I'll try to make this as concise as possible.

I replaced the HD in my iMac G5 with WD2500KS. Worked fine until the other day when it would no longer boot. I've had similar problems in the past with this computer so I immediatly rebooted in target disk mode to save the most important data on the drive (like my new baby's photos, of course) before I reinstall OSX. This has worked very nicely in the past and have not had any problems getting data off the drive this way. But not this time. The HDD image failed to mount on my Macbook's desktop. The drive does show up in the disk utility but only shows the generic hardware name and not the formatted volume name. I tried using data rescue II but it won't work properly and I'm waiting on tech support from them. Also, once when trying to mount the drive when I checked Disk Utility to make sure it was connected and it showed that it was a 7.5 GB drive when it is a 250GB (usually comes up as 232.9). I was told this could have something to do with the firmware or the control board on the drive itself. Can anyone give me any input on how I can get this thing working again so I can recover some of my data???

Just talked to tech support and they told me that if I could update the firmware we would be in business. Any ideas on how I can get that? I've called the manuf. but they were not helpful at all. Maybe I could replace the controller board? Don't know where to find one of those either...

I think you have a Firmware Error in youre Hard Drive. if just Detect 7.5 GB and youre Disk its from 250 GB, i think you have a Firmware error.

Hi,
Check this post for information on what you need to match in order to successfully replace the PCB on your HDD: hard-disk-drives-repair-and-data-recovery-f1/information-on-compatible-pcbs-for-all-brands-t7646.html
Good luck!