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Theory of Operation—2246 1Y and 2246 Mod A Service
Table 3-23
B Sweep Timing Selections
SPEED
1
t i m i n g
C t i m i n g
bsO
bsl
bs2
bs3
bs4
20 ns
2 mA
C329/C330
0
1
1
1
0
50 ns
800 |xA
I I
0
0
0
1
0
100 ns
400 ixA
I I
0
1
0
0
1
100 ms
200 jxA
I I
0
0
1
0
1
100 ms
80 (xA
I I
0
0
0
0
1
1
|XS
40 jxA
I I
0
1
0
0
0
2 |xs
20 |xA
I t
0
0
1
0
0
5 jxs
8 |xA
I I
0
0
0
0
0
10 jxs
4 mA
C307C
1
1
0
1
0
20 |xs
2 mA
I I
1
0
1
1
0
50 |is
800 jxA
I I
1
0
0
1
0
100 )j.s
400 jxA
I I
1
1
0
0
1
100 jxs
200 jxA
I I
1
0
1
0
1
100 jxs
80 jxA
I I
1
0
0
0
1
1 ms
40 jxA
I I
1
1
0
0
0
2 ms
20 |xA
I I
1
0
1
0
0
5 ms
8 jxA
I I
1
0
0
0
0
RUNUP STATE.
With Q304 and Q308 off, the
charging current from the timing circuit can begin
charging the timing capacitors, and the voltage at
the em itter of Q304 ramps up linearly. That ramp is
buffered by the A Sweep Buffer (U310A and B and
Q312) to drive the Horizontal Output Amplifier. As
the ramp is running up, it is being compared with a
fixed reference level by the Sweep End Com
parators. When the ramp level reaches the com
parison level, the A SWP END signal goes high. That
signals the Trigger Logic 1C, U602, to end the A
GATE signal, and the sweep is switched to the
retrace state. The sweep ramp is also being fed
back to the base of Q303. At the point in the ramp
that the base voltage of Q303 exceeds that on the
base of 0302 (the -2 V baseline reference), Q303 is
biased off and Q302 conducts. This biasing con
ditions disables the feedback loop that stabilizes the
baseline voltage level, and it remains off until the
feedback voltage during the retrace period falls back
to near the -2 V baseline reference voltage on the
base of 0302.
RETRACE STATE.
At the end of the sweep, the gate
signals reverse state. Transistor Q309 is biased off,
and Q308 is biased on. Retrace current supplied by
Q308 quickly returns the voltage across the timing
capacitor to a little below the baseline voltage level.
That retrace current is regulated by Q311 and Q326
to produce a rapid, yet rate-controlled retrace. At
the point of the fall in feedback voltage where Q303
starts to turn on, base current becomes available to
Q304 to turn it on, and the feedback loop that
stabilizes the voltage at the baseline level again
becomes active.
3-35
Содержание 2246 1Y
Страница 13: ...2246A Service 7062 01 X The 2246 1Y or 2246 Mod A Portable Oscilloscope ...
Страница 35: ......
Страница 69: ...Theory of Operation 2246 1Y and 2246 Mod A Service 15 V 6081 07 3 32 Figure 3 4 Simplified Sweep Circuit ...
Страница 91: ...Theory of Operation 2246 1Y and 2246 Mod A Service 6081 12 6557 99 3 54 Figure 3 9 Power Supply block diagram ...
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Страница 278: ...Figure 9 5b Detailed 2246 1Y or 2246 Mod A block diagram part 2 R E ...
Страница 287: ......
Страница 304: ...A D D J U N 1991 ...
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 ...
Страница 314: ...15 14 13 12 11 10 9 8 7 6 5 12 11 10 9 8 7 AT117 A TI 271 1 2 3 4 5 6 6555 70 Figure 9 8 Hybrid pin identifiers ...
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Страница 321: ...2246 1Y and 2246 Mod A Service WAVEFORMS FOR DIAGRAM 2 SET READOUT CONTROL CCW OFF 6555 40 ...
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Страница 326: ...A B C P E F G ...
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Страница 343: ...C l rti ...
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 ...
Страница 362: ......
Страница 372: ...2246 1Y and 2246 Mod A Service WAVEFORMS FOR DIAGRAM 9 MORE ...
Страница 373: ... 6555 72 6557 88 ...
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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 ...
Страница 380: ...WAVEFORMS FOR DIAGRAM 10 ...
Страница 387: ...WAVEFORMS FOR DIAGRAM 11 6555 73 6557 48 ...
Страница 394: ...WAVEFORMS FOR DIAGRAM 12 2246 1Y and 2246 Mod A Service i f I S 1 f c i 4 i ...
Страница 395: ...WAVEFORMS FOR DIAGRAM 12 cont 2246 1Y and 2246 Mod A Service ...
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Страница 400: ...REV JUNE 1991 7062 39 ...
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Страница 406: ...B 2246 IV AND 2246 MOD A ...
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Страница 414: ... _ 5 ...
Страница 415: ...2246 1Y 2246 MOD A ...
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Страница 423: ...2246 1Y 2246 MOD A ...
Страница 424: ...2246 1Y 2246 MOD A ...
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