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Many telephone cables with RJ-11 plugs / jacks 

are wired in reverse. The CNT 10 L will show 

that a cable like this is crossed. A cable like this 

reverses the polarity of the telephone line. Most 

regular telephones made in the last 20 years are 

not polarity sensitive. So, even though the cable 

is wired in reverse (crossed), it may work OK.
Early touch-tone telephones and answering 

machines were polarity sensitive. lf connected in 

reverse polarity, the touch-tone phone may not 

dial out (no touch), and the answering machine 

may not answering machine may not answer 

when the line rings.

7 .6.4 The CNT 10 L says my RJ-11 phone 

cable is good, but my phone doesn‘t work.

First, make sure the telephone line is active.
The “good“ cable may result in a reversed line. 

The line is not actually being reversed in the 

good cable it‘s been reversed somewhere else 

along the wire. Either the reversed cable can be 

located and corrected, or, an oftenused simpler 

approach is to replace the good cable with a 

reversed cable, making the polarity come out 

correctly. It is also worth knowing that some 

female/female couplers reverse the polarity of 

the phone line.
Analog telephones will usually work, regardless 

of line polarity. Digital phones are often polarity 

sensitive, and may not work with reversed line 

polarity.

CNT10L_Manual_en.indd   12

25.06.2019   14:19:13

Summary of Contents for CNT 10 L

Page 1: ...Network Cable Tester Manual CNT 10 L CNT10L_Manual_en indd 1 25 06 2019 14 19 12...

Page 2: ...es The 4 in 1 Cable Tester tests 4 common LAN and Computer cables It tests installed cables or patch cords with RJ 45 RJ 11 USB and BNC connectors It is intended to test cables with straight through c...

Page 3: ...first disconnecting it from all external circuitry Failure to observe this precaution may result in damage to the tester or injury to the user 2 6 Repairs and maintenance must only be carried out by q...

Page 4: ...sing 2 14 Do not modify this tester Changing the design may make the tester unsafe and may result in injury to the user 2 15 Do not use this tester if it has undergone long term storage under unfavora...

Page 5: ...ded STP or unshielded UTP LAN cables 3 12 Test shields in USB cables 4 1 Cables Tested UTP and STP LAN cables Terminated in RJ 45 male connectors ElA TIA 568 RJ 11 cables with male connectors 2 to 6 c...

Page 6: ...Contents 6 5 1 Test Button 5 2 Main Display 5 3 RJ 45 Jack 5 4 RJ 11 Jack 5 6 USB Jack 5 7 BNC Jack CNT10L_Manual_en indd 6 25 06 2019 14 19 13...

Page 7: ...The Remote is often attached to the Main unit when storing when transporting or when patch cables are being tested The Remote is removed from the Main unit when an installed in wall ceiling etc cable...

Page 8: ...with light and the Beeper will sound once 6 6 4 Connected LED Lo Hi Beep Numbered LEDs If the Connected LED lights and the Beeper emits a LoHi beep examine the numbered LEDs i e LEDs numbered 1 to 8 a...

Page 9: ...n crossed This seldom affects the performance of Standard analog telephone lines POTS Digital telephone lines and old touch tone phones may be polarity sensitive so a cros sed cable may prevent them f...

Page 10: ...p or put in ser vice and it tests as Open or Crossed the RJ connec tors have probably been installed incorrectly Shorts very seldom occur as the result of a badly crimped RJ connector so the user shou...

Page 11: ...e cable will test ok But when the cable is tried on the LAN it does not work This is because the Iack of the proper pairing causes exces sive cross talk in the cable Preventing the LAN from working Th...

Page 12: ...e line rings 7 6 4 The CNT 10 L says my RJ 11 phone cable is good but my phone doesn t work First make sure the telephone line is active The good cable may result in a reversed line The line is not ac...

Page 13: ...justments Calibration is not required To clean the outside of the tester use a cloth dampened with a mild detergent solution Do not use any abrasive cleansers or chemical solvents that may damage the...

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