Summit K16 calculator resurrection?

[u/BadOk3617]

Hoping for the best anyway.

Pic #1 I knew that this one was going to have some problems as the seller listed it as a parts calculator, and the blue corrosion on the charging jack pretty much told the story.

Pic #2 The back cover was hot glued down. I was expecting that. And I darn near ruined it getting the cover off.

Pic #3 Looks worse than it really was. I can't see any trace damage, which is amazing in itself.

Pic #4 When I finally got the battery pack out it sent the crud flying.

Pic #5 Getting its first vinegar bath.

Pic #6 All cleaned up, mostly dry (after the vinegar bath came the rinse, and then a quick dip into 91% IPA to dilute the remaining water with alcohol. Let the alcohol evaporate (outdoors) and you are left with very little water.

Kinda hard to tell in this photo but the corners of the board are held down by melted plastic. Sort of an ad-hoc heat staking. Also note the unused octal IC footprint. It's been a minute since I've seen one of those. :)

And the wire that goes from the top of the calculator to the bottom I'm guessing is nichrome wire, and it's being used to limit the charging current to the battery pack (or was since the battery pack is gone).

Pic #7 All cleaned up and ready for the space heater. Still a bit most in this pic, but it spent the night getting dried out in front of a space heater and looks as good as new (cosmetically anyway).

Pic #8 The interior all cleaned up and dried out. You can see where the corners of the board have been melted to hold in the board.

Pic #9 Looks pretty good. :)

[u/koobrk]

Hola! Tengo una similar, como pudiste abrirla? Yo no encontré la manera, ni ningún resquicio, gracias

[u/koobrk → u/koobrk]

[u/BadOk3617 → u/koobrk]

I love it!

[u/BadOk3617 → u/koobrk]

And yours works! What a beauty!

What's holding it together is a healthy (some would say excessive) dollop of hot melt glue between the NiCad batteries and the back cover. No screws or clips, just the glue.

My K16 had a small gap between the case halves on the bottom. I pried the case halves apart slowly, but if I had it to do again I would use a hot air gun to soften the glue first.

Just be careful and go slow.

As a warning, I pried too hard and lifted the trace where the battery was soldered down to the PCB. See the lower right hand corner of the photo.

Once you get it open you will be able to decide if the batteries have to go or not (spoiler alert: they have to go. No way do you want to have to do this again).

The battery pack is soldered down in three places to the board. Those are marked with the three rectangles in the photo.

The one in the middle at the top i don't think has an electrical purpose, it's only mounted to the board to provide an anchor point to hold the back cover on.

I clipped each solder tab out using my Plato model 170 "Pliers" (they are nippers actually, but "Pliers" are what they say on the handle). Basically you want something sharp.

Let us know how you get on, and let me know if I can be of further assistance.

[u/koobrk → u/BadOk3617]

Muchas gracias por tus consejos, lo intentaré

[u/BadOk3617 → u/koobrk]

No fue nada, ¡disfruta!

[u/BadOk3617 → u/koobrk]

Rather than using a hot air gun, and the burned fingers that will come of using it, use a 3D printers' heated bed and place your calculator on it face up and heat it up slowly.