TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas

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Page 36 The “low” and “release” potentiometers are provided for the adjustment of the current through the selector for low and release tests. Lever type keys for applying the various test conditions. A centre zero micro-ammeter, with shunts for measuring test currents and observing the impulse ratio. A mounting with spring contacts which automatically connects the selector in the test circuit. Two terminals L1 and L2 for connecting the set to an outside line, and three terminals K1, K2 and K3 for connection to an external selector key, key case or external source of impulsing. When a key case is mounted in this manner it must be entirely disconnected from its associated selector apparatus case. The apparatus is mounted on a removable wooden panel in a wooden case with cover and carrying handle. Inside the cover is pasted a schematic (LP. 15500) of the test circuit, together with step-by-step instructions for operating the set, similar to the following :- Operating Instructions Connect a battery of 240 ± 8 V D.C. to the terminals so marked, and connect another battery of 10 ± 1 V D.C. to its marked terminals. Insert the selector key to be tested under the five spring terminals at the back of the selector tray, and operate the main switch. To Adjust the Test Set The Selector Key provided is a general call key, and will step any selector to its ringing position. The speed and ratio of this selector key should be checked in the following way :- Speed. — Operate the selector key and make sure that the time taken for the mechanism to run back, from start to finish, is between 7½ and 8 seconds. If the timing is not correct the governor springs of the key must be adjusted either inwards or outwards to obtain more or less speed respectively. Ratio.—Throw the Ratio Key (KIR on diagram). Again operate the selector key, and observe that when impulses are being transmitted the needle of the meter oscillates equally about the zero mark. If this is not so, variations can be eliminated by turning with a suitable screwdriver the head of the ratio rheostat in the centre of the panel (YJ on diagram). When this adjustment has been made restore the ratio key. Test Current.— Adjust the test currents through the selector by proceeding as follows :- Throw the "Low" key (KL on diagram) and hold the "Meter" key (KM on diagram) operated, then adjust the knob of the rheostat marked "low" till the micro-ammeter reads 125. The meter multiplier in this case is
4001-B Selector Test Set, Schematic. Fig. 12. Page 37
Page 2 and 3: TRAFFIC CONTROL TELEPHONE SYSTEMS C
Page 4 and 5: CONTENTS Part Title Page 1 Key Syst
Page 6 and 7: swing of the meter needle either si
Page 8 and 9: One No. 4002-B Selector Key Case (c
Page 11 and 12: wires. This change of polarity is t
Page 13 and 14: Case), K2 terminal (Time Sending Se
Page 15 and 16: Where satisfactory operation cannot
Page 17 and 18: one is available (if not, with an o
Page 19 and 20: PART 2 4001-A SELECTOR KEY Selector
Page 21 and 22: The keys are easily removed from th
Page 23 and 24: Letter. Name. S.T.C. Code. A Impuls
Page 25 and 26: 4. When the key is normal the tip o
Page 27 and 28: the time terminal. During selective
Page 29 and 30: Cycle of Events on Receiving a Code
Page 31 and 32: Mechanical Requirements To assist i
Page 33 and 34: (b) The contact spring (Z) in the n
Page 35 and 36: Letter Name 4301-A 4304-A 4305-B A
Page 37: General PART 4 4001-B SELECTOR TEST
Page 41 and 42: General PART 5 DIAL SYSTEM, SELECTI
Page 43 and 44: The speak key also connects the con
Page 45 and 46: normal, Relay IR is held operated a
Page 47 and 48: here that from SC bank contacts 29
Page 49 and 50: from Line switch SC banks 1 and 2 a
Page 51 and 52: Line Test Set . . . . . . Designed
Page 53 and 54: Line Voltage Curves Fig. 14. The op
Page 55 and 56: General PART 7 LINE TEST SET-LU.310
Page 57 and 58: Operating Instructions 1. Voltage M
Page 59 and 60: the particular line to the earthed
Page 61 and 62: Operate CVK, note meter reading on
Page 63 and 64: 10. Impulse Ratio Check on Selectiv
Page 65 and 66: 12. Telephone Communication. (See F
Page 67 and 68: Page 65
Page 69 and 70: Armature Travel Armature travel is
Page 71 and 72: Contact Sequence The standard conta
Page 73 and 74: chloride or trichlorethylene. The t
Page 75 and 76: PART 9 ADJUSTMENT AND MAINTENANCE D
Page 77 and 78: 9. Armature Restoring Springs:— T
Page 79 and 80: Oil dag should be applied as above
Page 81 and 82: 3. Pawl Spring Tension 3.1 With the
Page 83 and 84: 8.6 The wipers shall exert a pressu
Page 85 and 86: 2.2 The wipers shall rotate smoothl
Page 87: Registered Office: CONNAUGHT HOUSE

TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas

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