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Maintenance—2246 1Y and 2246 Mod A Service
1. Power-up Tests
When the instrument power is applied, self tests are
automatically run to verify proper operation of the
system RAM and ROM and readout interface
circuitry. If the pow er-up test fails, failure codes
appear in the Trigger Mode LEDs to identify the
general location of the fault. (See Power-Up Testing
later in this section for failure-code information.)
2. Diagnostic Routines
Various diagnostic routines can be run from the
service mode. The routines can be run at any time
by displaying the SERVICE MENU and selecting the
desired item from the menu using front panel
pushbuttons.
Entry into the SERVICE MENU and its uses are
explained in the Diagnostic Routines discussion later
in this section.
3. Check Control Settings
Incorrect control settings can give a false indication
of instrument malfunction. If there is any question
about the correct function or operation of any con
trol, refer to the Operating Information in the 2246
1Y and 2246 Mod A Operators Manual.
4. Check Associated Equipment
Before proceeding, ensure that any equipment used
with the 2246 1Y or 2246 Mod A is operating cor
rectly. Verify that input signals are properly con
nected and that the interconnecting cables are not
defective. Check that the ac-pow er-source voltage
to all equipment is correct.
5. Visual Check
W A R N IN G
To
avoid electrical shock, disconnect the
instrument from the ac power source before
making a visual inspection of the internal
circuitry.
Perform a visual inspection. This check may reveal
broken connections or wires,
damaged com
ponents,
semiconductors
not firm ly mounted,
damaged circuit boards, or other clues to the cause
of an instrument malfunction.
6. Check Instrument Performance and
Adjustment
Check the performance of either those circuits
where trouble appears to exist or the entire instru
ment. An apparent trouble may be the result of
misadjustment. The complete performance check is
given in Section 4 of this manual and adjustment
instructions are given in Section 5.
7. Isolate Trouble to a Circuit
To isolate problems, use any symptoms noticed
when checking the instrum ent’s operation to help
localize the trouble to a particular circuit. For exam
ple, if the vertical deflection is incorrect on all chan
nels, the problem is most likely from the delay line
driver to the vertical output; if deflection is bad only
on one channel, the problem is from the attenuator
of that channel to the input of the delay line driver.
The detailed block diagram shown in the foldout
section may be used as an aid in determining signal
flow and control line dependency for correct circuit
operation. Refer to the troubleshooting hints given in
Table 6-6 for diagnostic routine failures. Trouble
shooting hints by diagram are given immediately fol
lowing Table 6-6, and Table 6-9 may be used to aid
in locating a problem in the measurement system.
8. Check Power Supplies
W A R N IN G
For safety reasons, an isolation transformer
must be used between the ac power main
and the instrument’s ac power input when
ever troubleshooting is done with the cabinet
removed. This is especially important when
working in the Preregulator and Inverter
Power Supply sections of the instrument.
When trouble symptoms appear in more than one
circuit, first check the power supplies; then check
the affected circuits by taking voltage and waveform
readings. Check first for the correct output voltage
of each individual supply. These voltages are
measured between J1204
(interface connector
between power supply and main board) and ground
(J1204 pin 4 or 8). See the associated circuit board
illustration and Table 6-4.
Voltages levels may be measured either with a DMM
or with an oscilloscope. Voltage ripple amplitudes
must be measured using an oscilloscope. Use a IX
probe with as short a ground lead as possible to
minimize stray pickup.
6-7
Содержание 2246 1Y
Страница 13: ...2246A Service 7062 01 X The 2246 1Y or 2246 Mod A Portable Oscilloscope ...
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Страница 69: ...Theory of Operation 2246 1Y and 2246 Mod A Service 15 V 6081 07 3 32 Figure 3 4 Simplified Sweep Circuit ...
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Страница 311: ...2246 1Y and 2246 Mod A Service WAVEFORMS FOR DIAGRAM 1 0 V r l III B f e I l i 6555 39 ...
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Страница 344: ...WAVEFORMS FOR DIAGRAM 5 2246 1Y and 2246 Mod A Service HORIZ MODE A A SEC DIV 2M S HOLDOFF MIN CCW ...
Страница 345: ...HORIZ MODE ALT A SEC DIV 2M s B SEC DIV 5 mS HOLDOFF MIN DELAY INTENSIFIED ZONE STARTS MIDSCREEN ...
Страница 347: ...BEV JUNE 1991 7062 18 ...
Страница 349: ...2246 1Y and 2246 Mod A Service WAVEFORMS FOR DIAGRAM 6 6555 43 I ...
Страница 354: ...A L B i C 1 D 1 E i F i G 1 2 3 4 5 6 7 8 2246 1Y AND 2246 MOD A _________A fc A A REV JUNE 1991 7062 19 ...
Страница 355: ...I BOARD LOCATION 8K 8J 8H 7H 8H 8H 7J 8D 7H 8H 8J 8J 7K 8K 10D 6L 6K 6L 6K 6G 5H I ...
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Страница 376: ...SCHEM LOCATION BOARD LOCATION 2E 2B 7F 4B 4J 5D 3J 5C 4L 6D 3L 6C 5L 7D 3L 7D 3M 7D 5M 7D IB 1A 1C 1A 2B 1A 3B 1A ...
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Страница 395: ...WAVEFORMS FOR DIAGRAM 12 cont 2246 1Y and 2246 Mod A Service ...
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