjust contrast.
Posted by: LaPorta on 2023-12-19 11:10:30
Yeah, it's still TFT Active Matrix so it doesn't need contrast adjustment.
The Portable does have contrast adjustment. It works the way it should on my non-backlit.
Posted by: 3lectr1cPPC on 2023-12-19 11:22:14
Oh. Didn't know that! Good to know.
Posted by: LaPorta on 2023-12-19 11:39:49
Still doesn’t explain the issue with the OP’s machine. Perplexing.
Posted by: imactheknife on 2023-12-19 14:53:16
Still doesn’t explain the issue with the OP’s machine. Perplexing.
Yeah is it a big change? Or subtle change in contrast?
Posted by: LaPorta on 2023-12-19 16:38:35
Yeah is it a big change? Or subtle change in contrast?
Give me a bit to get mine out of mothballs, and I will show you the difference.
Posted by: desertrout on 2023-12-19 19:52:04
@imactheknife On mine it's very noticeable, the lowest end of the slider makes the display quite faint. FWIW I did see a difference in your video, but it was very minor - certainly should be more.
Posted by: imactheknife on 2023-12-19 20:24:33
@imactheknife On mine it's very noticeable, the lowest end of the slider makes the display quite faint. FWIW I did see a difference in your video, but it was very minor - certainly should be more.
Interesting, well i wish i knew if i had proper version of 6.0.7 on it, or of there is a more specific version for portable?? When i installed a chose under customization to do portable etc. i wish i had more memory lol.. maybe system 7 would be better??
Posted by: desertrout on 2023-12-20 09:55:20
Interesting, well i wish i knew if i had proper version of 6.0.7 on it, or of there is a more specific version for portable?? When i installed a chose under customization to do portable etc. i wish i had more memory lol.. maybe system 7 would be better??
I have doubts 7 would make a difference, and likely will drag without enough RAM. I'm using 6.0.8, seems good. This might merit a look at some docs to see how the contrast is being controlled... I'm not sure what the control panel is doing exactly, but it might be discoverable looking at tech notes and the schematics.
Posted by: imactheknife on 2023-12-20 19:32:51
I have doubts 7 would make a difference, and likely will drag without enough RAM. I'm using 6.0.8, seems good. This might merit a look at some docs to see how the contrast is being controlled... I'm not sure what the control panel is doing exactly, but it might be discoverable looking at tech notes and the schematics.
Would it be something on logic or lcd? It is recApped etc and working excellent otherwise
Posted by: desertrout on 2023-12-21 07:42:54
Would it be something on logic or lcd? It is recApped etc and working excellent otherwise
I honestly don't know - I'm not familiar with the LCD circuitry. There *are* caps on the panel but they're not so prone to leakage as on the 1xx PBs afaik. Others have recapped their Portable screens, but I'm not sure if it was to address contrast issues. I wish I could provide more certainty here. I can take a look at some docs later and see if anything becomes apparent.
Posted by: desertrout on 2023-12-21 08:24:37
So, the dev notes (https://cdn.preterhuman.net/texts/computing/apple_hardware_devnotes/Portable.pdf) describe the contrast control as a pwm signal from the Power Manager which is run through an rc network.

Here's the network in question:
Screenshot 2023-12-21 at 11.07.18 AM.png

I'd do an inspection around those components (which are over by the right-side keyboard connector), maybe some testing and extra cleaning. Possible there's some lingering electrolyte from C14 and C116 mucking things up.
Posted by: LaPorta on 2024-01-22 19:49:10
Did you ever get this sorted out?
Posted by: imactheknife on 2024-01-23 04:47:54
Did you ever get this sorted out?
No,,haven’t been back into it lately. Will have to take a closer look and see. Was hoping to get more memory for it but someone out bid on sleeze bay lol..
Posted by: LaPorta on 2024-01-23 05:36:44
What capacity are you looking for? Do you just have the built-in RAM now?
Posted by: imactheknife on 2024-01-24 15:11:05
What capacity are you looking for? Do you just have the built-in RAM now?
I just have the 1 meg on logic board
Posted by: LaPorta on 2024-01-24 15:16:08
I do have two (to my knowledge) 1 MB expansion cards that I’m not using since I have the Maceffects 8 MB board.
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