Parkend Exchange Line Testing Arrangements

We have a tester AT5422 but no cords with which to connect it to our test jacks or fuse mounting. The answer is to use a test selector to gain access to exchange lines. We have also had to develop a small console with which to control the test selector. Arrangements for testing junction circuits etc still have to be designed.

Test Selector

Parkend Test Selector Circuit

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This test selector has been constructed using simple circuit elements from a final selector stepping circuit. The test selector merely positions the wipers onto the required exchange line multiple position and extends the -,+ and H wires to a test selector control console.

Test Access Control Circuit

Parkend Test Access Control Circuit

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This equipment positions the test selector onto a wanted exchange line multiple position with a dial key and dial. The P (or H) wire condition can be examined by operating the "Check P wire" key. A busy customer will light the P wire lamp. To remove the line circuit bridging conditions the "Busy P wire" key is operated to earth the P wire. The line can be extended to the At5422 by operating the "Conn Line" key.

Tester AT5422

Parkend AT5422 Circuit

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The AT5422 is a standard model, however our copy of the circuit diagram is not very clear and reproduces badly.

Tester AT5422 Power Unit

Parkend Tester AT5422 Power Unit

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The tester normally requires a pair of batteries for line testing purposes, but this version of the AT5422 has arrived with a mains unit to provide the floating voltages required.


Page provided by John Bathgate

This page was last updated on
2nd July 2012