https://www.thomann.de/fi/millenium_mct20.htm

The MR-PRO features a cable test function that quickly detects
bad or wrongly terminated XLR cables.

The cable test function detects the 1:1 connection of XLR cables
by adding two different resistances at the cable end (1 kOhm and
2 kOhm resistance). In case the impedance measurement finds
the expected resistance values then the MR-PRO indicates “OK”
for a proper 1:1 connection

http://www.nti-audio.com
A p p l i c At i o n n ot e
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Sample Test Results displayed on the MR-PRO Screen
The tested cable is defective, the pins
2 and 3 are crossed. Other error indi-
cations may appear depending on the
cables fault.
The tested cable is OK.
2. Cable test for pin1 detection
Imagine you assemble a standard 3-pin XLR cable, but acciden-
tally solder the cable shield to pin 2 and the hot wire to pin 1 on
both sides. This cable is commonly analyzed by all cable testers as
“OK”, as all pins are 1:1 connected, but the MR-PRO detects such
assembly problems.
How can a wrongly connected shield be detected?
A good XLR cable is a nearly perfect balanced device. For most
audio cables the capacities between pin2 – pin1 and pin3 – pin1
will differ less than 5%. Differences higher than 10% are pos-
sible indications of a shielding fault. Differences exceeding 25%
confirm an unbalanced cable, caused by a wrongly assembled
shield