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IBM 5140 Convertible display problem

snuci

Veteran Member
Joined
Nov 22, 2012
Messages
1,308
Location
Richmond Hill, Ontario, Canada
Some time ago, I bought an IBM 5140 Convertible. I just recently got a power supply for it and fired it up for the first time. Sadly, it has display issues and I'm not sure if it's the actual display or if it's something else.

When I first turn it on, I see several random vertical lines that span across the width and height of the screen and then a single line of display that goes completely across the screen. It's not quite the height of a full line. I an see the memory counting and then hear two uniform beeps (don't know if they are long or short or if it matters). Then I see some vertical bars to the left of the screen and it then goes to some vertical bars on the center of the screen. Below are some pics.

IMG_4820[1].jpgIMG_4822[1].jpgIMG_4823[1].jpgIMG_4824[1].jpg

I've taken the computer apart and reseated all that I could. I also inspected it and it looks okay. I took the back off of the display and there's not much one can fiddle with in there.

Anyone have any ideas if it's just a bad display? Is it serviceable at all? I'd hate to replace it and have it not be that.

Thank you.
 

snuci

Veteran Member
Joined
Nov 22, 2012
Messages
1,308
Location
Richmond Hill, Ontario, Canada
Thanks for the replies guys. Modem7, I did take the display apart and tried to squeeze the cable and all ends of the display but it makes no difference. That's the weird part and what makes me think there could be a remote possibility it's not the display. There are 4 or 5 tantalum caps on the display board but the back had been varnished to protect the board and the caps couldn't leak if they wanted to (if tantalums do leak). The board looks as new as it did when it left the factory. Very strange.

billdeg, I might just have to do as you suggest but not knowing the computer in a working state, purchasing another for parts is a little more expensive up here because of the shipping. Coupled with the fact that there is a slim chance the display is okay, I think I'll just have to wait for another cheap one to come up on ebay and try my chances.

Thanks again.
 

mbbrutman

Associate Cat Herder
Staff member
Joined
May 3, 2003
Messages
6,248
I have noticed that my 5140 display has developed a new problem in the last few days too - just the top row of pixels is misbehaving.

When I took apart my screen (the upgraded one with both brightness and contrast controls) I noticed that the foam backing that protects the circuit board from shock had deteriorated into black goo. Figuring that was not good for the display driver chips I thoroughly removed all of it and inspected the surface mount chips for corrosion or bridges that might be just glitching the one row of pixels. No luck though ...

So it is back together and I'm going to live with it for now, but I'm also on the lookout for a replacement display or a junker machine to try out. I also have the technical reference manuals courtesy of RJBJR and I'll be digging through them to see if there is an obvious are that needs further debug.

In the wild dream area, a replacement *color* screen would be a seriously cool project. I'm not sure if color information is being sent to the LCD screen or not. But if it is then a replacement color screen with some interfacing logic might be possible.
 

FunctionalLimits

Experienced Member
Joined
Dec 29, 2013
Messages
174
Location
NY, NY, USA
I realize this is an old thread, but just in case anyone is looking for a replacement display, I noticed a functional one today on ePay for $29.95 or best offer. Item # 200972699105.
 
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