Figure 2-5. Power Supply Regulator Board (Al)

TM 11-7025-234-23

+10

VDC

TEST POINTS

VOLTAGE

VDC

ADJUSTMENT

VDC

-7

-l0

VDC

NOTE

IF THE POWER SUPPLY

REGULATOR BOARD (Al)

IS REPLACED, THE +7

AND -7 AND THE +10

AND -10 VOLT OUTPUTS

MUST BE ADJUSTED TO

WITHIN ± lOmV.

Power Supply Regulator Board (Al)

b. Control Board (A4). Data, commands, and signals are received by the control

board. Data is handled in or out. This board contains the logic circuitry for the

train function (synchronized between transmitter and receiver). It also contains

the clock timing selector, rate/mode, and configuration control.

Transmitter Board (A7). Data to be transmitted consists of synchronous

(timed) digital Information.

To make it less subject to losses on its line, the

digital signal is coded, scrambled, modulated and digital-to-analog converted.

This data is transmitted at either a 1200, 1600, or 2400 baud rate. Data from the

transmitter then goes to the 1/0 board and out on pins 7 and 8 of J5.

2-8. RECEIVING FUNCTION

Data from a transmitting V.29 modem is received by the remote unit receiver board

(A5). It is then sent through the equalizer (A6), control (A4), and interface (A3)

boards.

a. Receiver Board (A5). Incoming audio signals from the remote modem are

received at terminals four and five of TB-1 or terminals nine and ten of J5. This

input is AGC amplified, analog-to-digital converted and demodulated. It is then

equalized, decoded, descrambled, and sent to the control board. The receiver also

recovers the carrier and timing.

2-8