HP-42S - Is this internals picture normal?

[Diego Diaz]

Hi Weenis, and welcome!

The 42s board in the picture is perfectly normal.

The upper unused pads, seems to be intended for yet another capacitor but I've never found it populated.

The other empty smaller pads are for a glass encapsulated Schottky diode which is an alternative to the TSOP plastic diode that you can see in your board. Seems that HP decided to keep both posibilities available and I've found boards with glass diode or TSOP indistinctly.

Hope this helps.

Diego.

BTW, Since you've had to open your 42s why not take the chance and replace the original 8K RAM chip with a new 32K one?