Subscriber Loop Analyzers


© Brooke Clarke 2015

Background
Description
    Dynatel 745
    Operation
    Battery
    Photos
    Dynatel 965
    Battery
    Photos
Related
Links

Background 

In the 1950s telephone installers (all working for AT&T) used the KS8455L2 Line Loop Tester aka: Kick Set for testing the phone line while at a subscriber's premiss.  More modern test sets, like the Tempo Sidekick could make more sophisticated tests, but they required more operator skill.  Dynatel came out with a series of subscriber loop analyzers that would automatically run a series of tests on the loop thus lowering the required skill level required of the telephone technician.
Some of these have been showing up on eBay ("Subscriber Loop Analyzer") for very low prices (less than the shipping).  I suspect this is because the internal battery has quit taking a charge and needs to be replaced.  So it's a gamble buying a Dynatel 745 and Dynatel 965 subscriber loop analyzers in the hope that I can come up with a battery replacement.

Description

Dynatel 745M Subscriber Line Tester (SLT)

At power up the display shows Dynatel 745M, Battery OK (after installing a new battery).

This test set came with test leads and a 2-wire (Red & Black) 1/4" phone plug.  I expect the stock test leads would have included a 3-wire (stereo) 1/4" phone plug and Red, Black & Green test wires.  How important is the missing green (ground) test wire?  Contact me.

Operation

Pressing (Yellow) START/reset powers up the test set.  Pressing (Blue) # (when it's not shown on the LCD as an option) turns off the set.  This disagrees with the manual that says you need to press # then START to power off.  Pressing and holding down START/reset will power down the test set.

Self Test

Once the opening screen is displayed the pressing (Blue) Self Test starts a menu process where pressing (Blue) * selects the test displayed on the top line of the LCD and pressing (Blue) # Other Self-test moves to the next test option.  Note that these are not the actual tests but rather calibration or checking of the test set function.

The test options are in order:

Charge Battery

This requires connecting the Red and Black test leads to a source of 12 to 15 VDC.  Then the menu sequence:
START/reset, SelfTest, # (Charge Battery), turn SLT upside down for 5 seconds and then right side up.
Leave overnight to charge battery.

After 5 minutes (starting with a charged battery) the SLT makes the power off noise and the LCD turns off.  But the power supply is showing 178 mA current draw at 12 Volts.  It's not clear if that's going to the battery or just a voltage regulator in the SLT.

If the power supply is disconnected then reconnected the current is zero.  So maybe there's a sticky relay that should have turned off?

Ohms Test

Prompts you to short all three (or 2) test leads then does a zero calibration.

Opens Test

Prompts you to remove the 1/4" plug and test leads then does an open calibration.

Dialing Test

Requires connection to an active telephone line to run the test.

Display

By pressing * or # the LCD contrast can be changed for your viewing angle.  If the screen goes blank just press the other button (# or *).

Battery

Power sonic PS-610, 6V, 1.0 Amp Hr., 2" x 1.625" x 2.017" hi + 0.187" terminals.  When put on a bench power supply (Agilent E3617A) at 65 Volts it initially did not take any current.  I'll let it sit overnight with the current limited to 10 mA to see if it's totally dead.  A new PS-610 is available on the internet.
After a couple of hours the current is up to about 1 mA.  Got new PS-610 battery.

There's a problem when installing battery in that one of the bosses on the bottom of the case interferes with the battery cable end preventing the battery from completely seating.  I bent the battery terminal to minimize the problem, but not eliminate it.

After reconnecting everything pressing START/reset causes the LCD to come on and an opening tone to play.

In the lower left of the instructions (Fig 3 below).  This involves connecting the red and black test leads to a car battery (12 to 15 VDC source), turning the tester upside down for 5 seconds (see mercury switch on PCB #5 (Fig 10 below) and then righting the tester while battery is on charger.

Note the special battery charging connector next to the 1/4" phone jack is wired to the Red and Black wires on the phone jack, so there's really no need to use it.  Just connect the red and black test leads to a 12 to 15 VDC source and go through the menu sequence for battery charging.

745 Photos

Fig 1 Front
Dynatel
                      745 Subscriber Loop Analyzer
Fig 2 Back & 2-wire Test Leads
Should be 3-wire (Red, Blk & Grn)?
Dynatel
                      745 Subscriber Loop Analyzer
Fig 3 Instructions & Front Panel
Dynatel
                      745 Subscriber Loop Analyzer
Fig 4 Inside box
Use 2mm hex wrench to remove a dozen screws.
Dynatel
                      745 Subscriber Loop Analyzer
Fig 5 Battery at bottom undere everything else!
Dynatel
                      745 Subscriber Loop Analyzer
Fig 6 PCB #2
Dynatel
                      745 Subscriber Loop Analyzer
Fig 7 PCB #1
Dynatel
                      745 Subscriber Loop Analyzer
Fig 8 PCB #4
Dynatel
                      745 Subscriber Loop Analyzer
Fig 9 PDB #3
Dynatel
                      745 Subscriber Loop Analyzer
Fig 10 PCB #5
Dynatel
                      745 Subscriber Loop Analyzer



Dynatel 965

After replacing the 5 dead Alkaline "C" cells the unit powers up and will do the self calibration, but then "access" is selected (*) the LCD shows:
General Access
Enter Password
What is it? Let me know

Battery

By unscrewing the 6 captive screws on the bottom panel the 5 "C' cells can be replaced.
The start-up menu allows selecting either Alkaline or Ni-Cad cells.

Photos

Fig 21 Dynatel 965 Yellow Lunch Box Subscriber Loop Analyzer
Dynatel
                      965 Yellow Lunch Box Subscriber Loop Analyzer
Fig 22 Bottom has compartments.
Dynatel
                      965 Yellow Lunch Box Subscriber Loop Analyzer
Fig 23 Cable Self Test Circuit
p/n: 0002-7535-001-D   3M
aka: Far End Device (FED)
Dynatel
                      965 Yellow Lunch Box Subscriber Loop Analyzer
Fig 24 Battery Compartment
5 Alkaline "C" cells (all tested dead)
Dynatel
                      965 Yellow Lunch Box Subscriber Loop Analyzer



 


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Links

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Page Created 25 May 2015