|LCD repair tip: Missing segments on heat seated ribbon|
Message #1 Posted by McAllan on 11 Mar 2012, 2:50 p.m.
In my search for information about the ghosting on classics I've encountered a few repair tip threads.
One if the things I've read which I do not agree with is that general consensus is that missing segments on calculators with a heat seated ribbon cable to the LCD is not repairable.
Here I disagree. I've done it in the past and I can do it again.
At a flea market I bought this TI-30Xa for pennies and "of course" it has a defect (hence low price):
Missing segments in the exponent
Mostly you don't need new ribbons, specialized tools etc. All you need is the soldering iron and some heat resistant silicone rubber. You can get special heat resistant mains wire at most lamp stores. It's the highest temperature one with tinned cores you should buy as it has silicone rubber on the outside.
Put a small piece on your (cold) iron and heat it up. Now you can reheat the ribbon cable in a gently manner and it'll not stick to the soldering iron. Be careful you don't bend the cable on the PCB edge. Or just stop a millimeter before the edge to be sure.
As you can see - the missing segments are working again :)
If the fault is at the LCD end you probably need specialized tools. At least because the LCD isn't as heat tolerant as the PCB. On the other hand all the faults I've seen have been on the PCB end.
Yeah I know I'm a heretic using a TI as example but the technique is the same on all calculators with similar construction ;)