Mac does not see my Compact Flash

danpak

All of a sudden, my iMac does not "see" my compact flash. First I thought it was the card reader. Bought a new one. Still not working. The usb port is working fine - my other usb devices are fine. I tried a SD card on a different reader. Strangely, this does not work either. It almost seems that my iMac is discriminating memory cards - sd and compact flash. A usb thumb drive is being recognized too. This has me baffled...:scratch

Did this happened to anyone???

danpak

Now it works... confused
Don't know what happened. Now it works. Still can't figure out why
Just wanted to update you...

darkdragon

i don't know if this is related to the same issue you are seeing, but I had something similar happen on my iMac.

Turned out after many tests that the issue was with the power draw on my USB hub. My new card reader wanted too much power and I ended up having to plug it directly into the imac usb.

cmason

Found a similar thing: when I have recognition probs on USB devices, plugging into the port on the back of the iMac usually clears em up. using a hub, or even the port on the keyboard can be hit or miss.

BradfordBenn

I deal with USB weirdness often at work, the first question is, does the hub have an external power supply? Well plug it in, and viola it works. It is one of the reasons that Apple even says that when plugging in an iPod to an iMac not to use the keyboard. Too much power drop.

danpak

Thanks for all your responses...
However, I only use powered usb ports. So.. this couldn't have been it. I will share it with you when/if I figure it out.

Thanks again.

darkdragon

danpak wrote:

However, I only use powered usb ports. So.. this couldn't have been it. I will share it with you when/if I figure it out.

Thanks again.

My USB port is also powered, that is why it was so strange when I had the same issue. I still don't know what happend really

BradfordBenn

I did a little more digging. This is what I found out, and it is a little sketchy and I probably won't explain it very well. On some operating systems, I am not sure if this applies to Mac or not, once a card is ejected/removed after being used that port will no longer acknowledge the card being reinserted until after the OS is restarted/logged out and logged back it. The reason that I could determine is that the OS has decided that the device was ejected and it ignores it. In theory just putting it into another USB port with a different identifier would make it work.

The info I got was just enough to make sense but basically what happens is that the OS decided to ignore the ID combination (port & device) as it was ejected/removed. It is a trick to speed up the bus.

CatOne

BradfordBenn wrote:

I did a little more digging. This is what I found out, and it is a little sketchy and I probably won't explain it very well. On some operating systems, I am not sure if this applies to Mac or not, once a card is ejected/removed after being used that port will no longer acknowledge the card being reinserted until after the OS is restarted/logged out and logged back it. The reason that I could determine is that the OS has decided that the device was ejected and it ignores it. In theory just putting it into another USB port with a different identifier would make it work.

The info I got was just enough to make sense but basically what happens is that the OS decided to ignore the ID combination (port & device) as it was ejected/removed. It is a trick to speed up the bus.

Not typical, but if the volume is removed "improperly" (i.e. without being ejected first) this can happen.