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Maintenance— 2236 Service
Test 5— Display Verification
The Display Verification test exercises the display digits
so service personnel can verify correct display operation.
The first part of the test turns on all the segments of each
digit, one digit at a time, from left to right. This verifies that
there are no open connections to the display grids and no
shorts between grid drive lines. It also verifies that all the
segments in each digit can be driven on.
The second part of the test turns on one segment at a
time, in all the digits at once. This is for verifying that there
are no shorts between segment drive lines.
To start the test, set the Channel 1 Input Coupling switch
either to GND or DC position.
Stimulus Loops. To facilitate troubleshooting the CTM
circuitry, there are six fast hardware stimulus loops that can
be individually selected (via the SGL SWP RESET button)
and run. They are designed to exercise a portion of the cir
cuitry in a known, repeating pattern (all except Stimulus
Loop 6). A stable trigger signal is provided, so that the tim
ing relationships of various signals can be viewed and com
pared on a test oscilloscope.
When a particular stimulus loop is selected, the readout
will display “Sn" when the loop is not running, where “n” is
the stimulus loop number (1 through 6). A stimulus loop is
started by changing the Channel 1 Input Coupling switch
setting from the AC position to the GND or DC position. To
stop a stimulus loop, return Channel 1 Input Coupling switch
back to the AC position. When a stimulus loop is started,
the readout will go blank (for stimulus loops 1 through 5).
The selected stimulus loop must be stopped before another
stimulus loop can be selected.
Stimulus Loop 1
Stimulus Loop 1 selects Period measurement mode for
the counter front end and performs measurements on the
internal firmware-generated test signals. See Figure 6-2 for
Period test waveforms and their location. The positive-going
pulse at TP1500 (TRESET) can be used as a trigger signal.
Stimulus Loop 2
Stimulus Loop 2 selects Width measurement mode for
the counter front end and performs measurements on the
test signal. See Figure 6-3 for width test waveforms and
their location. The positive-going pulse at TP1500
(TRESET) can be used as a trigger signal.
Stimulus Loops 3, 4, and 5
These stimulus loops exercise the DMM serial interface
by sending out a particular control word repetitively. Stimu
lus Loop 3 transmits 55 hex, Stimulus Loop 4 transmits AA
hex, and Stimulus Loop 5 transmits FI hex which is the
control code that turns on the Ohms AC modulation source
(used during diode test). Stimulus Loop 5 facilitates trouble
shooting the diode test ciruitry in the DMM.
Stimulus Loops 3, 4, and 5 allow service personnel to
troubleshoot the optoisolator interface and check the shift
register receiver (U1906) for proper operation. See Figure
6-4 for the test waveforms and their locations. As with Stim
ulus Loops 1 and 2, the positive-going pulse at TP1500
(TRESET) can be used as a stable trigger signal for viewing
the test waveforms.
Stimulus Loop 6
In Stimulus Loop 6, the DMM hardware is set up to mea
sure diode forward-drop voltage as in the diode test in resis
tance measurements. To verify the forward-drop measure
ment accuracy, perform the following procedure.
1. Set:
Channel 1 Input Coupling
GND
UPPER FUNCTIONS-
LOWER FUNCTIONS
IN
Function Select
DCV
2. Observe that the display on the readout is “Fd .000”.
3.
Apply a 2 V signal from a calibrated source to the
Multimeter input connectors.
4.
Read the voltage on the readout and verify measure
ment accuracy.
6-18
Содержание 2236
Страница 10: ...2236 Service viii The 2236 Oscilloscope ...
Страница 28: ...Specification 2236 Service 1 18 ADD JAN 1985 Figure 1 2 Physical dimensions of the 2236 Oscilloscope ...
Страница 74: ...Theory of Operation 2236 Service 3 30 ...
Страница 75: ...Theory of Operation 2236 Service Figure 3 13 Typical waveforms for the Delta Time function with Valt HI 3 31 ...
Страница 102: ...Performance Check Procedure 2236 Service 4 21 Figure 4 1 Test setup for DMM common mode check ...
Страница 240: ...2236 Service CTM INTERFACE SIGNALS F ig u re 9 4 O s c illo s c o p e b a sic b lo c k diag ram 4294 46 ...
Страница 241: ... VERT DEFL 2236 Service 4 2 0 6 3 5 4 2 0 4 4 7 F ig u re 9 5 O scillo sco p e d e ta ile d b lo c k diag ram ...
Страница 242: ...2236 Service 4204 34 Figure 9 6 CTM basic block diagram ...
Страница 243: ...DMM POWER S U P P LIE S 2236 Service F ig u re 9 7 C T M d e ta ile d b lo c k diag ram ...
Страница 253: ...A10 COUNTER TIMER MULTIMETER BOARD F ig u re 9 8 C irc u it b o a rd lo c a tio n Illu s tra tio n ...
Страница 254: ...S I 0 O I 5 1 S O i 4204 21 C IR C U IT BOARD INTERCONNECTIONS ...
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Страница 319: ...2236 Service TROUBLESHOOTING GUIDE 4206 99 4204 69A ...
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