Tektronix 2236, Instruction Manual

Page: 144 / 350

Maintenance— 2236 Service
2. The readout will display “SELF-tESt”. The instrument
is now ready to perform the Diagnostic Routine.
3. Press in the SGL SWP RESET button momentarily to
enter the first Check Routine.
Check Routines. The Check Routines consist of three
checks; one looks at the ROM headers and the others
check the front-panel controls that are CTM related. The
three Check Routines are called up in the following
sequence.
Check 1 -Software Version Readout
This check displays on the readout the software version
and revision numbers which are stored in the headers of the
8K ROM and the 2K ROM.
The readout will display “A.ABB C.CDD” where “A.A
and C.C" are the version numbers in the 8K ROM and 2K
ROM headers respectively, and “BB and DD" are the re­
spective revision numbers. The version and revision number
of the 8K ROM should match the 2K ROM.
Check 2— Front Panel Control Verification
This check continuously monitors and displays the status
of the Function Select switches and the HORIZONTAL
MODE switch.
The readout will display “X YYYYYY” where “X” repre­
sents the HORIZONTAL MODE switch, and “Y” represents
CTM Function Select switches in a left-to-right sequence.
See Table 6-5 for the Front Panel Control Verification
readout.
Table 6-5
Control Switches Verification Readout
Front Panel Controls Display
“X” Horizontal Mode
A
0
ALT or B 1
“Y" Function Select switches
Out
0
In
1
Check 3— Channel 1 Logic Verification
This check continuously monitors and displays the status
of the Channel 1 Input Coupling switch, Channel 1 probe,
and CH 1 VOLTS/DIV switch.
The readout will display “CX PX AXX” where “C” repre­
sents the Channel 1 Input Coupling switch, “P” represents
the probe, and “A” represents the CH 1 VOLTS/DIV switch
(attenuator). The “X” represents the logic (1 or 0) of the
Channel 1 Input Coupling switch, probe, and CH 1
VOLTS/DIV switch. See Table 6-6 for the Channel 1 Logic
Verification messages.
Table 6-6
Channel 1 Logic Verification
Channel 1 Controls
and Probe
Display
Channel 1 Input
Coupling Switch
AC CO
GND-DC
Cl
Channel 1 Probe
IX P0
10X PI
CH 1 VOLTS/DIV
2 mV to 50 mV A ll
0.1 V to 0.5 V A01
1 V to 5 V A10
Test Routines. The Test Routines consist of five
selectable tests (tl through t5). Initially, set the Channel 1
Input Coupling switch to AC position. The test message dis­
played on the readout will be “tX
Y" where “X” is the
test number and “Y” is either an “S” (single pass mode) or
an “L” (looping mode). The selected test is started by mov­
ing the Channel 1 Input Coupling switch to either GND or
DC position. In single pass mode, the test executes only
once. Looping mode allows the test to automatically repeat
itself until stopped (by returning the Channel 1 Input Cou­
pling switch to AC).
Each test will halt its test sequence at the first error de­
tected except in looping mode, where the test repeats itself
after displaying the error code for a short period. This allows
the examination of the state of the circuitry when the first
error was discovered. To interpret the error codes displayed
by the test routines, compare the test messages on the
readout with the appropriate table (Tables 6-5 through
6
-
10
).
After performing each test, return the Channel 1 Input
Coupling switch to the AC position to either continue with
the next test or advance to the Stimulus Loops . The front-
panel controls should be set as follows before executing
Test 1 through Test 5.
6-12