HD cable connected, power disconnected, but............

  • Thread starter Thread starter Bonnie
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Bonnie

What does a system see with power is disconnected from a HD?
I've got a problem with my new CD/DVD (secondary master) not
working when I install a secondary slave HD. Stranger still, with the
power disconnected from the secondary slave, the problem still exists.
I must disconnect the cable to the HD for the CD to work. In BIOS,
with the power disconnected, the HD is not seen, yet CD will not work
until I disconnect the HD cable.
So, what does the system see with the cable in place, and no
power?
Thanks, Bonnie
 
So, what does the system see with the cable in place, and
no


Your jumper setting is incorrect or

your cable is in wrong way around and/or defective or

your drive is buggy or

your secondary IDE is buggy on the mainboard or

what brand is it?

When you install the HD alone (take Optical drive off) does it work
with proper jumper settings?

Is the slave HD partition set as primary(active)?
 
What does a system see with power is disconnected from a HD?
I've got a problem with my new CD/DVD (secondary master) not
working when I install a secondary slave HD. Stranger still, with the
power disconnected from the secondary slave, the problem still exists.
I must disconnect the cable to the HD for the CD to work. In BIOS,
with the power disconnected, the HD is not seen, yet CD will not work
until I disconnect the HD cable.
So, what does the system see with the cable in place, and no
power?
Thanks, Bonnie

Not all hard drives will work as a slave to a CD/DVD drive.

Stephen
 
Try to swap the setting on CD drive and HD, in other words, make HD master.
I have encountered so many similar problems like yours, I just try all the
possible combination of settings, and more than 50% times, it worked.
 
?? Do you mean that you removed the power connector from the HD, leaving the
flat cable connected ?

If yes, that's normal the IDE chain doesn't work. The input & output
junctions of the disk electronic circuits, since not powered, are more or
less short circuits (say low impedances) vs the signals going through the
cable. Since they're common to the second device, it may function in
degraded conditions or it can fail.

If continuous use, it may result in an IDE controller or HD failure.
 
Really?? Cause damage? Makes sense, but I guess I'm really lucky, as
I've been using a (Different) machine rigged like that for YEARS!!
About 4 years ago I set up a machine with primary master HD, secondary
master CD, secondary slave HD. All set to auto in BIOS.
I have always run 2 different OS, one on each HD, by
switching power on and off between the two and rebooting. As I
recall, when I put this together, that was the only cable
configuration that worked properly.
Of course I don't actually remove the power cable, I
put a switch in the front panel to toggle the power on and off between
the 2 HDs.
Bonnie
*******************************************************
 
as long as the 12 and 5 volt sources are switched off, there should
not be damage to anything. Have done that in the past, for years on
some systems, with no ill affects.
 
Disconnecting the cable or turning Off the power is the same.
No power on the receiver (the hard disk), the input protection diodes of the
ICs connected to the IDE cable are forward biased by the output signals
delivered by the MoBo.
This approximately the configuration of the input gates connected to the IDE
cable. The diodes are internal to the ICs.

+-------->|----- + Vcc
|
(1) o---|----> to the input transistors of the gate
|
+--------|<----- Gnd

In normal use, the power is present, no current goes through the diodes
since the input signal (1) is slightly lower than Vcc.
Should the power supply fall to zero (switch turned off or cable
disconnected) the +Vcc and the Gnd are at the same voltage: 0V vs. the
ground line coming from the MoBo through the IDE still connected cable.
It is clear in that condition that the signal applied to (1) is
short-circuited to the +Vcc equal in fact to 0V.

Fortunately the logic circuits (the MoBo's ones in this example) have an
output impedance rather high. Added to the cable impedance and the PCB
tracks, it limits the current delivered by the MoBo bus driver outputs.
Nevertheless, they may be overloaded as well as the input protection diodes
which aren't intended for this use.

This may work or not, mainly depending on the MoBo features: cheap (without
too much sophisticated protections) or more expensive. This is also
temperature depending, linked to the load of the IDE bus, to the length of
the connections, of the IDE cable, to the frequency of the bus, ..., luck or
bad luck !

Normally a second disk connected to the same IDE cable should not work. It
happened to me once, forgetting to connect the power when I replaced my PSU.
The slave disk refused to be recognized.

The behaviour of such a configuration (yours) is exactly like a processor
die working at 80 °C and rated to 85°C. No margin, little overload, not
coping with the peaks. It may work for long before failing .

It's also exactly the same when you don't take a wrist strap when you change
memories or boards inside your computer.
You do the work lotta times. One day you may be charged with static
electricity. The accident happens, too late.

To be mentioned: the diodes I was speaking about are precisely the diodes
the IC manufacturers put in their layouts to protect the circuits against
the electrostatic discharges ! ! !

"" eppure gira ! ""

Hope this explanation will show you the importance of circuits loaded by
non-powered electronics.
 
Please read the answer I just made to Bonnie.
This is a false idea to believe that no power no risk.
The power IS applied to one side. This is THE problem !

Ask electronic engineers on the topic. You'll verify my assertion.
 
3 years - same HD's - no problems theory is theory 'practical
use' says it will not cause damage under the same conditions I
described. 2x WD's 80 gig 7200's 2000-01 vintage hardware. been switch
on and off 100's of times. Is it 100% fool proof? what is?
 
JAD said:
as long as the 12 and 5 volt sources are switched off, there should
not be damage to anything. Have done that in the past, for years on
some systems, with no ill affects.

Well, damamge is certainly possible. Some integrated circuits can be
damaged if the voltage level on pins exceeds the voltage to the power
supply pin - as could happen with disconnected power to the hard disk.
However, I'd hope the manufacturers would design everything in such a
way that a power cable becomming disconnected doesn't trash the whole unit.
 
As I said earlier, call me lucky I guess, having run my arrangement
for a few years, also, previously on another computer for a few years
with same arrangement.
I am putting together a new machine, and opted to
install a "TriosII Plus" arrangement which switches power AND cables.
We'll have to wait and see how that works outl.
Thanks alll, Bonnie
 
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