HP 50g & SD Cards: Performance, Format, Notes

[matthiaspaul]

(09-02-2016 11:27 PM)JDW Wrote:  But if you watch my video, you will see that I used a Fluke meter set to Continuity Check and then touched one probe to the pad associated with R68 and then touched the other probe to the metal frame of the SD card socket. I must assume that the metal frame is always grounded.

The metal frame of SD card readers is grounded in some cases, but definetely not in all cases. It all depends on the specific SD card reader.

When not connected to GND, it may be floating, connected to the card's supply pin or connected to one of the switches (in this case, the frame is used to save the space necessary to route that switch signal to a pad located elsewhere).

Greetings,

Matthias