HP 21 not powering on - repair/troubleshooting advice

[dmh]

(01-27-2021 09:41 AM)aurelio Wrote:  

(01-27-2021 07:54 AM)dmh Wrote:  I've read about bathing before but wasn't sure exactly what was meant.

Do you mean submersing all the circuit boards and screen?!? Sounds scary.

What ratio of water and vinegar?

Thanks

Don't worry: the bath is a well-established procedure, especially for this type of machines...
You can read about on many other discussions on this Forum.
First take apart the display which does not need any treatment, then drop the printed circuit board in a tray containing a glass of water and 3 tablespoons of vinegar cooking (I use the apple one). leave it for at least one day, then rinse everything under the tap and let it dry for another day, better if on a sheet of absorbent paper.

Let us know
Hope this helps
Aurelio

What about the circuit board with the keyboard and front of the calculator? Can that be bathed too?

Thanks