Texas Instruments TI-92 Plus Battery Acid Leak Repair

Everything breaks.
It’s inevitable.
I was lent this calc for calc class where the batteries were over 20 years old with the original batteries in them.  Unbeknownst to the operational functionality of the device, I tried everything to get it to turn on.  From using fresh new batteries, to scouring the web to see if there was some internal reset that could be done, but nothing worked.  So I informed the device’s owner that I will be opening it up to see wtf is going on.

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The first thing I saw was residual battery acid powder.  Battery acid spills are shit nasty, and need to be cleaned carefully.  You dont want that shit on your skin is all I’m sayin’, aigh?

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It looks like all the two batteries on one side leaked out.  Luckily, TI was smart enough to attach a sheet of aluminum foil…probably for EMF protection.
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I ended up carefully removing the aluminum foil and scraped off the acid with a buck knife.
You can see that the battery acid removed a nice chunk of layer off the PCB.
That circular area is the where the left-right-up-down thumb control is suppose to make contact.  I was afraid that the acid might have erroded the contacts, but luckily, TI used a good quality circuit board.

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The problem was that I wasn’t ready to run the ol’ buck knife on a board with already iffy contacts, so after searching on how to handle consumer cell battery leaks on equipment, I found out that Isopropyl alcohol would safely work.  So, after wiping the area with alcohol and cotton swabs, I was ready to run a POST.

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The first POST showed only a small sign of power, so I started cleaning the PCB battery contacts with the swabs and alcohol.  After a few more swabs, I was able to fully power on the unit and test all the buttons to make sure it all worked.  So far, it’s been working like new!

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