I've run tests with a few different hard disks. I have observed operation and measured power consumption and the voltage regulation of the 5V and 12V supplies. Voltages were measured using a Fluke 77 Multimeter at the power supply board connector from the yellow (12V) or red (5V) wire to the adjacent black wire. Power is measured using the Brand Electronics 20-1850 Power Meter
. Here are my results:Included hard disk (250 GB 3.5"):
I did not remove it to check the part number.
5V: 5.15V 12V: 12.45V Power (Off): 21W Power (On): 23W
No problems with operation noted so far.Western Digital WD10EACS-00ZJB0 (1 TB 3.5"):
This drive was pulled directly from a RAID 1 array and inserted into the DTVPal DVR as is.
5V: 5.15V 12V: 12.35V Power (Off): 19W Power (On): 21W
This drive does NOT work with the DTVPal DVR. Unit reported problems with the hard drive. I attempted to format the drive, but the unit simply shut down and then reported that the drive was not working when it restarted.Seagate ST9500325AS (500 GB 2.5"):
This drive was pulled from an external USB enclosure. It was formatted NTFS with compression turned on.
5V: 5.15V 12V: 13.95V Power (Off): 17W Power (On): 19W
This drive WORKED in the DTVPal DVR. However, the picture frequently broke up when this drive was being used. I suspect with the 12V output of the power supply unloaded (and hence unregulated) the operating mode of the switching power supply may have changed, leading to much worse EMI. Another possibility is that the 5V supply may not have become unstable (or possibly contained much more ripple) when the 12V supply was unloaded. The bottom line is that the unit became quite unusable even though the drive worked properly. Interestingly, even though information was recorded onto this drive, it was not obvious this was the case when it was later read using a Windows computer. No new data was found and no former data was obviously lost. (I won't trust the data on the disk, however.)Western Digital WD2500BEVS-60UST0 (250GB 2.5")
This drive was previously the internal drive within a Windows Vista Ultimate tablet computer. It was working fine when removed.
5V: 5.15V 12V: 13.99V Power (Off): 17W Power (On): 19W
This drive does NOT work with the DTVPal DVR. Unit reported problems with the hard drive. I attempted to format the drive, but the unit simply shut down and then reported that the drive was not working when it restarted.Toshiba MK1246GSX (120GB 2.5")
This drive was previously the internal drive in an Ubuntu laptop. It was formatted with several partitions including file formats such as ext3 and swap.
5V: 5.15V 12V: 14.00V Power (Off): 16W Power (On): 18W
This drive WORKED in the DTVPal DVR. I was in a hurry, so I did not observe whether the same tuner problems I saw with the Seagate drive existed. I suspect they did.Conclusions:
1) While some 2.5" drives appear to work in the DTVPal DVR, it appears the the power supply does not like having its 12V output unloaded. Somehow this results in frequent breakups in the picture.
2) The 2.5" drives save approximately 4W over the stock drive.
3) The only 3.5" drive I have on hand does not seem to work in this unit.
4) The low-power 1 TB WD drive saved only about 2W of power in the unit, which is less than I had predicted based on specifications. While the added space would have been nice had it worked, the overall power savings is less than 10%.Thoughts:
5) I'm wondering what factors determine whether a drive can be used or not. Is it the characteristics of the drive or the type of partitioning pre-existing or something else?
6) I'll probably stick with what's in there for now, as I'm new to the DVR world and I don't know if I'll use more than 250 GB or not.
I'll keep the unit open for a couple of days while I'm still on vacation. If anyone would like me to conduct further tests, please let me know.