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http://forum.hddguru.com/viewtopic.php?f=15&t=9322		 Page 1 of 1
Author:  caluctra [ July 1st, 2008, 10:20 ]
Post subject:  question(s)
hello guys....

I was doing a T4 test to check the health of the heads, something like this:
Testing head 0...
DAC value = FFB9
Biasing with current 0025mA
DAC value = FFAE
Biasing with current 0050mA
DAC value = FFAD
Biasing with current 0075mA
DAC value = FC98
Biasing with current 0100mA
DAC value = FB8D
Biasing with current 0125mA
DAC value = FA82
Biasing with current 0150mA
DAC value = F977
Biasing with current 0175mA
DAC value = F86C
Biasing with current 0200mA
DAC value = FFB9

I would like to know
1. what does the DAC value stands for?
2. Is this a response from the HDD to the biasing current (could it also be an hex value that the microcontroller gives on the different current level? correct me if am wrong.
3. I graphed the HEX values of the different biasing current levels and it shows pretty linear behavior
3. I checked the hex parameters using a new HDD 160 GB brracuda 7200.7 and the max Hex value was less than 65000. Is this value siilar to all HDD or it changes with different capacities or model or something else...?

thanks in advance.
Pedro E.
Author:  caluctra [ July 1st, 2008, 17:28 ]
Post subject:  Re: question(s)
No one... :roll: ?
Author:  rchadwick [ July 1st, 2008, 17:36 ]
Post subject:  Re: question(s)
I don't understand. Are you trying to buy, or sell a drive?
Author:  caluctra [ July 1st, 2008, 20:44 ]
Post subject:  Re: question(s)
rchadwick wrote:
I don't understand. Are you trying to buy, or sell a drive?


Thanks for answering me AGAIN
I am trying to figure out what does DAC values mean or stand for, it they are a response from the HDD to the different biasing currents of the T4 test, and if the ideal value for them is 65000 or that value changes with diferent HDD capasity, model, etc..

The observation about the HEx value corresponding to each of the different levels of biasing current to each of the heads (25, 50, 75, 100, 125, 150 , 175 and 200)mA was pretty linear when I attempted to graph it; making possible to do some reverse engineering on this T4 test. "purely my observation" nothing more.

Regards
Pedro E.
Author:  Dmitry Postrigan [ July 18th, 2008, 3:17 ]
Post subject:  Re: question(s)
Please post to the proper forum.

Thanks
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