Question about Texas Instruments TI-85 Calculator

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My TI-85 has not been used since about 1995. I recently put a new suite of batteries into it, but it will not power on. Sometimes I get a black screen when I put the last battery in. Sometimes I get squiggly lines. But the screen is normally blank, just like it is off. I have tried adjusting the contrast, but this is not the problem. I cannot get the calculator to respond to anything. Any ideas?

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  • joel_slaton Nov 12, 2010

    Batteries were never kept in the unit to the point of corrosion. The calculator has not had alkaline batteries in it since November 1999 when I packed it away to move. The original lithium backup battery has been in the unit until I changed it a few weeks ago hoping to revive the calc. The battery contacts are clean, and I can measure 6v on the circuit board. A visual inspection of the pcb's shows no leaking components. I suppose its simply shot...



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I see noone has answered.I needto know something.Were there old batteries left in it for a long amount of time?If there were,they may have leaked and junked it out.Is there any discoloration on the contacts?Also,with an electronic device laying around for so long and not being used,the components within the circuit board may have just lost their value.Capacitors will easily go bad after 15 years of no use.If you ever do not use things for a long time,it needs to be used periodically and have the batteries removed as soon as it is stored.That also applies to A/C being cycled once a month during winter,both house and car,same for heat during summer,perhaps even twice a month.The squiggly lines is most likely an indication of circuitry gone bad.All I can suggest for a last hope is to leave it on for about a half hour in an isolated place in case something leaks.If it is a battery or a capacitor,baking soda will neutralize it and prevent it from corroding further.Greg

Posted on Nov 12, 2010

  • Greg McCarthy Nov 12, 2010

    Excellent analysis.The only thing left is the LCD screen.I am not sure if it loses it's ability to be excited by the votage over time without use though.Either way,it probably is shot.If you can determine what is input to the screen,you may find some bad solders.That's all I have.



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How do I lighten the screen on my TI 85 calculator, it is very dark, I just recently changed both batteries

Press and release 2nd, then press and release down-arrow. Repeat as necessary. If you go too far, press and release 2nd, then press and release up-arrow.

Oct 18, 2014 | Texas Instruments TI-85 Calculator

1 Answer

Ti 85 wont turn on, batts good, tried to adj contrast , still nothing

Are you sure the batteries are in correctly? They alternate negative/positive, positive/ negative and so on. The first time I put the batteries in, I didn't have them in correctly. You tried adjusting the contrast. Just try adjusting upwards. Sometimes it takes a little for The Ti 85 to come on or adjust right. The Ti85 is an old calculator and, may not work any more. I had my Ti89 for almost 20 years so, they are pretty reliable. If nothing has worked take out all the batteries including the small one in the back. Texas Instruments say's " leave them out for 5 to 10 minutes." I had to leave mine out for over a 1/2 day to get it to work.

Here is the battery reset procedure for the Ti 85.

Try a new set of AAA batteries.
  1. Adjust the contrast by pressing and releasing the [2nd] key followed by pressing and releasing
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  2. Remove one of the AAA batteries. Press and hold the [ON] key for 20 seconds. Reinsert the
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  3. Remove all of the batteries including the round lithium battery for 5 minutes. After the 5 minute

  4. period, reinsert all of the batteries and turn the calculator on. Adjust the contrast if necessary.

Just keep trying. Sometimes they can be a pain.

Dec 28, 2010 | Texas Instruments TI-85 Calculator

1 Answer

We put new batteries in the TI-85 but the screen is now black and it is very difficult to read.

Adjust the contrast. Turn the calculator on. Press and release the 2nd key. Press and hold the down-arrow for a few seconds key until the screen lightens. Obviously, if you go too far, press and release the 2nd key and then press and hold the up-arrow key.

Sep 18, 2010 | Texas Instruments TI-85 Calculator

1 Answer

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You can increase the contrast by pressing and releasing the 2ND key, then pressing and holding the UP key. To decrease the contrast, use the DOWN key.

Oct 21, 2009 | Texas Instruments TI-85 Calculator

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TI-85 Calculator's LCD Display if faded

I did a little research on the Texas Instruments Website  and here is the answer. 
Adjust the contrast by pressing and releasing the [2nd] key followed by pressing and releasing the up arrow; repeat as necessary. To adjust or lighten the display, use the down arrow.,23871,-1,0,&jtfm0=&etfm1=&jfn=ZG57C2FA762C0BEC303F5B74A9018844AE124A5516274A019AFE22BA90B20

Jan 13, 2009 | Texas Instruments TI-85 Calculator

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turn it on and immediately pull out the battery: fixed my TI-85 if not its ded :-(

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We have a fault with the TI-85 people are asking me how to make a square root and stuff!

You are going to have to reset it yourself and put new batteries in it.

Hope this helps - Josh Howard

Jan 24, 2008 | Texas Instruments TI-85 Calculator

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