Big Yellow Stripe on PB150 Display

[Scott Baret]

As I got my PB150 out today to prepare it for the tutoring that I will be doing with it (which also happens to be my RetroChallenge project this year), I noticed a big yellow stripe about the width of a piece of masking tape along the right hand side of the display. It covers the hard drive icon and both System 7 menus, but is only on the top part of the screen and only in this small portion of the screen. The machine works fine otherwise and the yellow stripe really doesn't get in the way of anything I want to do with the computer (the programs I will be using with it were designed for 512 x 342 and are contained to a window in the middle of the screen), but I'd like to know what this is and how to fix it.

 

[Bunsen]

If you squeeze the bezel between thumb and fingers near the discoloration, does it go away? This would indicate a loose connection.

 

[Scott Baret]

I tried this today to no avail. Are you referring to pressing along the screen side of the bezel or the side of the computer?

The strange part is that touching this part of the screen doesn't present the typical effect of rubbing a finger across an LCD. Normally, a "Jello"-type effect will be seen when one presses a finger against a screen. On this one, the yellow stripe doesn't show any ripples, distortion, etc--it's like it's a big piece of masking tape.

My next thought is to open this guy up and look at the connector. Any thoughts on this?

 

[Paralel]

Is it possible the liquid crystals somehow leaked out of that section of the screen without a crack being visible?

Any screen I've seen, regardless of how busted it is, has always exhibited the "jello" effect unless there weren't any LC present (having leaked out of a large crack in the screen, etc...)

 

[Bunsen]

along the screen side of the bezel

That. Are the edges of the discoloured area straight horizontal and vertical lines? IE, is it a rectangle that aligns with the screen edges? That would suggest a connector or ribbon failure perhaps - specific lines and/or rows of the LCD getting bad signal. I would guess having a look at the connector is your next best step.

 

[Byrd]

I've had recently success using the "proper" electrical cleaning solvent in properly cleaning a fine video connector used in a laptop. However, having seen what you have described, if not a loose connection this isn't repairable - I've had a PB100 do a similar thing, sort of like a vertical line of dead pixels that have given up the ghost.

JB

 

[LCGuy]

From memory this is a common issue with PB150s, something to do with the display :-/

 

[Scott Baret]

After reading over the past few posts, I think I'll do the following:

1. I'll take the machine apart and fiddle with the connector.

2. If that doesn't do the trick, I'll take a picture and see if anyone can offer insight--or if it's a display problem as LCGuy suggests (given the low quality of the displays in these computers, I'm going to guess he's right that the display is the actual problem).

3. Should the computer be faulty, I'll probably look for a 190 to use long-term--more power, probably costs about the same used these days, and uses IDE for a hard drive connector. Hopefully the screens are more reliable in the long term--I want to keep with a 680x0 but like having IDE as a bus since the hard drives are easier to find and less expensive. I'll also keep the 150 around in case I find someone selling a replacement screen or if I find a 150 with a beat-up case (I saw one on eBay yesterday and am considering getting it).

Testing will take place on Monday. I'll keep everyone posted.

 

[techknight]

well the LCD display would have a "jello" effect regardless if the buffer connection is bad or broken. no jello means no liquid left. its gone. leaked from a crack or separation of the glass substrate in that area. granted this isnt the same thing, but i had a sony LCD TV with same problem, come to find out, someone used an acidic cleaner on the screen, and it got up in between the glass substrate and ate away at the crystals. exhibiting the same effect.