HP-97 Weirdness

[Nick Taylor]

I have an HP-97 on my desktop which serves as my daily driver.

Every few months the keys in the 2,5,8 column behave strangely. Rather than entering the digits, they cause Error to print on the paper, cause the display to dim, and generally misbehave.

I was assuming that maybe there's some dust inside it, on the keyboard contacts and should perhaps rebuild it.

However, the weird thing is that if I switch it off for about a month, then when I switch it on again, all is well.

I don't know enough about electronics to diagnose this, but could it be some faulty capacitor, that once discharged results in the unit working correctly again.

Any thoughts as to the cause, and perhaps what you would do to fix it?

Thanks

Nick

[Randy]

Does it happen both on and off the charger?