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

[JDW]

It's seems I lost R68 sometime after I removed it a few days ago. And since my video isn't quite high enough resolution to see the silkscreen on it, and since I don't have a schematic, I don't remember what value it is. It might be 104 (100kΩ) from what I see in my video, but I can't be sure. Vtile, if your 50g is still open, can you check the value for me, please?

Anyway, I took a high-rez 50g PCB photo just now (with R68 removed).

I put my Fluke meter back into Continuity Check mode (which beeps when both probes are connected to each other) and put one probe on the round pad near R67 and put the other probe on the SD cart slot itself (metal) and got a beep. So putting the probes between that R67 pad and the R68 pad beeps regardless of whether the card is Locked or Unlocked on my 50g. That is different from what Vtile tested on his 50g. I'm pretty sure that R67 pad is ground though because it connects to the foot (mount) of the SD card slot itself, nearest to where you insert the SD card. You can see all of that in my video, especially if you view it at full 1080p fullscreen. And yes, I probed both sides of R67 and my meter beeps both times when I touch the other probe to the SD card slot metal body.

I then probed the opposite side of R68, the side of that resistor which is furthest from the SD card slot, and found my Fluke meter beeped when I touched SD card pin-2, which is CMD (a data line).

After that I probed R66 (marked 102, which is a 1kΩ resistor), the side of the resistor facing opposite the SD card slot and traced it to R63, the side of R63 facing opposite of the SD card slot.

Still not sure what to think.

I wish a had a 50g schematic.