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ian1035nr

Goofy Line on PowerBook 180c Display

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Howdy, everyone. I’ve been working on a PowerBook 180c and I’m about to tackle the part I’ve been looking the least forward to: recapping the LCD

 

Before I get into it, I’d like to get some confirmation is these lines are likely caused by faulty capacitors/damage from cap goo

Anything colour that’s adjacent to a window is coloured darker than its supposed to be, and these bands extend from one edge of the screen to the other, and they only happen where there’s the edge of a window with very light contents. 
 

I had found a post elsewhere with a similar-looking problem, but someone said it looked more like an issue with the display cable. 
 

The capacitors are getting changed regardless, but I’d just like an opinion on whether or not In should start searching for a replacement display cable

F434ECEF-F179-4F58-A34A-7B06AB7C776C.jpeg

8F801DE2-440C-4708-9C93-B1B33DA01500.jpeg

3BFBC85D-5FDE-478F-8D61-C1C69C2C7098.jpeg

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If it means anything, pretty much all my PowerBooks have this artifacting both colour and B&W (apart from my PPC 500).

I would assume this is almost certainly a cap issue as opposed to a cable issue.

 

One would imagine the lines would be fixed on the screen if the cabling was damaged. But please feel free to correct me if I'm wrong on that assumption.

 

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That’s exactly what I was thinking. Any damaged display cables I’ve seen resulted in very different forms of visual artifacting compared to what I’m seeing on the 180c

 

Thanks for chiming in, makes me feel better. I wasn’t keen on trying to find a display cable; 180c specific parts like that aren’t easy to come by

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20 hours ago, tokyoracer said:

 

One would imagine the lines would be fixed on the screen if the cabling was damaged. But please feel free to correct me if I'm wrong on that assumption.

 

Fixed lines would likely indicate a failed panel, not a cable problem. The cable doesn't have conductors that drive each scanline, but rather h/vsync and a few data / clock signals for each color R, G, and B.

@ian1035nr What you've pictured is called cross-talk, and while that's expected with passive-matrix screens (caused by charge-effects due to design limitations), the 180c has an active matrix panel. It shouldn't look like that. There could be myriad culprits, but the cable is certainly one of them. Re-cap the display driver board, as it sounds like you're planning, and see if it helps. While you're in there, re-seat the ribbon cable on both ends.

If it does end up being the ribbon, they can be repaired :)

Edited by sutekh

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Yes, that's it exactly, it's an active matrix panel that's acting like a passive matrix panel

I was trying to think where I've seen that kind of look before; it's been so long since I've used a passive matrix panel that I've practically forgotten what it's like! Last time I had used a PowerBook with a passive matrix screen was a 150 I had repaired for someone back in 2010.

 

A visual inspection of the display cable doesn't show any obvious tears or breaks, but I'm wondering if some cap goo might have gotten into the array of short cables that run from the screen itself to the control board. Any references I've seen to this phenomena resulted in the traces being eaten away and the screen having lines that were just missing, so hopefully I got to this before anything got under the cables.

 

Only problem now is finding out what caps are on the board. I had posted about it a while ago, but the only concrete I answer I got was as follows:
 

47 uF  16 Vx 4

10 uF 16 V x2

10 uF 25 V x2

The rub is that my screen has 7 caps in total at that end of the board, not 8, but there also wasn't any indication as to where those caps actually go. And the ones on there right now don't have any markings to aid in identification.

If only the 180c had been more popular, either during it's actual production run on in recent years with collectors. Other models have lists of the exact caps people bought from mouser/digikey. But oh well, c'est-la-vie, I chose to go after one of the (if THE least) popular model in the 1xx series of PowerBooks. Only thing left to do is work around the obscurity

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Quote

 

Only problem now is finding out what caps are on the board. I had posted about it a while ago, but the only concrete I answer I got was as follows:
 

There I can certainly help you! I just re-capped mine a month ago while I was in there fixing the cable and Mouser conveniently stores your order history:)

I ordered the following:

  • 4 x 47uf, 16v, p/n: UUL1C470MCL1GS
  • 2 x 10uf, 25v, p/n: UUL1E100MCL1GS
  • 3 x 10uf, 16v, p/n: UUL1C100MCL1GS

I like the Nichicon UUL series owing to their 5,000hr life rating.

 

Here a pic of the driver board I still had on my phone:

 

 

IMG_20200811_092350.jpg

Edited by sutekh

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Sutekh, you are an absolute legend. Thank you so much!

 

One last question:

There's these capacitors here that I've "circled" in red. Are these something I need to replace as well? I'm worried about them because they're running right next to the delicate ribbon cables 

180c Caps.png

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Just realized that those look nothing like rectangular, surface mount, electrolytic capacitors. And whoever had a 180c with gap goo in the cables likely had the laptop stored on its side, letting gravity slowly pull expelled electrolyte from the other side of the board into the cables. The fact that it took me so long to realize that is sad. I knew I was dumb/out of it, but I didn't realize the situation was this dire.

 

That makes my life easier, just going to grab the appropriate caps and get this thing fixed. I just found a Reddit post of someone with exactly the same same problem as my unit, someone in the comments apparently had the same issue and fixed it by replacing the electrolytic caps on the back of the board, so I'm hopeful.

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Yeah, that “shadowing” on an active matrix display is a classic symptom of bad caps. That display should be 100% fine once recapped. Another symptom sometimes is the display looking washed-out until the unit warms up (I have seen this on some old Compaqs before).

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Washing out is the symptom I usually see when an LCD has bad caps. I guess in those cases they take a while to store a full charge.

 

I ordered new caps along with a good soldering iron/hot air station combo. I've been making do with a large, ancient soldering iron for years but that's simply not going to cut it for these tight quarters.

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Be super careful using any heat near the LCD itself; it's very susceptible to damage and doesn't take much to distort the display or melt the layers.  Mask off as much of the LCD itself as you can with tin foil/Kapton tape etc when soldering and heating components.

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20 hours ago, Byrd said:

Be super careful using any heat near the LCD itself; it's very susceptible to damage and doesn't take much to distort the display or melt the layers.  Mask off as much of the LCD itself as you can with tin foil/Kapton tape etc when soldering and heating components.

Agreed.

 

Liberal use of some tin foil to reflect heat might be worth your time. Better yet, if you can get hold of a sheet silicone that's heat resistant (like them futuristic oven gloves).

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Way ahead of you guys, I have a silicone sheet for the occasion. This is also why I'm upgrading my soldering iron to something with a fine tip and controllable temperature. My current one has only one setting: hot as blazes, it's not at all suitable for this task.

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On 9/17/2020 at 9:19 PM, ian1035nr said:

Sutekh, you are an absolute legend. Thank you so much!

 

One last question:

There's these capacitors here that I've "circled" in red. Are these something I need to replace as well? I'm worried about them because they're running right next to the delicate ribbon cables 

180c Caps.png

I would also pay some attention to the right side of the board (in this image) - there's some residue / crustiness on the plastic and connections of the driver that may partly at fault (if the symptoms are appearing near there). A word of warning though: Clean lightly and gently. I have a passive matrix display that exhibits some 'banding' that is clearly caused by a compromised connection inside the plastic of its column driver. The silly thing is that I actually caused the issue because I was so focused on getting rid of electrolyte residue inside that driver, the IPA dissolved much of whatever adhesive is under that plastic. Ignorance is bliss until it isn't.

 

A light surface cleaning might be enough to deal with what's there.

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That picture isn't actually mine, I pulled it from this website:

https://oldcrap.org/2020/04/27/apple-macintosh-powerbook-180c/

I was at work at the time and didn't want to wait until I got home to snap a photo of my own LCD. My board is nice and clean there. Actually, the underside with the bad caps was pretty clean, too. Just a very small amount of residue around the cluster of caps. Which is probably why the screen still works as well as it does. The banding is annoying but there's no dead pixels or anything of the like.

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11 hours ago, ian1035nr said:

The banding is annoying but there's no dead pixels or anything of the like.


Mine has minor banding as well. As fragile as these things are becoming, I’m planning on simply letting it go until it gets significantly worse.

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I’m at the opposite camp, I know the capacitors are going to fail eventually, and I’d rather handle it now while the plastics are still in reasonable shape. I still use these vintage computers a lot; most of my homework in college circa 2011 to 2015 was done on my 170. 

I also want to reinforce the hinge mounts on the 180c with PL construction adhesive while they’re still in one piece. I did the same thing to my PowerBook 170 and 540c, and both are still great a decade later. 
 

Preventative maintenance now can save me a lot of trouble later

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I think my issue is that I'm not as confident with a soldering iron as you guys are. I feel like I have a better than even chance of taking a currently working display and making a mess of it if I were to attempt a recap, at least as my skills sit now. Reinforcing the hinge mounts is something I'd work on, however.

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16 hours ago, bigD said:


Mine has minor banding as well. As fragile as these things are becoming, I’m planning on simply letting it go until it gets significantly worse.

 

I have this dilemma as well; I have a good hand for soldering however there are times you have to weigh up additional damage vs. it "still works and doesn't look too bad".  The thought of cracking into an LCD alongside additional motherboard repairs isn't an essential consideration when restoring PowerBooks, unless you use it regularly and need a completely dependable Mac.

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I don't know if what I have can be called "confidence", I just wing it and pray it works out. That's how I've been fixing things for decades and somehow it hasn't bit me in the rear; yet.

 

These old machines are honestly a good starting point. Plastics are fragile, but component density is much lower. The LCD controller circuit is mounted beside the screen, whereas modern units have the board stuck to the back. The isolation provided by the side-mounted board makes it a lot easier to keep heat away from the panel and eliminates the risk of applying too much pressure to the back of the screen.

 

But, like Byrd said, it really depends on what you want out of a vintage Mac. Classic Macintosh computers aren't always the most stable things, even when fully restored, so plenty of people would rather just keep the machines as a display piece since they have little practical use.

 

I just feel bad for these old computers and want to bring them back to a fully operational status and use them as originally intended. Especially ones like the 180c that weren't especially well received in their day. Once the screen is repaired I'll be rebuilding another 1xx series battery pack so I can watch the colour LCD chew threw the battery in under an hour and get that genuine 1993 Apple experience

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