Powerbook 140 with screen issues

[pintodave]

I managed to get an as-is PowerBook 140 for $35 shipped, seller reported it dead, but with my 3a PowerBook adapter it does power on and boot from the hard drive. The only issue it has is a very dark screen that brightness and contrast adjustment does not affect much.

The lights are good, and for a second or two after power on, everything lights up properly but a second before the happy Mac it goes dim. At the right angle, you can see what it is displaying.

Is this a cap issue, screen issue, or cable issue?

 

[bibilit]

Caps issue on the screen side if think

 

[pintodave]

How many caps am I looking at, for replacement? A dozen or so on the LCD and a dozen on the logic? I would like to make this an all tantalum repair, honestly. no more worrying about them all together.

 

[pintodave]

One more question. Are the Duo key caps the same as the 1xx? I have a spare duo 230 keyboard but the 140 is missing a key.

 

[Elfen]

Duo Key Caps are a bit smaller (its a "75%" keyboard") and flatter than the 140 key cap (which is supposed to be "Full Sized"), though the mating plastics will fit but it will look odd and funny on the 140.

 

[pintodave]

Well, I replaced the two caps on the inverter and I got some brightness back, but it is only decent with bright desktop backgrounds. Anything like the standard grey makes the image dim.

The brightness of the image is judged by how much black is being displayed.

Is it time to move onto the caps on the LCD assembly?

 

[Elfen]

You should look at the caps in the bezel, see if any of them leaked and decide to whether replace them or not, but they should be looked at.

 

[pintodave]

I'm not having much luck finding caps that will fit, even in aluminum canister package type....anyone have any experiance here? Techknight or uniserver maybe?

 

[Elfen]

In seeing what some have done with their recapping jobs, the most interesting was doe by Genie_Mac. He used Tantalum Caps but not the SMD/SMT type. He used the little bulb radial type, which are a bit smaller than the SMD/SMT type. To see his work, see his thread:  https://68kmla.org/forums/index.php?/topic/19821-mac-newbie-se30-vid-probnot-another-one/?p=200436

They are also cheaper than the SMD/SMT type as well.

 

[pintodave]

Alright. I went and replaced the 100uf cap on the LCD display and it's better now, but still having shadows/lines of any open windows, spread across the screen.

I ordered new caps for everything in the PowerBook off Mouser, as wells as some new caps for my Portable (all tants this time). I will update this in a week or so with progress, and sooner with pictures!

 

[Elfen]

Can't wait for the results. Post pics.

 

[pintodave]

Alright, here are some pictures!

Here is the laptop in the condition it was in when I got it.

Must have been a students laptop...

 

[pintodave]

Using 91% IPA, I got the case all cleaned up without maring or scratching any of the plastics. Came out quite well! The front edge where it looks like it was melted does bug me, I'll have to keep my eyes out for display plastics now!

I also have a parts keyboard on the way, which I will use to replace the missing "9" key.

 

[pintodave]

This is how the screen was from the get go. In the right lighting, you could navigate the OS.

After replacing the two capacitors on the inverter board with some good used caps, I was able to get an image, but nothing that could be readable with a dark background or a lot of black displayed on the screen.

This is with a light background so I could see what I was doing.

Changing the background to something darker, or the default grey, resulted in a darkened image, and a lot of bright stripes from the corners of windows.

Even with the brighter background, anything black on the screen leaves a shadow line from top to bottom, which you can somewhat see in this picture.

 

[pintodave]

And last but not least, some photos of the repair(s)

These are the temporary replacement caps until the new ones arrive:

I replaced the cap on the far right of the image below with a new tantalum that I had lying around. I didn't have any other caps to do the rest of the screen, so this picture was taken for reference, both for me and for others. The tantalum cap is a 100uf 35V, the rest of the caps have their values still printed on them.

These are the rest of the caps to be replaced, towards the bottom left corner of the LCD screen assembly.

This right side was the worst of the hinge posts. The innermost post actually broke apart during disassembly, but the brass insert stuck to the screw. With some patience and some JB weld, I was able to rebuild the posts and strengthen/reinforce the other posts on the display housing.

Even after replacing only that ONE capacitor with a tantalum, I was able to get a better image with dark backgrounds. This is with the default grey background.

The only difference I am seeing, aside from being brighter, is it now takes about five minutes for things to "warm up". The display starts out dark upon power on, but slowly gets brighter and the contrast has to be adjusted to compensate.

I am hoping the new caps will fix all of this!

 

[Elfen]

This looks great! I'm learning a lot here.

But one thing is for sure, everything has a common denominator: Those damn faulty caps!

 

[pintodave]

No kidding!

On my first laptop, PowerBook 160, I remember the screen being green with a lot of ghosting. I was expecting the same with this. Why was the lighting green on the 160 i had?

 

[pintodave]

If anyone needs keys for a PowerBook 1xx keyboard, let me know. The only one I need is the number 9 key!

 

[techknight]

I have a ton of parts machines. I likely have keyboards