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Repair LCDs Tandy EC-4025 (TI Collegiate)
09-23-2017, 01:16 AM
Post: #1
Repair LCDs Tandy EC-4025 (TI Collegiate)
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
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09-23-2017, 06:07 AM
Post: #2
RE: Repair LCDs Tandy EC-4025 (TI Collegiate)
(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.

Jose Mesquita
RadioMuseum.org member

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09-23-2017, 07:08 AM
Post: #3
RE: Repair LCDs Tandy EC-4025 (TI Collegiate)
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
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09-23-2017, 11:56 PM
Post: #4
RE: Repair LCDs Tandy EC-4025 (TI Collegiate)
That's a very interesting design.
http://www.datamath.org/Sci/Modern/Collegiate.htm
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09-24-2017, 03:01 AM
Post: #5
RE: Repair LCDs Tandy EC-4025 (TI Collegiate)
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.
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