Repair LCDs Tandy EC-4025 (TI Collegiate)

[John Cadick]

I have a Tandy EC-4025. A couple of the LCDs have lost some segments.

1. Anyone know anything about the Calc?
2. Anyone have any tips on repairing/replacing LCDs?

This calc is identical to the TI Collegiate.

Pictures are available if anyone is interested.

TIA - John

[jebem]

(09-23-2017 01:16 AM)John Cadick Wrote:  I have a Tandy EC-4025. A couple of the LCDs have lost some segments.

1. Anyone know anything about the Calc?
2. Anyone have any tips on repairing/replacing LCDs?

This calc is identical to the TI Collegiate.

I gave a couple of the Texas variants. They can be acquired for low cost here in Europe (10 to 15 Euros for a used in good working condition machine).

Never tried to open them.

But in these machine generations, usually the lcd uses a cheap unreliable flat cable built from plastic where composite conductive material is deposited to make the trace wires.
This kind of conductive material will brake with aging.
I have fixed other models by simply applying hot air over the flat cable. I just use a regular air drier as the tool.

I have posted here before this technique applied on a Casio but can't find the message.

[John Cadick]

Thank you very much, Jose. I'll try the dryer on it to see if that helps. I am hesitant to try to operate on it. 72 year old fingers don't work as reliably as they used to. 8^}

John

[Steve Simpkin]

That's a very interesting design.
http://www.datamath.org/Sci/Modern/Collegiate.htm

[John Cadick]

I really like the way it is designed. And it has complex number support. It looks like it may open fairly easily. Sounds like I may have a Sunday afternoon project tomorrow.

Thanks, Steve.