M7880H

MFG MFG PART NUMBER

J1 Connector Hood, 9 Pin TEEE TCE 9

J2 Connector Hood, 15 Pin " TCE 15 (supplied upon request)

J6 Connector Hood, 25 Pin " TCE 25 (supplied upon request)

SPKR Speaker Screen WBS B9769

SA14-270G Fish Paper " C7880-014 SA14-271 " " C7880-015 SA14-246H " " C7880-064

P/S 1 Power Supply Housing " C7880-42 Terminal Useco 4826-1-05-16

Grommet Ontario Rubber 225 Screw, Metric, Slotted HD " M3X5

WBS recommends the use of replacement parts made by the specified manufacturers for continued optimum equipment performance. The M7880H is a simplified sixteen key communications terminal. Providing simplified operational characteristics where the full capability of the M7880D terminal is not required.

This terminal is self powered, containing the required audio amplifiers and microprocessor based control system, to operate all control and communications paths to and from the central switching matrix. It is inclusive of an integral dynamic gooseneck microphone, loudspeaker and sixteen talk select keyswitches.

The control, assignment and programming of keyswitch data is transferred to and from the central matrix on a balanced serial RS422 data line. The audio input and output of the M7880H are balanced 600 ohm lines operating at +8 or +4 dBu. The above three balanced lines allow full communications between the terminal and the central matrix.

The M7880H has sixteen programmable talk keyswitch functions, each consisting of a momentary and a lock pushbutton. The pushbutton pair replicates the traditional telephone lever key, with its centre off position, an up lock and a down momentary position. The lock key position is cancelled any time the momentary function is selected.

Associated with the sixteenth talk keyswitch is a Call Assign pushbutton. This keyswitch is reserved for answering unassigned calls to the communications station (Call Waiting). No assignment is accepted by this keyswitch from the central assignment computer.

Optionally the lock keyswitch tally may be programmed as an identifying calling tally.

Audio from the integral dynamic or the external headset microphone is amplified to a nominal line level of +8/+4 dBu. A front panel sensitivity control (SENS) is available to make level adjustments for variations in operating techniques. Input levels over a sensitivity range of 30 dB are accommodated.

An auto levelling type limiter stabilizes the audio output from the microphone preamplifier, assuring constant system levels over a large range of voice variations. Two level indicators, located above the sensitivity control are provided. One labelled NORM (normal), it flashes when the preamplifier output is a nominal +8/+4 VU. The other labelled OVLD (overload) flashes when the limiting action becomes excessive (greater than 20 dB).

A third indicator, labelled XMIT illuminates when an assigned talk keyswitch is operated, indicating audio is being transmitted from the communications terminal. An external footswitch control may be looped in series with the lock talk keyswitch control functions.

A power amplifier boosts the incoming audio signal from the matrix and drives an integral speaker. A front panel level control is provided for the speaker output. The amplifier is capable of delivering up to 3 watts into an 8 ohm load.

The terminal is powered from an integral modular power supply, operating from 115/230 Volts AC 50/60 Hz.

The M7880H terminal is housed in a 3-1/2 inch high (2RU) aluminum chassis, designed for standard nineteen inch rack mounting. Its shallow depth (less than 10 inches) allows the terminal to be easily mounted in typical television production desk operating areas. It is constructed on a modular philosophy, with all active circuit modules interconnected via ribbon cables and chassis type connectors. All modules are easily removed for any required service. Enhancements:

Enhancements are incorporated from time to time, to address or improve product operational characteristics. Usually these enhancements are compatible with existing systems. It may be necessary to obtain an overall systems software update package to make use of incorporated changes. Front Panel Control Functions Refer to drawing B 7880-04-022

This manual section outlines the fea­tures and func­tions of the M7880H communi­cations terminal with operating system software "MTG" #50-715, rel. 1.01 or greater. The operating system soft­ware is installed in the SA14-270G controller assem­bly in EPROM U3.

1) TALK KEYSWITCHES

Sixteen programmable talk keyswitch func­tions are provided, each with a momen­tary pushbutton and a latching pushbutton with an integral LED indica­tor. This keyswitch pair repli­cates the traditional telephone lever key. The lower momen­tary pushbutton acts as the momentary down stroke of the tele­phone lever key. The upper latching pushbutton acts as the up lock position of the lever key, the latch condition is tallied with a red LED indi­cator. Operating the lower momentary pushbutton will cancel the latch condi­tion of the upper push but­ton if it was set.

Fifteen of the talk keyswitches (labelled 1 to 15 are programmable from the cen­tral assignment com­puter. The sixteenth or Call Reply key with its asso­ci­ated Call Assign pushbutton is dedi­cated to answer­ing calls to the com­munications station, that are not assigned to the other keyswitches.

The talk keyswitches may be pro­grammed to talk to a number of stations simulta­neously. This can be done by the Group (GRP) func­tion associ­ated with each ter­minal or by the Call Array (CA) feature. Also they may be pro­grammed via the Event func­tions of the Elec­tronic Peg Board (EPC) to operate any crosspoints in the sys­tem on a co-ordinate basis.

The locking talk keyswitches loop through an external footswitch function that is access­ible on rear connector P2.

If this function is not used a bypass jumper must be installed on P2. As sup­plied a bypass jumper