Chunky lump on monitor cable

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dotnw

What is that chunky lump thing on a monitor cable?

For monitor extension cables, does it matter which end the lump goes -
either at the PC connection end, or at the connection point where it
links up with the main monitor cable?

Thanks, regards, dnw.
 
What is that chunky lump thing on a monitor cable?
For monitor extension cables, does it matter which end the lump goes -
either at the PC connection end, or at the connection point where it
links up with the main monitor cable?
Click to expand...

My educated guess would be that it's some sort of protected splice where the
connector is added to the cable.

If it's an extension cable, it will have one male connector at one end and
one female connector at the other end. Generally, the male connector from
the monitor cable (or extension cable) fits in the female connector on the
VGA. If it's a male-male DVI connection, the position of the lump/splice
doesn't matter.

- f_f
 
What is that chunky lump thing on a monitor cable?

For monitor extension cables, does it matter which end the lump goes -
either at the PC connection end, or at the connection point where it
links up with the main monitor cable?

Thanks, regards, dnw.
Click to expand...

Actually this was covered here a short while ago. The "lump" is a ferrite
core
intended to act as a low pass filter for common mode currents that might
cause the system to not meet various agency limits for radiated and
conducted
high frequency (radio) emissions. You may find similar "lumps" on various
other
PC system interconnections, most likely on USB cables, for example.
When you add an extension cable you are doing two things that are
generally
recommended against:
1. Compromising the EMI design of the system, which may cause
interference
with radio types of receivers, and could end up causing you to have
to disable
the offending system. In the worse case an enforcement agency may
actually
seize the equipment, but I do not know of any specific cases where
that has
ever happened.
2. Compromising the integrity of the signal path, which is quite likely
to result
in ghosting or other artifacts related to impedance discontinuities
and
signal path length. This does depend a lot on the original integrity
and on
how well the impedance of the extension cable matches the impedance
of
the original system transmission line.

As to which end it should go, typically there is no choice when it comes
to
extension cables. If your original configuration has the core at the display
end,
it is recommended to leave it at that end, and vice-versa. But in most cases
any
alteration of the designed configuration will exacerbate the first risk
mentioned
above, so the core location is pretty much moot in that instance.

Regards,
NGA
 
These devices are useful for trouble shooting, they protect PC equipment
from monitor RF and you can get these filters that clamp on to cables (old
trackpoint keyboards sometimes need these)
 
By using a monitor extension cable, I now have 2 lumps between my
monitor and PC. Would it be better if I got rid of the extension cable
and bought a longer monitor replacement cable, thus reducing the number
of lumps in my cable back down to 1?

(I can't see any problems with my current set-up - image quality wise.)

Thanks, regards, dnw.
 
By using a monitor extension cable, I now have 2 lumps between my
monitor and PC. Would it be better if I got rid of the extension cable
and bought a longer monitor replacement cable, thus reducing the number
of lumps in my cable back down to 1?

(I can't see any problems with my current set-up - image quality wise.)

Thanks, regards, dnw.
Click to expand...
Definitely better from the standpoint of reducing the number of
possible impedance discontinuities along the line (where the connectors
are) - not important at all from the standpoint of reducing the lump factor,
as they tend to operate at frequencies much higher than the pixel rates.
The lumps (cores) should not be contributing any negative aspects to image
quality.
This *does* assume that what you can get in a longer cable will have
good enough impedance characteristics to avoid or at least minimalize
possible image degradation. Try to look for one that has a low a
resistance value as possible for the "co-ax conductor" between the two
ends, as that factor will tend to decrease the signal amplitude at your
monitor end, likely resulting in lower luiminance output (assuming you
are using analog "VGA", not DVI). If you can find an "active" type of
extension (AKA KVM) you may be happier with the performance, but
the cost will be higher, typically. But that way you can have the imput
devices Kbd & Mouse) nearer the display (V).
It still does not necessarily mitigate the other factors I mentioned to
use a single long cable, compared to two (joined) shorter ones. As far
as KVM operation, I have no personal experience, but at least some of
them are active types, and user satisfaction reports are generally
favorable.

Regards,
NGA
 
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