Service manual

11713A Operating and Service Manual 8-17

Servicing the Attenuator/Switch Driver

Troubleshooting the A4 Local Logic Assembly

The A4 local logic assembly contains a remote/local flip-flop, an A or B

flip-flop, a four-line to ten-line decoder, a local lockout flip-flop, listen

flip-flop, 10 two-line to one-line multiplexers, and the required circuitry

to generate a clock signal to control the operation of the four- to ten-line

decoder.

To Troubleshoot the A4 Local Logic Assembly

1. Make sure that the A3 latch, A5 GPIB, and A7 switch board

assemblies are functioning properly before troubleshooting the A4

local logic assembly.

2. If any of the following conditions cannot be met, replace the A4 local

logic assembly.

a. Turn the driver off and then on. The local light should be on. The

local light should be on.

b. To check the driver in remote operation, use an appropriate

controller to execute the following commands.

Assembly Overview

The remote/local flip-flop is programmed through the GPIB circuitry on

the A5 handshake and data input assembly. If the local lockout flip-flop

is set to a high, the remote local flip-flop cannot be set to local via the

A7 front panel LOCAL pushbutton. In all other cases the A7 local

pushbutton will set the instrument to local.

In local operation, the 10 two-line to one-line multiplexers are set to

propagate and invert the outputs of the monostable multivibrators from

the A7 front panel assembly. The outputs become the clocks for the A3

latch assembly flip-flops. Bus commands determine the state of the A or

B flip-flop which controls the output state of the instrument.

Command Desired Outcome

REMOTE 728

The remote light is on and the local light off.

LOCKOUT 7 Press the local button. Nothing happens.

The local operation is locked out.

LOCAL 7 The local button regains control.

OUTPUT 728;”Al2345678” All attenuator lights should be on.

OUTPUT 728;”B12345678” All attenuator lights should go off.

a. Factory preset GPIB address