THE PHONE REPAIR COMPANY

The Phone Repair Company

High Open - Electrolyze

• Also know as a High Joint
• The high open is an inline resister on the Tip side of the cable pair.
• It will show as the Tip side being electrically longer then the ring side. ( This is if the pair was used for POTS service )
• A high open will cause trouble long before it will make a noise on the cable pair.

To Test for a High Open

1. On the office end of the cable pair hook the tip and ring up to a good tested ground (<25 Ohms) if there no test for a good ground, then hook up to a power neutral.
2. At the field end of the cable pair using an Ohm meter with a digital read out.
3. On the field end, test the ground with the ground resistance test or use a power neutral hook up.
4. Test the pair Tip to ground Ring to ground, and Tip to ring using the Ohms. Record each reading.
5. The Tip Ohms and the Ring Reading should be the same.
6. Half the amount of the Tip to Ring Ohms reading.
7. If there is a difference of 3 Ohms or more between the Tip and Ring side to ground there is a high open on the pair. ( Long loops of 700 Ohms or more should be cut in half, and the test done twice)

The presence of a high open of 3 Ohms will cause Circuit xDSL, dsl, ext, ext to drop at times, to produce errors and a number of outer tricks.

To Find a High Open

1. To cut a cable rough in half and narrow down the area the trouble is in, works very well. Use the test equipment to help you. ( if you see the high open 500’ away with the TDR you do not have to go 1 mile to the haft way point) I would go 500.
2. The TDR is the best test equipment to use for a high open.
3. If you Have an old 965 RST Dynatel (lunch box) use the special mode in the open test. It will help you find the high open.

Source: World English Dictionary

Contact Jake if you have any questions.

“There is no problem in any twisted copper cable that cannot be located in a timely manner and a solution found for the repair of such problem” - John “Jake “Jacobsen