HP-21 - Crazy numbers

[Maximilian Hohmann]

Hello!

(05-02-2019 08:56 AM)BusyCalc Wrote:  Is it then possible to immerse completely the main PCB in vinegar? Is it not hazardous for the chips or the coil?

How do you rinse it afterwards? With distilated water?

Yes, you can immerse the entire PCB in vinegar (no need to dilute either). It won't do any more harm than the leaked battery liquid already caused. I just rinse it with normal tap water. Then I use either compressed air (from the compressor in the garage) or a hairdrier to dry it. Or place it in the sun for the afternoon.

Some of the corrosion needs alkaline chemicals to dissolve. I have had some success with baking soda (plain "Backpulver" from the supermarket here in Germany). One bath in vinegar, one bath in baking soda and a final rinse. A bit like it used to be when one developed film in the dark room...

Regards
Max