HP TM 11-6625-2779-14&P Section, Operating Instructions, Controls Connectors Indicators, Battery

Section III	Model 3555B
	SECTION III
	OPERATING INSTRUCTIONS

3-1. INTRODUCTION.

3-2. The Model 3555B Transmission and Noise Measuring Set is an extremely versatile transmission and noise measuring set which satisfies many of the requirements in testing telecommunications equipment. The 3555B features a choice of 900 or 600 ohms bridging or terminated for voice frequencies and 600, 135 or 75 ohms bridging or terminate for carrier frequencies. Noise- to-ground and noise Metallic may be measured with 3kHz Flat, C-Message or 1 5kHz Flat weighting. A HOLD function permits seizing the line while measurements are being made at voice and program frequencies. The set is portable and operates from the internal battery, office battery or ac power source.

3-3. This section of the manual contains all the information necessary in the operation of the 3555B along with a description of all controls, connectors and indicators.

3-4. CONTROLS,	CONNECTORS	AND
INDICATORS.

3-5. Figure 3-1,3-2and Table 3-1illustrate and describe the function of all front and side panel controls, indicators and connectors.

3-6. OPERATION.

3-7. To operate the Model 3555B, refer to figure 3-1and perform the following steps:

a.Before connecting the 3555B to an ac power source, insure that the 115/230 volt switch is positioned to indicate the line voltage to be used. Some earlier instruments did not have the 115/230 volt selector switch. To change these instruments, jumper wires must be changed on the power transformer. Refer to Appendix C for a wiring diagram of the two configurations.

b.If the set is to be operated from the internal battery or from an external office battery, place the AC/BAT switch (located on the side of the set) to the BAT position, using a small pointed object; if the set is to be operated from the ac line, place the AC/BAT switch to the AC position. For operation from a 24 or 48V office battery, connect a patch cord with a Western Electric 310 plug to the battery jack on the side of the case and then connect the cord to the office battery on the test board or bay. Inserting the plug disconnects the internal battery. The office battery is

arranged for -48V or -24V ±2V with the negative terminal of the battery connected to the tip and the ground terminal connected to the sleeve. Current consumption by the 3555B is approximately 15mA.

WARNING

DURING BATTERY OPERATION, THE "G" BINDING POST MUST BE CONNECTED TO EARTH GROUND.

CAUTION

THE CORD MUST BE CONNECTED TO

THE MEASURING SET BATTERY

JACK FIRST AND THEN PLUGGED

INTO THE BATTERY SUPPLY TO

AVOID SHORTING THE OFFICE

BATTERY TO GROUND.

c.Turn the POWER switch to ON and depress the DIAL/BAT pushbutton on the FUNCTION switch. The meter pointer should indicate in the BAT GOOD area indicating that the battery condition is good if the set is being operated from the internal battery. The meter will also monitor the ac supply voltage or the external office battery voltage, providing an indication of low voltage should it exist. The voltage should cause meter deflection above the lower end of the green BAT GOOD area for proper set operation.

3-8. BATTERY.

3-9. The internal dry cell battery has a voltage range between 45 volts when new to 24 volts at cut-off which is the end of useful life. The cut-off voltage corresponds to the left end of the green BAT GOOD area on the meter. The condition of the battery and the approximate time to cut-off can be estimated by observing the position of the meter pointer in the BAT GOOD area.

3-10. The internal battery is of the carbon-zinc type with its attendant limitations due to temperature. The service obtained from carbon-zinc batteries depends on factors such as current drain, discharge temperature, discharge time and storage prior to use. The battery supplied with the 3555B should provide in excess of 180 hours of operation based on a 4 hours/day duty cycle at 77° F (25° C). At other temperatures this time will change. At temperatures above 131° F (55° C) the batteries may fail suddenly while at temperatures below 40° F (-20° C), the service life will be short.

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