Tektronix 494AP service manual O o a o A o o o o o

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494A1494APServiceVot.I

TABLEOF CONTENTS(Conr.)

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				Page
Section7 THEORY
OF OPERATION(Conr)
FastRetraceBlanking
Memories		...,.,...742
		........		7-47
DEFLECTIONAMPLIFIERS				7-47
Horizontal				,747...
Section
Vertical				....249
Section
Z.AXISANDRFINTERFACE				7-48
RF Interface				7_49
Circuits
Z-AxisCircuits			.....7_49
power-Fail
Detector				7-50
powerSupplyMonitor
			7_50
OptionsSwitch			.....7-50
Timer		..........		7_50
HIGH.VOLTAGE	.............			7.50
SUPPLY
High-Vottage	............			7-50
Osciilator
VoltageDoubter				... 7_SO
High-VoltagRegulator€				7_S0
Z_AxisGtipper		......		7_51
cRT READOUT				7	51
GeneratingReadout				Z_51
R€adout
		.......		Z-S1
OnlOtrTiming
Character				7-Sj
Scan
CharacterGenerator
Timing	.............			z-54
DotDefay		.....-..			2-54
lnstrument		.........		7-56
BusInterface
ControlPort				7-56
Address/DataPort				-Sz
Frequency	...,...,......T
DotMarker
FREQUENCY	.,...........7_57
CONTROL
sEcTtoN				.. 7_60
Sweep				7-60
SpanAttenuator				Z-60
CenterFrequency		........		7-60
Control
1stLO Driver				7-60
preselector
Driver				Z	60
swEEP				7-60
Digital		......		7_61
Controt
SweepGenerator				7	62
TriggerCircuits				....7-62
SweepOutput	.............			7_62
Circuits
MarkerDAC				7-63
SweepControl			.....Z_69
Trigger				Z;.....-69
Control
SweepHoldoff			.....7-64
Interface				7	64
Circuits
spAN ATTENUATOR				7-65
DigitalControl		......		7-65
lnputSection		........		7_65

Digital-to-AnalogConverter.....7_65

DecadeAttenuator...................7 66

		Page
lst LO DRIVER	.........		7-67
DigitalControf	......	7	-6g
InputSwitching		7	-69
OscillatorFilter
SwitchDriver	.......	7-69
SummingAmptifier		7	-69
OscillatorDriver		... 7	-69
Reference		Z-69
Suppty
MixerBias		7	-69
Driver
ProgrammableBias	.................	7	-69
PRESELECTORDRTVER		7	-69
DigitafControlCircuits		7	-70
OscillatorVoltageProcessor... 7-lO
lF Offset	...............		7-21
SummingAmplifier		7	-71
Trackingand
ShaperCircuits		....7-71
CurrentDriver	......	Z-72
PreselectorSwitchDriver.,......7-22
CENTERFREQUENCY
CoNTROL	-		7-72
OperatingModes		7-72
DigitalControl	......	7-73
StorageRegisters..,..,.........7-74
Digital-to-Analog
Converters	.......	7-75
Track-and-HoldAmplifier		7-75
Write-BackCircuit	,...........7-76

-1 0 V ReferenceBuffer.........7-76 COUNTERand PHASELOCK

sEcTroN...7-77 FUNCTIONALDESCRIPTION.......7-77

PhaseLockAssembly.............7-77 FrequencyGontrol...................7-78

Controllingthe OscillatorFrequency......,.,.7,-78Countingthe lF ....................7-78

HARMONICMIXER..7.78 AUXILIARYSYNTHESIZER..........7-79

COUNTERBOARD.,,7.82 AddressDecoder.....................7-82 ServiceRequestCircuits.........7-82

DataBuffers.........7-82 InputAmplifiersand

Multiplexer	7-83
+2nGounter	7.83
21-bitCounter	7-83
PHASELOCKSYNTHESIZER...,..7.83
Synthesizer	7-83
PhaseLock	7-84
OffsetMixer	7-84
ErrorAmplifier	7-85
ControlledOscillator	7-86
StrobeDriverCircuit	7-86

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