Tektronix 567 User manual

INSTRUCTION
MAN UAL
Tektronix, Inc.
Serial Number
TYPE 567
READOUT
OSCILLOSCOPE
S.W. Millikan Way @ P. O. Box 500 @ Beaverton, Oregon 97005 ® Phone [phone] @ Cables: Tektronix
070-0322-01
965

ype and Serial nu
for baeeen i

SECTION 1
CHARACTERISTICS
General Information
The Tektronix Type 567 Readout Oscilloscope is the
power supply and indicator unit for a complete system
that provides digital readout of signal information. The two
smaller plug-in cells accept any of the Tektronix 2 or 3
Series plug-in units. The large plug-in cell accepts the
Tektronix 6 Series digital units. The digital units are com-
patible with some (but not all) of the 2 or 3 Series units.
See your Tektronix Field Engineer for details. Without the
digital unit, the Type 567 will operate in the normal oscillo-
scope manner. With the digital unit, the system can readout
its own display of risetime, amplitude or time difference for
either conventional voltage-time displays or sampling equiva-
lent-time displays. The system provides “go, no-go" signals,
and can be programmed automatically using up to three
Tektronix Type 262 Programmers.
ELECTRICAL CHARACTERISTICS
Power Supplies
Electronically regulated for stable operation with widely
varying line voltages and loads.
Line voltage requirements—105 to 125 volts, or 210 to
250 volts, rms, 50 to 60 cps, single-phase ac.
Power—Approximately 400 watts when using the Type
3876, 3177 and 6R1A Plug-in Units.
Fuse—4 Amp Fast-Blow for 117 volts, 2 Amp Fast-Blow
for 234 volts.
Cathode-Ray Tube
Type—T5032-2-1 (S/N 1999-up}
5610-31 (S/N 750-1998}
T5031-2 {S/N 101-749)
Phosphors—Standard phosphors as listed above, others
available as listed with accessories at end of this section.
Unblanking—Deflection type, de coupled.
Accelerating potential—Approximately 3.5 kv.
Usable viewing area—8 divisions vertical by 10 divisions
horizontal.
Deflection plate deflection factors (nominal at 3.5 kv)
(S/N 1999-up (S/N 101-1998}
19.5 volts/div 22.8 volts/div
Horizontal—18.4 volts/div 18.4 volts/div
Vertical—
Graticule
Internal within ert (S/N 1999-up)
External plastic (S/N 101-1998}
®1
I{lumination—Variable edge lighting.
Markings—Marked in 8 vertical and 10 horizontal 1-centi-
meter divisions with 2-millimeter markings on the centerlines.
Amplitude Calibrator
(S/N 2060-up). A square wave with accurate time
duration and amplitude; intended for use when setting the
vertical and horizontal plug-in units front-panel calibrate
controls. Two output frequencies, an accurate 20 kc and an
approximate 1 kc. The 1-kc square wave is valuable when
adjusting low-frequency attenuator probes.
Output Voltage—Separate BNC connectors produce
ground-referenced 0.5 and 5 volts peak to peak when loaded
(one or both at the same time) by 100k or greater. Same
connectors provide 50 and 500 mv peak to peak when loaded
{one at a time) by 50 ohms.
Accuracy—Voltage accurate to --2% peak to peak into
100k or greater loads. Voltage accuracy into 502 depends
on load resistor: -—-2% peak to peak when 50 is within
1% at one output connector at a time.
Frequency of 20-kc square wave is within 0.1% when the
l-ke square wave is within +80% and —40%; symmetry
not specified for either frequency.
+Pre Trigger—A short-duration, ground-referenced, posi-
tive pulse at least 600 mv peak to peak into 100k or greater,
that occurs approximately 1%, cycle ahead of each plus rise
of square-wave signal. Amplitude is reduced by 502 load,
but +Pre Trigger signal is intended for externally triggering
the time-base units of sampling systems not employing an
internal trigger pickoff.
All three output connectors of the Amplitude Calibrator
are short-circuit proof. External short circuits will not damage
the calibrator circuits.
(S/N 101-299). Waveform—Square waves at line fre-
quency.
Output Voltage—0.05, 0.5, 5 and 50 volts, peak to peak
into 1 meg or greater load, one at a time.
Accuracy—Peak-to-peak amplitude of square waves within
3% of indicated voltage.
(S/N 300-2059). Above characteristics plus 100-mv
peak-to-peak square wave available from 0.5 jack when
loaded with 1% 509.
Ventilation
Forced, filtered air. A thermal relay interrupts instrument
power in the event of overheating. Fan remains on if thermal
relay opens during 117-volt operation. Fan turns off. if
thermal relay opens during 234-volt operation. Temperature
of the thermal relay must drop about 15° F before power
will be restored.
1-1

Characteristics—Type 567
MECHANICAL CHARACTERISTICS
The Type 567 is constructed with aluminum-alloy chassis
and cabinet. Cabinet is finished with a durable blue vinyl
plastic. The unit sits on short anti-slide neoprene feet.
Cabinet dimensions—Height 135/,”, width 17”, depth 23”.
Accessories
Information on accessories for use with this instrument is
included at the rear of the mechanical parts list.
®i

SECTION 2
OPERATING INSTRUCTIONS
General Information
The Type 567 is a specially designed oscilloscope for
producing digital display of information which can be
obtained only from the crt on an ordinary oscilloscope. The
digital readout system can be made to display either voltage
or time, and may be used for such applications as measuring
the peak-to-peck amplitude of a waveform, or its risetime.
IF dual-trace plug-in units are used with the Type 567, the
digital readout system can be used to obtain both voltage
and time measurements on either trace, In addition, the
digital readout system will make time measurements between
signals displayed on one trace and signals displayed on
the
other.
The Type 567 and associated units are relatively easy to
operate once the basic operating procedures are understood.
It is the purpose of this section ond similar sections in the
plug-in unit manuals to establish the proper operating tech
niques. This
manual covers instructions for the Type 567
‘only. For operating instructions for the plug-in units, refer to
the applicable instruction manuals.
Preliminary Instru
Before operating the Type 567, a suitable location for the
instrument must be chosen. The location should provide a
stable support for the instrument. Care should be taken that
adequate air circulation is permitted through the instrument
by keeping it away from walls, or from other equipment
which might block the air intake through the filter or the
exhaust passages in the cabinet. If the flow of air over the
components in the unit is interrupted, overheating of the
instrument may cause a thermal relay in the instrument to
open, shutting down the instrument.
ns
The Type 567 Oscilloscope can be operated from 110,
117,
or 124 volts, or 220, 234, or 248 volts. The only changes
necessary to convert from one operating voltage to another
are in the wiring of the power transformer primary and the
fan
motor. The power transformer used in the Type 567
Uses two separate primary windings plus two 6% boost-buck
windings. The primary windings are connected in parallel
for 117-volt operation and in series for 234-volt operation:
Proper connections for each line voltage are shown on the
side of the power transformer and on the Power Supply
schematic.
A small metal tag near the power receptable at the rear
of the instrument indicates the line voltage for which the
instrument was wired at the factory. If wired for 117 volts,
the instrument will operate properly with line voltages be-
tween approximately 105 and 125 volts. If wired for 234
volts, the instrument will operate properly from approximately
210 to 250 volts.
Jo change the power transformer connections for opera:
tidn on another line voltage, change the location of the
bare
wire
straps
at
the
primary
terminals,
It
is
not
necessary
to move any of the plastic insulated wires. Place the new
straps in accordance with the markings on the tag located
fon the power transformer side.
When a suitable location has been chosen, set the POWER
ON switch to the off position and connect the instrument to
{an appropriate source of power. Place the desired vertical
plugin unit (for example, the Type 3A2 or 3876) in the left
plug-in compartment of the oscilloscope (see Fig. 2-1). Place
the horizontal plug-in unit (for example, the Type 382 or
3177) in the center compartment. Finally, place the desired
digital unit (for example, the Type éRI or 6RIA) in the right
compartment of the oscilloscope. Make certain all units are
properly inserted and locked in place before turning on the
oscilloscope power. The horizontal and vertical. plug-in
units are locked in place by turning the front-panel knurled
‘aluminum locking knobs clockwise. The digital unit is locked
in place by removing the right side panel and tightening the
two fasteners at the rear of the compartment.
Fig. 2-1, Type 567 plug-in co yartments
Checking Plug-In Ui
Each vertical, horizontal and digital plug-in unit must
be calibrated within the particular oscilloscope in which it
is to be operated. Units purchased as a system (oscilloscope
‘and three plug-ins) are calibrated together as a system at the
factory, Units purchased separately, or calibrated separately,
must have their basic gain adjusiments made when they
are installed
Accuracy
Individual oscilloscope crt deflection factors differ within
normal limits. The vertical and horizontal units have front:
panel Calib controls so the particular amplifier gain can be
set to that needed by the crt. Some sampling plug-in units
have internal digital gain controls that must be correctly
adjusted. See the individual plug-in unit instruction manval
calibration procedure for details.
The digital unit is sensitive to the oscilloscope power-supply
voltages. Digital readout accuracy is closely related 10
power-supply voltage accuracy. Since it is impossible to
21

Operating Instructions—Type 567
make all Type 567 Oscilloscope power supplies to have
exactly the same voltage accuracy, the digital unit must be
calibrated in the oscilloscope in which it is used. If a cali-
brated digital unit (either Type 6R1 or 6RIA) is placed into
another Type 567 Oscilloscope, check the accuracy of the
start and stop voltages and the rate of rise of the voltmeter
ramp before relying on either time or voltage readout.
See the digital unit instruction manual calibration procedure
(Type 6RIA steps 5 and 6; Type 6R1 steps 15 and 17} for
details.
Intensity Control
The INTENSITY control is used to adjust the brightness
of the oscilloscope display. Begin with INTENSITY control
counterclockwise, because some plug-ins permit a_ bright
spot during warm up. After turning on the instrument and
waiting a few minutes for warm up, free run the oscilloscope
sweep by setting the TRIGGER SENSITIVITY or LEVEL control
fully clockwise. Adjust the INTENSITY control for a suitable
trace intensity.
Do not leave a bright, sharply focused spot on the crt
screen for a prolonged period. An excessively bright sta-
tionary spot may damage the crt phosphor.
Focus and Astigmatism Controls
The FOCUS and ASTIGMATISM controls are used in con-
junction with each other to produce a well-focused display
on the oscilloscope screen. Because changes in the setting
of the INTENSITY control may affect focus slightly, the trace
should be focused with the actual waveform displayed and
with the desired intensity setting. Refer to the appropriate
plug-in manuals for instructions for applying a signal to the
oscilloscope and obtaining a stable display. With a signal
displayed, carefully adjust the FOCUS and ASTIGMATISM
controls alternately for best possible focus over the entire
display. There is an intensity level above which a good
focus is impossible to attain.
Scale Illumination Control
The ert graticule is edge-lighted by two small lamps at
the bottom. The lighting can be adjusted to suit the ambient
light conditions by means of the SCALE ILLUM control.
Rotating the control clockwise increases the brightness of
the graticule scale markings. The graticule is marked with
eight 1-centimeter divisions vertically and ten 1-centimeter
divisions horizontally, with 2-millimeter markings on the
centerlines.
Changing Plug-In Units
Horizontal and vertical plug-in units used in the Type 567
may be changed at any time. However, it is recommended
that the instrument be turned off while a change is made.
This affords maximum protection to the oscilloscope and
other plug-in units against sudden transients and load
changes.
Whenever a horizontal or vertical plug-in unit is changed,
it is important that you check both the gain and timing of
the oscilloscope. This will ensure accurate measurements.
2-2
Se LR Ao
Amplitude Calibrator (SN 2060-up)
The Amplitude Calibrator provides a choice of four square-
wave voltages with amplitude tolerance of +2%. 0.5 and 5
volts peak to peak when loaded (one or both at the same
time) by 100k or greater, and 50 and 500 mv when loaded
(one at a time) by 502 +1%. Two frequencies are avail-
able: crystal-controlled 20-kc {=:0.1%) square waves, and
1-ke (--20%) square waves. The two frequencies are select-
able by a front-panel 20 KC-==1 KC toggle switch. The volt-
age accuracy of any one of the four output voltages may be
adjusted to within —%% by special calibration.
The Amplitude Calibrator is valuable for adjusting the
front-panel Calib controls of both vertical and horizontal
real-time or sampling plug-in units. The 20-ke frequency (and
the ability to make one of the output voltages very accurate}
permits checking the system operation including digital unit
time and voltage readout. The 1-ke frequency is valuable
for compensating low-frequency attenuator probes.
Front-panel BNC connectors permit convenient 50 cable
connection of calibrator signals to the plug-in unit input
terminals, or to external equipment. If the vertical plug-in
unit has a high-impedance input, the two higher square-wave
voltages will apply. Addition of an external 50Q termina-
tion (Tektronix Part No. 011-0049-00) at the plug-in input
connector will provide the two lower voltages. If the plug-in
unit has an internal 50 Q termination, do not add the external
termination when accurate voltages are desired. (Actually,
the Amplitude Calibrator is short-circuit proof, so any load
is permissible, but accurate voltages are obtainable only as
above.)
The +Pre Trigger connector delivers a positive pulse ap-
proximately 4 cycle before each positive step of both the
20-kc and 1-kc square-wave signals. Sampling plug-in time-
base units can effectively use the +Pre Trigger signal (at
20 kc) for external triggering. A positive step will then appear
near the beginning of the display, produced without external
delay cable in the pretrigger signal path.
(S/N 300-2059)
The Amplitude Calibrator provides a choice of four square-
wave signals with peak-to-peak voltages of 0.05, 0.5, 5
and 50 volts --3% when loaded by 1 megohm or greater.
In addition, a signal of 100 mv peak to peak +3% into a
502 (1%) resistance is provided from the 0.5 jack. This
voltage is valuable for checking the vertical calibration of
sampling plug-in units. Frequency of the square wave is
that of the power line.
(S/N 101-299)
The Amplitude Calibrator provides a choice of four square-
wave signals with peak-to-peak voltages of 0.05, 0.5 5 and
50 voits +3% when loaded by 1 megohm or greater. Fre-
quency of the square wave is that of the power line. The
Amplitude Calibrator is valuable for checking real-time plug-
in unit calibration and the compensation of attenuator probes.
It is also valuable as a time reference for adjusting the
horizontal unit calibration; three complete cycles at 60 cps
line frequency occur’ in 50 milliseconds (2 cycles at 50 cps
line frequency occur in 40 milliseconds).

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75
LOAD
CURRENT
OF
ONE
PLUG-IN
UNIT
(Milliamperes)
Fig. 2-2. —100-volt supply shunt.
Skeleton Plug-In Units
Skeleton plug-in units for the vertical and horizontal sec-
tions are available for all of the Tektronix Type 560 Series
oscilloscopes, including the Type 5467. None are available for
the large plug-in area used for digital readout. These skele-
ton units permit you to build your own plug-in circuitry for
use in the Type 567. If you use your own circuitry, pro-
vision may be made for operating the digital readout cir-
cuits, although this is not necessary. Order the skeleton
chassis as Modification Kit number 040-0245-00 from your
local Tektronix Field Office.
A dummy cover is available for the digital cell. Order by
Tektronix Part No. 016-0051 -00.
Power Supply Capabilities
The total de power available for vertical and horizontal
plug-in use is 85 watts divided between four regulated sup-
plies. The remaining power available must be reserved for
the digital units. Use of current from any of the unregulated
de supply leads is not recommended.
The four regulated de supplies listed in Table 2-1 are em-
ployed by the X and Y axis amplifiers.
Since the Type 567 indicator unit employs two plug-in
units to operate the X and Y axes of the crt, currents listed
in Table 2-1 are normally divided between them. However,
a single plug-in alone can be used, such as a vertical ampli-
fier, with moving-film recording used instead of a horizontal
sweep. In such a case, it will be necessary to elevate the
crt horizontal deflection plates to approximately +180 to
On
Operating Instructions—Type 567
TABLE 2-1
Type 567 Power Supply Current
Capabilities For X and Y Plug-In Units
Supply Max. Total Connector
Current Terminals
Reg. —100 vdc 130 ma 23— to 9 ground
Reg. —12.2 vdc 1.5 amps 16— to 5 ground
~ Reg. +125 vde _ 150 ma 15+ to 9 ground
Reg +300 vde 150 ma 10+ to 9 ground
5 amps per
Unreg. 6.3 vac plug-in 1-2
+210 volts de to permit proper focus and astigmatism
control.
The limit of the amount of power which can be dissipated
in one plug-in unit is based primarily upon the ambient
temperature and amount of ventilation supplied. Vacuum
tubes should not be operated with envelope temperatures
above 150° C when the ambient temperature is at 25° C,
or above 175° C when the ambient temperature is at 50° C.
The Type 567 indicator unit can be operated in ambient
temperatures up to 45°C.
Separate terminals are provided for the ground return of
the —12.2-volt regulated heater supply. When using this
supply in your own plug-in design, it is best to run two leads
to the heater terminals so that the ground lead can be
connected directly to terminal 5, thus eliminating ground
currents.
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qT qT T T qT Li LU T L qv Lu qT
0 25 50 75
LOAD CURRENT OF ONE PLUG-IN UNIT
(Milliamperes)
Fig. 2-3. + 125-volt supply shunt.
2-3

Operating Instructions—Type 567
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25 50 75
LOAD CURRENT OF ONE PLUG-IN UNIT
(Milliamperes)
Fig. 2-4. +300-volt supply shunt.
above 150° C when the ambient temperature is at 25° C,
or above 175° C when the ambient temperature is at 50° C.
The Type 567 indicator unit can be operated in ambient
temperatures up to 45°C.
Separate terminals are provided for the ground return of
the —12.2-volt regulated heater supply. When using this
supply in your own plug-in design, it is best to run two leads
to the heater terminals so that the ground lead can be
connected directly to terminal 5, thus eliminating ground
currents.
TABLE 2-2
Recommended Type 567 Regulated
Power-Supply Shunt Resistors?
Shunt Resistor
Values —100v +125 v +300 v
No Shunt | 0 to 25ma| 0 to 45ma| 0 to 40ma.
20009, 5w_ be-
tween proper ter | 99 +9 45ma|25 to 60ma 35 to 67ma
minals of power
connector. _
SHORT,
between proper
terminals of pow- | 40 to 65ma/50 to 75 ma |65 to 75 ma
er connector.
1Currents listed are one-half total available, based on two plug-
in units being used.
Suggested Power-Supply Shunt Resistor Values
To make efficient special use of the Type 567 indicator
unit power supply, the load currents and maximum or mini-
mum load values must be known.
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Terminals X, Y¥, and Z are
located in plug-in units X = +300-Volt Shunt
Y = +125-Volt Shunt
Z = —100-Volt Shunt
Fig. 2-5. Power-supply shunt resistor connections.
The nature of series-regulated power supplies permits ob-
taining more current from them than can normally be handled
by the series tube alone (providing the power transformer
and rectifiers can supply more current). By placing a shunt
resistor of appropriate value across the series regulator tube,
additional current can be made available for the load. The
correct value shunt resistor must be chosen to permit the
regulator system to deliver current with low ripple, and the

Use of shunt-resistor values suggested in Table 2-2 will
lead to a minimum of total power required, and give lowest
plug-in temperature. It is the simplest method that will not
overtax supplies, either for regulation or temperature. How-
ever, if Table 2-2 does not meet your design needs, refer
to the curves of Figs. 2-2, 2-3, or 2-4 to aid your choice of
individual power-supply shunt resistors. Always plan the
shunt
to
permit
lowest
plate
dissipation
in
the
series
regulator
tube consistent with proper regulation and ripple values.
A portion of the power-supply schematic has been re-
produced in Fig. 2-5, identifying interconnecting plug termi-
nals
specified
in
Table
2-3.
J11
and
J21
are
the
horizontally-
mounted interconnecting plugs at the rear of the vertical and
®)1
Operating Instructions—Type 567
horizontal plug-in cells, respectively. Do not use shunt re-
sistors in the digital cell at J31.
TABLE 2-3
Plug-In Interconnecting Plug Terminals
For Regulated Supply Shunt Resistors
In X and Y Amplifiers
Supply Terminals
—100 22—9 return
+125 20—15 return
+300 6—10 return

NOTES

SECTION 3
CIRCUIT DESCRIPTION
General Information
The Type 567 Oscilloscope consists of three major parts:
the low-voltage power supplies, the crt circuits, and the
Amplitude Calibrator. The oscilloscope is essentially an indi-
cater and power supply for the plug-in units used with the
instrument. Vertical and horizontal plug-in units drive the
deflection plates of the crt directly, and also drive the digital
unit.
The low-voltage power supplies provide outputs of —100,
—12.2, +20, +125, and +300 volts.
The crt circuits contain the high-voltage power supply and
crt. The high-voltage supply provides regulated 3.3-kv poten-
tial to the crt cathode.
The Amplitude Calibrator generates square waves with
calibrated amplitudes at either 20 kc or 1 ke. The calibrator
square waves are used as a convenient signal source to
verify the calibration of the vertical, horizontal, and digital
plug-in units.
Low-Voltage Power Supplies
Low-voltage power supplies of the Type 567 supply all
the power to the high-voltage power supply, the Amplitude
Calibrator, and the three plug-in units. Each regulated output
voltage is stable over the line voltage range of 105 to 125
volts rms, or 210 to 250 volts rms, centered at either 117 or
234 volts 50 to 60 cps. The supplies will remain within
regulation for line-voltage distortion up to about 5%.
All regulated power supplies are referenced to V609 of
the —100-volt supply; the output voltage of the —100-volt
supply is the reference voltage for all other regulated
supplies.
Vertical and horizontal plug-in units use power from all
but the +20-volt supply. The +20-volt supply is used by
the digital unit and can be used externally through the
digital unit (Type 6R1 or 6RIA J34-G) at currents up to
500 ma.
Three of the power supplies include shunt resistors that
allow more current to be drawn than can be handled by
the series regulators alone. A discussion of power-supply
loads and shunts is included in the section on Operating
Instructions.
—100-Volt Power Supply
Line voltage is applied through fuse F601 and the ther-
mal cutout relay TK601 to the primary windings of T601.
This energizes the secondary windings of T601. Terminals 19
and 20 of T601 apply power to a full-wave bridge rectifier
consisting of D602A, B, C, and D. The unregulated output of
the rectifier circuit is applied to the —100-volt regulator cir-
cuit and through the interconnecting plugs to the plug-in
units.
Voltage regulator tube V609 maintains the grid of V616B
at approximately —85 volts. The voltage at the grid of
V616A is obtained from a divider between ground and the
—100-volt output of the regulator. V616 is a cathode-coupled
difference amplifier which compares the voltage at the grid
of V616A against the fixed —85 volts at the grid of V616B.
Potentiometer R624 sets the output of the power supply at
—100 volts.
If the output voltage tends to change from —100 volts,
a sample of the change is applied through the divider to the
grid of V616A. This error signal is amplified and inverted
by V616A and applied to the base of Q624. Q624 amplifies
and inverts the error signal and applies it to the grid of
series regulator V627A. The change in grid voltage of V627A
changes the voltage drop across the tube and causes the
output voltage to return to normal.
Capacitor C625 increases the ac loop gain of the regulator
circuit. Its function is to quickly compensate for rapid changes
in the output voltage. The higher ac loop gain provided by
C625 also reduces ripple at the output of the regulator.
C626 aids in reducing the ac output impedance of the —100-
volt supply.
+125-Volt Power Supply
A full-wave bridge rectifier circuit from terminals 33 and
34 of T601 supplies power to the +125-volt regulator cir-
cuit and to the plug-in units through the interconnecting
plugs. The +125-volt supply compares its own output volt-
age with the —100-volt supply through the resistive voltage
divider R674-R675. The divider supplies a voltage near
ground to the grid of V664. If the output voltage from
the regulator changes, a portion of this change is applied
through the divider to the grid of error amplifier V664. The
error signal is amplified by V664 and applied to the grids
of series regulator V677. The change in voltage at the grids
of V677 changes the voltage drop across V677 and compen-
sates for the change in output voltage.
The screen supply for V664 is obtained primarily from
the output of the regulator circuit. R665 applies ripple from
the unregulated bus to the screen as a signal voltage.
The ripple is amplified and helps to reduce ripple appearing
on the output.
Capacitor C674 is used to increase the ac loop gain of
the regulator circuit. This allows the circuit to recover
rapidly from sudden changes in output voltage. The increased
ac loop gain also helps to reduce the ripple at the output
of the regulator. C676A reduces the ac impedance of the
+125-volt supply. Resistors R671 and R676 in the cathodes
of the series regulator V677 tend to balance the current
through the two sections of the tube.
On all Type 567s S/N 300-up, the +125-volt supply is
adjustable
by
R667
and
R668,
The
—100-volt
supply
must
be
adjusted to the correct voltage before adjusting R668 to
set the +125-volt supply to the correct value.
3-1

Circuit Description—Type 567
+300-Volt Power Supply
A full-wave bridge rectifier circuit from terminals 31 and
32 of T1601 supplies +165 unregulated dc volts that are
added to the unregulated +235 volts (of the +125-volt regu-
lated supply) to provide a total of +400 volts to the +300-
volt regulator and to the ert circuit. A voltage divider
between the regulator output and —100 volts, supplies a
voltage near ground to the grid of V684. If the output
voltage from the regulator changes, a portion of this change
is applied through the divider and C694 to the grid of error
amplifier V684. The error signal is amplified and inverted
and applied to the grid of series regulator V627B. The
change in voltage at V627B grid changes V627B conduction
and compensates for the change in output voltage.
The screen supply for V684 is obtained from both the
+400-volt unregulated lead and from the regulated +300
volts. R685 applies ripple voltage from the unregulated
lead as a signal to V684 screen to help reduce ripple volt-
age appearing in the regulated output.
Capacitor C694 supplies fast changes in output voltage
to the grid of error amplifier V684, reducing the ac output
impedance of the regulator circuit. C676B also aids to
reduce the ac impedance of the +300-volt supply.
On all Type 567s S/N 300-up, the +300-volt power supply
is adjustable by R696 and R698. Both the —100- and +125-
volt power supplies must be adjusted before calibrating R698,
—12.2-Volt Power Supply
The —12.2-volt regulator is similar to the —100-volt
regulator except that it uses transistors instead of tubes.
A full-wave rectifier consisting of D632A and B provides
unregulated de voltage to the regulator. A divider be-
tween —100 volts and ground is used to provide a constant
—12 volts for the base of Q634. The output voltage of the
regulator, appearing at the emitter of Q634, is compared to
the voltage at the base. Because of this circuit arrange-
ment, the voltage at the base of @634 sets the output volt-
age of the supply.
Normally, the voltage at the emitter and base of Q634
will be nearly the same. If the voltage at the emitter
changes because of a change in the supply output voltage,
this changes the current through the transistor. This in turn
produces a change in the collector voltage of @634 and
in the base voltage of Q644. The change at the base of
Q644 is amplified at the collector and applied to the base
of the series regulator transistor Q647. The change in base
voltage of Q647 changes the voltage drop across Q647 in
such a direction as to compensate for the change in output
voltage, and the output then returns to normal.
As an example, if the output of the supply starts to go
more negative, this causes Q634 to conduct more heavily.
This produces a drop in the voltage at the collector of Q634
and at the base of @644. The drop in voltage at the base
of Q644 also causes this transistor to conduct more heavily,
causing its collector voltage to change in the positive direc-
tion, The more positive voltage at the base of Q647 in-
creases the voltage drop across Q647, thereby decreasing
the output voltage of the supply to normal.
3-2
Fuse F647 is used to protect Q647 in the event the output
is accidentally overloaded. Capacitor C646 reduces ripple
voltage at the output of the regulator circuit.
On all Type 567s S/N 300-up, the —12.2-volt supply is
adjustable by R630, R631, and R632. Both the —100- and
+125-volt power supplies must be adjusted before calibrat-
ing R631.
+20-Volt Power Supply
Full-wave bridge rectifier D652A, B, C, and D rectifies
voltage from terminals 11 and 12 of 1601 and _ supplies
power to the +20-volt regulator circuit. A voltage divider
between +125 volts and ground sets the base of Q654 near
+20 volts. The output voltage of the supply, appearing at
the emitter of Q654, is compared to the voltage at the base.
If the supply voltage changes, the bias and conduction
of Q654 is changed. Supply voltage changes are then ampli-
fied and inverted and applied to the base of emitter-follower
@653. @Q653 provides current gain to the correcting signal
and drives the base of Q657 to change its conduction and
bring the output voltage back to normal. C654 provides a
low ac impedance to Qé654 base, reducing the supply ac
output impedance. C656 and C657 also aid to reduce the
supply ac output impedance.
Fuse F657 protects Q657 in the event the output is ac-
cidentally overloaded.
On all Type 567s S/N 300-up, the +20-valt supply is
adjustable by R650 and R651. R650 is connected between the
—12.2- and the output of the +20-volt supply. Thus, the
—12,2- and +125-volt power supplies must both be adjusted
to the correct voltage before adjusting R650 to set the +20-
volt supply to the correct value.
High-Voltage Power Supply
Unregulated +400 volts from the +300-volt power sup-
ply is applied to the high-voltage oscillator, V800. V800
and its associated circuitry is a modified Hartley oscillator.
C802 and the primary winding of T801 form the tuned circuit
in the plate of V800. The oscillator operates at approximately
35 kc. High-voltage transformer T801 provides the high volt-
ages and heater voltages for the rectifiers.
One secondary winding of T801 and rectifier V822 form
a half-wave rectifier circuit which supplies approximately
—3.3 kv to the cathode of the crt. A separate secondary
winding of T801 and V832 supply a floating negative voltage
for the control grid of the crt.
A voltage divider between the —3.3-kv output of V822
and +300 volts supplies voltage to the focusing grid of the
crt and also applies a sample of the power-supply output
to the high-voltage regulator circuit, Potentiometer R841
sets the high voltage. If the output voltage changes from
this set value, a portion of the change appears at the grid
of V814B as an error signal. The error signal is amplified by
V814B and V814A and applied to the screen grid of the High
Voltage Oscillator V800. The change in screen voltage on
the oscillator causes either an increase or a decrease in
the amplitude of the oscillations. The change in amplitude
of the oscillations is always in a direction to compensate
for the error in the output voltage.

The output voltage from V832 is not regulated directly,
but is regulated indirectly by the operation of the V800
screen grid regulator loop.
Capacitor C842 greatly increases the ac loop gain of
the high-voltage regulator circuit, This permits the regulator
to quickly compensate for rapid changes in the output
voltage.
Crt Circuits
Voltage for the control grid of the crt is obtained from
R834 and R833 at the output of the control grid power supply.
By varying the setting of the INTENSITY control R834, the
voltage at the control grid relative to the cathode can be
changed to provide the desired display brightness. Begin-
ning with S/N 249, neon glow tubes B852-B853 were added.
The bulbs ignite only when the INTENSITY control is fully
counterclockwise. Thus, both the grid and cathode of the
crt are protected from arcing.
Voltage for the focus grid of the crt is obtained from
potentiometer R845. The Astigmatism element receives its
voltage from potentiometer R864. Varying both R845 and
R864 affects the crt spot size.
The presence and intensity of the crt beam is controlled
by signals from each of the three plug-in units used with
the Type 567. The oscilloscope uses deflection unblanking
during the sweep interval. In this method an additional pair
of deflection plates in the crt electron gun deflects the beam
off the screen except during the sweep. When the horizontal
sweep is triggered, the unblanking signal is applied from the
time-base unit through terminal 13 of J21 to one of the
unblanking deflection plates. The unblanking signal then
moves the electron beam rapidly on screen for the duration
of the sweep. The beam is then deflected off screen again
until time for the next sweep.
Chopped mode blanking signals from a multi-trace vertical
plug-in unit are applied through terminal 24 of J11 to the
cathode of the crt. These blanking signals are used to blank
switching transients which result when the plug-in unit is
operated in the chopped mode. Chopped blanking prevents
the chopping transients from being displayed on the crt at
normal intensity.
Intensity brightening of the crt trace by either the digital
unit or a two-sweep time-base unit is accomplished by cou-
pling brightening signals to the reference voltage for the crt
grid-voltage supply. The brightening signal from the digital
unit changes the overall grid supply voltage through terminal
15 of J32. The brightening signal from the two-sweep tim-
ing unit changes the overall grid supply voltage through
terminal 14 of J21. Two diodes, D836 and D837, provide
a low-impedance return for the crt grid circuit, reducing
intensity modulation caused by any normal power-supply
ripple. Diode D835 disconnects +125 volts applied to
terminal 14 of J21 by some plug-in units.
Sharply differentiated blanking pulses from the vertical
sampling unit are applied to the crt cathode through ter-
minal 24 of J11 to turn off the crt beam between sampling
dots. Thus, the crt beam is blanked between dots, avoiding
possible display confusion.
A beam rotator coil around the crt is used to align the
oscilloscope trace with the horizontal graticule markings.
Circuit Description—Type 567
The magnetic field set up by the coil deflects the electron
beam up on one side of the crt and down on the other. 8y
varying the strength and direction of the field with the CRT
BEAM ROTATOR control, the trace can be aligned with the
graticule markings.
Amplitude Calibrator (S/N 2060-up)
The Amplitude Calibrator is a two-frequency signal source
that is crystal controlled at 20kc and rc_time-constant
controlled at approximately 1kc. An astable multivibrator
drives both a divide-by-two bistable multivibrator and a
positive slope differentiator circuit. Square waves of known
amplitude at the front-panel connectors come from the +2
circuit, and positive pretrigger pulses come from the dif-
ferentiator circuit. The +2 circuit clamps off the differen-
tiator every other astable cycle. Thus, the positive pretrigger
pulse is generated approximately Y%, cycle before each
positive portion of the output square wave.
Selection of output frequency is by a front-panel 20 KC-
=1KC toggle switch. The switch is open for 20-kc opera-
tion, but is closed for 1-kc operation. 20-kc operation places
a series-mode 40-kc crystal in the feedback path. 1-kc opera-
tion places a 0.0033 uf capacitor across the crystal, making
feedback capacitive and the frequency rc controlled.
Astable Oscillator. Q900 and Q914 form a common-
emitter astable multivibrator. The regenerative feedback
circuit consists of the common connection of the two transistor
emitters, and the crystal (Y905) from Q900 collector to Q914
base for 20-kc operation, or €904-D904 in parallel with the
crystal for 1-kc operation. D904 is reverse biased (for 20-
kc operation} by the voltage divider R912-R914; thus C904 is
effectively switched out of the circuit. D904 is forward
biased when SW915 connects R915 in parallel with R912, con-
necting C904 tn parallel with Y905. Both circuit conditions
are shown in simplified form in Fig. 3-1.
Fig. 3-la shows the active circuit elements for 20-kc
operation. Note the parallel resistance value with equiva-
lent voltage source for R908 and R909. The +21 volts is the
value of divider voltage when no current is drawn through
either R905 or R906. If either base draws current through
its 20-k resistor, the +21 volts acts as if it has a 16.6-k
source resistance. Fig. 3-1b shows the active circuit elements
for 1-kc operation. D904 is a low resistance when it is
forward biased placing C904 in parallel with Y905.
Fig. 3-2 shows four astable circuit waveforms during
1-kc operation. D904 and C904 are drawn between wave-
forms for study purposes. Note that D904 is forward biased
when @900 collector is positive, but reverse biased when
@900 collector is near ground; C904 receives a charge while
Q900 collector is positive, but loses its charge when Q900
collector is near ground.
A 2-kc operation cycle is as follows: Assume Q900 col-
lector has just gone positive. D904 connects C904 from Q900
collector to Q914 base. Q914 base is taken about 12.6
volts more positive (due to previous C904 18-volt charge)
cutting Q914 off. Q900 collector low resistance connects
C904 between +15 volts and +32.6 volts at the junction of
Q914 base and R905. Q914 base draws no current, so C904
begins to discharge through R905 and Q900 collector. Point
#1 of Fig. 3-2 has just been reached. As Q914 base wave-
3-3

Circuit Description—Type 567
+125
27 k 2R90I
+21¥
Q900 Qo14
3.8 ma Y905
! A\ 40 ke ] To
+ 2
R904 ROI7
5.1 k 91k
= 18 ¥ —
+18 ~ —10¥
—+19¥ +21 v =>
—Ov +0.8y—
(a} 20 KC CIRCUIT
+125
27k<R901
-O0Ov +0.3v—
(b) TKC CIRCUIT
Fig. 3-1. Simplified Amplitude Calibrator astable circuits.
form drops toward +21 volts, Q900 collector voltage is pre-
vented from quite reaching +15.2 volts. The fast drop of
Q914 base waveform and slow rise of Q900 collector wave-
form are due to C904 discharge. As the base of Q914
reaches +22.5 volts (point #2 of Fig. 3-2} Q914 begins
to conduct, adding to the current of common emitter re-
sistor R901. Regenerative action follows immediately as Q914
emitter carries Q900 emitter toward reverse bias. Q900 col-
3-4
lector falls as its emitter is taken negative, disconnecting
D904 from C904. C904 is now connected at one end to
about +1.42 volts through the equivalent resistance of 17.2k
(parallel resistance value of R912 and R915}, and to the
base of Q914 at the other end. The charge on C904 limits
its fall at D904 cathode to about +8 volts because Q914
base begins to draw current when the base reaches +15
volts. The parallel resistance of R912-R915 and the base
current of Q914 recharge C904. As the current through
R912-R915 decreases (nearing point #3 of Fig. 3-2) the cur-
rent through Q914 decreases letting the common emitter
voltage go positive, causing Q900 to again conduct. Q900
conduction begins and its collector rises about 2.5 volts before
D904 again connects the regenerative feedback circuit so
the astable will flip. As D904 conducts, fast regenerative
action turns Q914 off and Q900 on. The cycle is complete
and C904 begins to discharge to repeat the process.
D904 — oe +14.6¥
Cathode
+8
+2¥
0904 cao4
— —— 32.6
ao14 +82.0¥
Base +22.5v
+20v
+15v
—S————=— a — +15.2¥
Q900
Collector
—> +2.5¥
Ov
TN _ _ +21¥
Qgo1l4
Collector
s +0.3¥
4 A &
#1 #2 #3
Fig. 3-2. Astable multivibrator waveforms during 1-kc operation.
A 40-kc operation cycle follows the same sequence of
events, except that Y905 is the feedback element between
Q900 collector and Q914 base and D904 is reverse biased
all the time. Y905 is an open circuit at all frequencies other
than its series resonant frequency of 40 kc. The waveform
at the base of Q914 in Fig. 3-la shows the crystal sine wave
nature when Q914 is cut off. Base current of Q914 flattens
off the waveform bottom as Y905 provides turn-on base cur-
rent during the time Q914 conducts.
Once 40-kc oscillation is established, the crystal assumes
a mechanical vibration at the rate of oscillation. At the time
the operator switches from 20-kc to 1-kc operation the crystal
mechanical vibration is seen to die out during the first few

Q900
Collector
Q914
Base
Q914
Collector
Q955
Base
Q935
Base
D933
Cathode
Q925
Collector
Q935
Collector
Q955
Emitter
+ Pretrigger
D945
Cathode
Fig. 3-3. Amplitude Calibrator time diagram. Operation at 20 ke
(partial graticule shown).
moments of |-kc operation. Actually, the crystal aids in
coupling energy when the astable is operating at 2kc
because the rapid voltage changes at each switching time
contain high frequencies. The crystal then “locks in’ the
2-kc oscillations causing the 1-kc output signal to be very
stable. The actual frequency of 1-kc output cannot be speci-
fied tightly because the crystal’s ability to lock-in 2-kc
oscillations is dependent upon transistor beta and other
variables.
+2 Multivibrator. @925 and Q935 form a triggerable
bistable multivibrator that divides the astable output fre-
quency by two. It drives the output voltage divider and
controls the +Pre Trigger emitter-follower Q955. The time
relationships of several points throughout the whole Ampli-
tude Calibrator are shown in Figs. 3-3 and 3-4. Each figure
is made up of three multiple-exposure photographs made by
externally
triggering
the
test
oscilloscope
to
guarantee
time
coincidence of each waveform; voltage amplitudes are
uncalibrated.
Assume
@Q925
is
conducting
and
is
saturated
so
its
cal-
lector
voltage
is
less
than
a
volt
positive.
Voltage
divider
Circuit Description—Type 567
R925-R937
from
@925
collector
to
Q935
base
sets
Q935
base
at
about
—1.5
volts,
assuring
that
Q935
is
completely
cut
off.
D935
in
Q935
collector
circuit
permits
the
output
voltage
divider
to
disconnect
from
R934-R935.
D935
anode
voltage
is
about
+5.5
volts
and
its cathode
and
Q935
collector
are
at
about
+20.2
volts.
Q935
collector
voltage
is
set
by
the
output
voltage
divider.
Thus,
D935
assures
that
the
output
voltage
divider
will
not
be
loaded
by
the
-+2
circuit
during
the
positive
portion
of
the
output
signal.
The
output
voltage
is
adjusted
by
R943,
and
is
completely
independent
of the
+2
circuit.
Q925 conduction draws current through both its normal
collector load R924, and through R952-D953-D954-R954_ to
bias
D951
and
Q955
to
cutoff.
When
D951
is
cut
off,
Q955
cannot receive positive pulses from the astable circuit.
The
+2
multivibrator
switches
states
whenever
the
astable
output
goes
negative.
R922
holds
D923
cathode
slightly
negative
in
respect
to
its
anode,
but
not
conducting.
As
the
astable output
goes
negative,
C923
couples
a
turn-off
pulse
through
D923
to
the
base
of
Q925.
(D933
was
held
about
7
volts
reverse
biased
with
Q935
cut
off.)
As
Q925
starts
Q900
Collector
Qo14
Base
Q914
Collector
Q955
Base
Q935
Base
D933
Cathode
Q925
Collector
Q935
Collector
Q955
Emitter
+ Pretrigger
D945
Cathode
Fig. 3-4. Amplitude Calibrator time diagram. Operation at 1 kc
(partial graticule shown).
3-5

Circuit Description—Type 567
to turn off, its collector voltage rises positive, C925 applies
turn-on bias to Q935 base and the +2 circuit switches.
Regenerative feedback is applied to Q925 base by Q935
collector and C935.
Q935 collector now rests at less than +0.2 volt, close
enough to ground that D945 of the output divider carries
no current. Q935 collector current passes through both its
normal collector load R934 and the series resistance of
R940-R941-R943.
Q925 is cut off and its collector rests at +5 volts. The
+2 circuit will change states the next time the astable output
goes negative and the cycle will repeat.
+Pre Trigger circuit. The +Pre Trigger circuit is an
emitter-follower and differentiator circuit that responses to
positive signals from the astable circuit if Q925 is cut off.
When Q925 is conducting, D951 anode is held at about +1.5
volts preventing any positive signal from being applied to
the base of Q955. Thus it is that a +Pre Trigger pulse is
formed only when the output signal is at ground and Q925
is cut off. D954 allows Q925 collector to rise for rapid
switching of the +2 circuit, C954 serves as a low impedance
so any stored charge in D954 will not be applied to Q955
base. C954 also releases Q955 base slowly as R954 charges
C954 so Q925 positive change does not reach Q955 base as
a signal. D953 disconnects C954 from Q955 base so signals
can couple through D951 and turn on the emitter-follower.
Q955 emitter faithfully follows every other positive astable
output pulse. C957 differentiates Q955 emitter signal and
D959 couples only the positive pulse to the output. Any
negative change at Q955 emitter, from either the astable
signal drop or from Q925 collector pulling down, is stopped
from reaching the output by D959.
Amplitude Calibrator (S/N 101-299)
The calibrator consists of a bistable multivibrator, V884A
and V884B, which is triggered at the line frequency by
a 6.3-volt ac signal applied to the cathode of V884A. The
signal at the cathode of V884A switches the multivibrator
between its two states. When V884A is conducting, the low
voltage at its plate cuts off V884B. Or, when V884B is
conducting, its low plate voltage lowers the grid voltage
of V884A sufficiently to cut V884A off. Thus, both tubes do
not conduct at the same time.
When V884A is cut off, the voltage at the control grid
and cathode of V884B is determined by the setting of the
CAL AMPL control, R871. This determines the maximum
voltage level reached by the square-wave output. The
square waves start at ground at the time V884B is cut off
and reach the maximum amplitude established by R871
when V884A is cut off. The CAL AMPL control is adjusted
to give the appropriate output square-wave amplitudes via
the output divider R885 through R889.
Amplitude Calibrator (S/N 300-2049)
R890 was added at S/N 300 so the 0.5 output jack will
provide a 100-mv peak-to-peak signal into 50 ohms. No
other alterations were made and the circuit description is
the same as above.

SECTION 4
MAINTENANCE
Visual Inspection
If trouble occurs in the Type 567, make sure the associated
equipment is operating and the controls are properly set.
If it is determined that the trouble is definitely in the Type
567, a visual check may reveal the cause. Defects such as
loose or broken connections, frayed or broken cables, dam-
aged connectors, and burned components can generally be
detected by a visual inspection. Except for heat-damaged
components the remedy for such defects is obvious. Over-
heating of components is usually a symptom of other, less
apparent troubles in the circuit. For this reason, it is essen-
tial to determine the actual cause of overheating before the
damaged parts are replaced; otherwise, the damage may be
repeated.
Parts Removal and Replacement
Whenever a part is replaced, check and adjust the instru-
ment calibration as necessary. Most parts in the Type 567
can be replaced without detailed instructions. Some, how-
ever, are best removed and replaced by using definite pro-
cedures contained in the following paragraphs. (Parts order-
ing information is included in the Parts List section of this
manual.}
CAUTION
Turn ac power off before removing tubes or transis-
tors from their sockets.
Transistor Replacement. Transistors should not be re-
placed unless they are actually defective. Transistor defects
usually take the form of the transistor opening, shorting, or
developing excessive leakage. To check a transistor for
these and other defects, use a transistor curve display instru-
ment such as a Tektronix Type 575. However, if a good
transistor checker is not readily available, a defective
NPN or PNP
TRANSISTOR
Emitter-to-
Collector Voltage
Emitter-to-Base
Voltage
Fig. 4-1. In-circuit voltage checks NPN or PNP transistors.
transistor can be found by signal-tracing, by making in-
circuit voltage checks, by measuring the transistor forward-
to-back resistance using proper ohmmeter resistances, or
by using the substitution method. The location of all transis-
tors is silk-screened on the chassis next to each socket.
To check transistors using a voltmeter, measure the emitter-
to-base and emitter-to-collector voltages and determine if the
voltages are consistent with the normal resistances and
currents in the circuit (see Fig. 4-1).
To check a transistor using an ohmmeter, know your ohm-
meter ranges, the currents they deliver, and the internal
battery voltage(s). !f your ohmmeter does not have suffi-
cient resistance in series with its internal voltage source, ex-
cessive current will flow through the transistor under test.
Excessive current and/or high internal ohmmeter source
voltage may permanently damage the transistor.
NOTE
As a general rule, use the RX 1k range where the
current is usually limited to less than 2ma and
the internal voltage is usually 14% volts. You can
quickly check the current and voltage by insert-
ing a multimeter between the ohmmeter leads and
measuring the current and voltage for the range
you intend to use.
When you know which ohmmeter ranges will not harm
the
transistor,
then
use
those
ranges
to
measure
the
resistance
with the ohmmeter connected both ways as given in Table
4-1,
TABLE 4-1
Transistor Resistance Checks
Ohmmeter
Connections!
Resistance Readings That Can Be
Expected Using the R X 1k Range
Emitter-Collector
to around 500 k}.
High reading one way (about 200 k or
more}. Low reading the other way
(about 4002 to 2.5k).
High reading one way (about 500 k or
more). Low reading the other way
{about 4002 to 25k).
Emitter-Base
Base-Collector
lTest prods from the ohmmeter are first connected one way to the
transistor leads and then the test prods are reversed (connected
the other way). Thus, the effects of the polarity reversal of the
voltage applied from the ohmmeter to the transistor can be observed.
'f there is doubt about whether the transistor is good
or not, substitute a new transistor, but first be certain the
circuit voltages applied to the transistor are correct before
making the substitution.
When checking transistors by substitution, be sure that
the voltages and loads on the transistor are normal before
making the substitution. If a transistor is substituted without
first checking out the circuit, the new transistor may im-
mediately be damaged by some defect in the circuit.
4-1

Maintenance—Type 567
Tube Replacement. Tester checks on tubes used in the
Type 567 are not recommended. Tube testers sometimes
indicate a tube to be defective when that tube is operating
satisfactorily in a circuit, or they may fail to indicate tube
defects which affect the performance of the circuits. The
criterion for the usability of a tube is whether or not it
works properly in the circuit. If it does not, it should be
replaced. Unnecessary replacement is not only expensive
but may also require needless recalibration of the instrument.
Lamp Replacement. The graticule illumination lamps are
bayonet Type 44, 6-8 volt bulbs. Remove the four bezel
nuts, lift away the bezel and graticule eyebrow, and replace
the lamps in the normal manner.
Air Filter
The Type 567 Oscilloscope is cooled by air drawn through
a plastic disposable filter located at the rear of the instru-
ment. If the filter becomes excessively dirty, it will restrict
the flow of air and may cause overheating. High internal
temperatures will not only reduce the lifetime of the instru-
ment components, but may also cause the thermal cutout
to open at inconvenient times. If the oscilloscope is wired
for 117 volts, the fan motor continues to run when the
thermal cutout opens but all other power in the instrument
is disconnected. If the instrument is wired for 234 volts, all
power in the instrument including the fan is disconnected
when the cutout opens. Any time that the thermal cutout
opens, the filter should be checked immediately. When the
interior temperature of the instrument has returned to the safe
level, the thermal cutout will close to reapply power to the
instrument.
The filter should be visually checked every few weeks.
It should be replaced at least every three or four months,
and more often if required.
Fan Motor
Fan motor bearings have been lubricated at the factory
and should not require further lubrication more often than
about every six months. One or two drops of light machine
oil on the bearings is adequate.
Removal of Panels
The side, top, and bottom panels of the Type 567 can be
removed separately for maintenance work. All panels are
held in place by small coin-slot fasteners. To remove the
panels, use a screwdriver or coin to rotate the fastener
approximately two turns counterclockwise. Pull the upper
portion of the side panels outward from the top. After first
releasing the fasteners, the top and bottom panels can be
lifted off. Panels can be replaced by reversing the order
of their removal.
Cleaning
The Type 567 should be cleaned as often as operating
conditions require. Accumulation of dirt in the instrument
can cause overheating and component breakdown. Dirt on
components acts as an insulating blanket and prevents effi-
cient heat dissipation. It also provides a possible electrical
conduction path.
4-2
Loose dust accumulated on the outside of the Type 567
can be removed with a cloth or small paint brush. The paint
brush is particularly useful for dislodging dust on and
around the front-panel controls. Dirt which remains can be
removed with a soft cloth dampened in a mild solution of
water and detergent. Abrasive cleaners should not be used.
The high-voltage circuits, including parts located under the
high-voltage shield, should receive special attention. Ex-
cessive dust and dirt in these areas may cause high-voltage
arcing and result in improper instrument operation.
CAUTION
Avoid the use of chemical cleaning agents which
might damage the plastics used in this instrument.
Some chemicals to avoid are benzene, toluene,
zylene, acetone, or similar solvents.
To clean the crt protector plate and the face of the crt,
first remove the four bezel mounting nuts. Then, remove the
bezel and the protector plate. Clean all surfaces with a soft,
lint-free cloth dampened with mild detergent and water.
Repeat with a cloth dampened with water only.
Recalibration
To assure accurate measurements check the calibration of
this instrument after each 500 hours of operation or every
six months if used intermittently. Complete calibration
instructions are given in Section 5.
The calibration procedure can also be helpful in localizing
certain troubles in the instrument. In some cases, minor
troubles, not apparent during normal use, may be revealed
and/or corrected by recalibration.
Resistor Coding
The Type 567 uses a number of very stable metal film
resistors identified by their gray background color and color
coding.
If the resistor has three significant figures with a multiplier,
the resistor will be EIA color coded. If it has four significant
figures with a multiplier, the value will be printed on the
resistor. For example, a 333-k resistor will be color coded,
but a 333.5-k resistor will have its value printed on the
resistor body.
The color-coding sequence is shown in Fig. 4-2, and Table
4-2.
e— Ist Sig. Fig.
2nd Sig. Fig.
3rd Sig. Fig.
Multiplier
Tolerance
Date Code
Fig. 4-2. Standard EIA color code for metal film resistors.