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PS163
DUAL TRACE
TRIGGERED SWEEP
OSCILLOSCOPE
SENCORE
SERVICE
MANUAL
"t h e a ll a me r ica n li ne”
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TABLE OF CONTENTS
SERVICE MANUAL
TABLE OF CONTENTS
CIRCUIT DESCRIPTION
SYNC OR TRIGGER CIRCUIT
TIME BASE GENERATOR
TIME BASE CONTROL CIRCUITS
PREAMPLIFIERS
VERTICAL INPUT (Switch and Display Board)
OUTPUT AMPLIFIER (Horizontal and Vertical)
HV SUPPLY and DC Coupled CRT Unblanking Circuit
LV SUPPLY
DISASSEMBLY INSTRUCTIONS
CASE
CRT
CALIBRATION
PS163
PREAMPLIFIERS Channel A & B
DC Balance
Calibration
Attenuator Frequency Compensation
TIME BASE
Stability
Differential Comparitor Balance
Sweep Speed and Sweep Width
5X Expand and Position Vernier
Sync Separator Balance Adjustment
Blanking Level an d Output Stage Collector Voltage Adjustment
Cal Volts 2V PP
CRT Tilt Adjustment
SERVICE PROCEDURES
TROUBLE CHARTS
BOARD LAYOUTS AND TABLES
Time Ba se
Output
Pre Amp
Display
LV Supply
HV Supply
SAFETY REMINDER
WARRANTY STATEMENT
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CIRCUIT DESCRIPTION
SYNC or TRIGGER CIRCUITS
The HORIZONTAL SYNC pushbutton switch selects
the source of the sync signal. The output of the
HORIZONTAL SYNC switch is AC coupled through
C200 to the input protection circuit comprised of
CR201 and CR202 an d associated components. C203,
CR200, and R200 act as a filter to remove high fre
quency noise that would otherwise result in unstable
sync in the DUAL CHOPPED mode. SW200A
then connects the sync signal to either the sync se
parator (TR200-TR203) for the TV Vertical and TV
Horizontal sweep positions, or directly to the input
of the differential comparitor (TR205-TR212).
The SYNC POLARITY switch (SW2) selects which in
put of the sync separator or differential comparitor
will receive the sync signal, or the reference voltage
from the SYNC LEVEL control (R7).
Both the sync separator and the differential com
paritor are balanced differential amplifiers, and there
fore will accept a signa l to either input. The balanced
amplifier, in the sync separator section, has just
enough gai n to reliably operate the sync separa tor
transistor (TR204). The sync separator transistor
(TR204) is biased so that only the pea ks of the incom
ing signal will cause it to conduct producing an output
signal at its collector load resistor (R222). The output
of TR204 goes to both a differentiating network
(C211 and R227) and to an intergrating network
(C213, C214 and R226). SW200C selects and couples
the output of the integrating network for the TV
Vertical sweep position or the output of the dif
ferentiating network for the T.V. Horizontal sweep.
The HORIZONTAL SWEEP push button (SW3) switch
is designed so when in the manual triggered mode, the
sync level control is connected to the reference input
of the differential comparitor. While in the AUTO
TRIGGERED and the FREE RUNNING modes the
reference side of the comparitor is connected to
ground. The differential comparitor is a very high
gain differential amplifier, so even a relatively small
input signal will cause TR212 to change from satura
tion to cutoff, resulting in a 25 volt signal to drive the
Schmitt trigger. The Schmitt trigger (TR213 and TR
214) is designed so with no input signal, TR214 is in
the on state with the voltage at the emitters of both
transistors at approximately plus 10 volts. As soon as
the input signa l to the bas e of TR213 exceeds the
10 volt level at its emitter TR213 starts to con
duct. When TR213 start s to conduct, two thing s
happen. First, the voltage ac ross the common emitter
resistor R254 starts to rise, and second, the voltage at
the collector of TR213 starts to drop. TR214 then
rapidly changes to its off state as a result of the com
bination of a positive signal on its emitter, and a neg
ative signal on its base. Thus the output of the Sch
mitt trigger coupled through C219 to the base of TR
218 is a fast (lOnSec) pulse regardless of what the
signal to the input of the trigger circuit was.
TIME BASE GENERATOR
The “heart” of the PS163 is the time base generator,
and its function is to provide an extremely linear
ramp (sawtooth) for use as a horizontal sweep signal.
The PS163 accomplishes this by u sing a constant
current source to char ge the timing capacitor (C285 -
C238). The constant current source is provided by
TR227. TR228 is used as a diode for temperature
compensation. The base and therefore the emitter
voltage for TR227 is determined by the voltage
divider R286 - R289. With the emitter voltage of
TR227 constant, the output current will remain
at a constant value determined by the 1% resistors
R290 - R301. SW200F selects the valu e of timing
capacitor, and SW200G selects the value of constant
current resistor. R288 is the front panel horizontal
frequency vernier and is controlled by the small center
knob on the TIME BASE - FREQUENCY switch.
R288 must be fully clockwise to' maintain time base
calibration.
TR218 and TR219 form a Schmitt trigger with
TR218 held in the off condition by the negative
voltage from the stability control R267. The on
condition of TR219 is directly coupled by the emit
ter follower transistor TR220 producing a negative
voltage at the base of TR223 holding it in the on
condition. The on condition of TR233 shunts the
timing capacitor, therefore producing no sweep signal.
When a positive trigger pulse is applied to the base of
TR218, it, TR219, TR220, and TR221 instantly
chan ge states. The positive voltage coupled to the
base of TR223 causes TR223 to stop shunting the
output of the constant current source . The output of
the constant current source now starts charging the
timing capacitor, producing a very linear negative
going ramp. The negative ramp is coupled through
the high impedance source follower TR229, and am
plified by TR230. The negative ramp at the junction
of R303 and R304 is coupled back to the base of
TR218 through TR226, CR209 and R269, and also
charges one of the hold off capacitors selected by
SW200E. As soon as the negative ramp at the ba se
of TR218 reaches the lower trip point of the Schmitt
trigger, TR218 and TR219 will again change states,
with TR219 returning to the on condition. The on
condition of TR219 will turn on TR223, returning
the voltage on the timing capacitor to zero, and caus
ing the beam to retrace on the CRT. The voltage
stored on the hold off capacitors, C231 - C234, keeps
the base of TR218 negative long enough for all circ uits
to reset in preparation for the next trigger pulse .
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TR224 and TR225 serve no active purpose in the
circuit and are only used to kill all output from the
time base when using the VECTOR INPUT, 60Hz or
EXT sweep features. The emitter follower TR231
provides an isolated output of the sawtooth for the
jack on the rear of the PS163.
The square wave at the emitters of TR220 and TR221
is used to drive the CRT unblanking circuit and the
Display board in the alternate sweep mode.
TIME BASE CONT ROL
CIRCUITS
The control circuit for the time base generator con
sists of TR215, TR216, and TR217.
In the MANUAL TRIGGERED mode, the base of
TR217 is grounded by the HORIZONTAL SWEEP
push button switch SW3A. With the base of TR217
grounded, TR217 will be off, and will have no effect
on the negative voltage applied to the base of TR218
through the stability control. The stability control
has been adjusted so that TR218 will only conduct
when it receives a proper trigger pulse from the trigger
circuit. There will be no sawtooth sweep produced
until the trigger circuit is adjusted to provide a proper
trigger pulse.
In the FREE RUNNING mode, the base of TR216 is
grounded by SW3C. The base of TR217 is ungrounded
because of the mechanical interlock of SW3. Ground
ing the ba se of TR216 causes the transistor to turn
off, raising the collector voltage to the positive 15
volt level. This positive voltage is coupled through
R262, R263 and TR217 to the junction of R265 and
R266, which changes the voltage on the stability con
trol enough so that TR218 will conduct as soon as
the hold off capacitor has discha rged. The time base
generator will now free run, but it will be sensitive to
trigger pu lses coupled into the base of TR218 during
the time that it take s for the hold off capacitor to dis
charge .
In the AUTO TRIGGERED mode, the base of TR216,
is grounded through resistor R259, and with no trigger
pulses, the action is the sam e as in the FREE RUNN
ING mode. If trigger pulses are present, they will be
coupled to the base of TR215 through C220. The
trigger pulses will be amplified by TR215 and coupled
to CR205. CR205 will detect the trigger pulses, pro
ducing a positive voltage at the base of TR216, caus
ing it to conduct. Its collector voltage will drop,
cutting off TR217, and allowing the stability control
to return to the sa me negative voltage a s in the
MANUAL TRIGGERED MODE. C222 is used to
hold the base of TR217 negative between trigger
pulses. In this mode the time base will free run in the
absence of trigger pulses. The presence of trigger
pulses will ca use the time base to automatically
switch to a triggered mode.
TR233 and TR234 amplify the horizontal sweep signal,
and together with constant current source TR232,
establish the push-pul l signal necessary to drive the
output amplifier. R l l is the front panel horizontal
position control. R317 adjusts the gain of TR233
and TR234 to produce a horizontal trace 11cm long.
SW5 is a push-pull switch mounted on the rear of the
HORIZONTAL POSITION control. When the shaft
is pulled to its out position, the switch connects R319
in parallel with R317. R319 is adjusted for 5X in
cre ase in the gain of TR233 and TR234. R321 and
R322 are ganged together, and are used to match the
horizontal position of the expanded sweep to that of
the normal sweep.
TR235 a nd TR236 are used in the EXT horizontal and
60Hz sweep positions to amplify the incoming signal.
The output of TR235 is coupled through SW200H
to the base of TR233. R331 is the front panel hor
izontal gain control (small center knob on TIME
BASE - FREQUENCY), and R8 (front panel LINE
SWEEP PHASE) is used to adjust the pha se of the
60Hz sweep.
PREAMPLIFIERS
Both of these amplifiers are identical, so we will look
only at the operation of the CHANNEL A pre
amplifier. The signal at the front panel input is
coupled to the input of the preamp through the IN
PUT COUPLING switch. When this switch is in the DC
coupled position, the input signal is direct coupled
to the input of the pre amp through R4, the 47 ohm
resistor. In the AC position, the signal is AC coupled
to the input of the preamp through C2 and R4. In the
ground position, the input sig nal is grounded through
R3 (10K) and C2, while the input of the preamp is
tied to ground through R4.
Once inside the preamp, the input signal must be att
enuated to a level that will not over drive the FET in
puts. The attenuation ratios are: 1:1, 10:1, 100:1
and 1,000:1, and are selected by SW100A and SW
100B . In order to maintain exact attenuation at
higher frequencies, the 1,000:1 attenuator section is
actually a 10:1 and a 100:1 connected in series. The
capacitors in the attenuator are used for frequency
compensation. The input FET TR100 is connected as
a source follower to match the 1 meg input imped
ance to the low impedance transistor circuitry, and is
protected by CR100 and CR101 which clamp the in
put to plus and minu s 2 volts. TR101 along with the
DC BALANCE control R120 provide a DC reference
for the balanced differential amplifiers that follow.
TR103A and TR103B along with constant current
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source TR104 produce the necessa ry push-pull si gnal
for deflection.
TR103A in cascode with TR105 is actually the first
stage of voltage amplification. SW100C selects dif
ferent values of emitter resistors for TR103 to change
the gai n of this stage in the 1,2,5 sequen ce necessa ry
to produce the full ran ge of input sensitivities of the
preamp. TR108 operates as a current amplifier to
drive the low impedance input of the output amplifier
and in addition it changes the DC level of the signal.
R156 is the front panel vertical gain vernier, and is
controlled by the small center knob of the PPV PER
DIV. switch. R156 must be fully clockwise to main
tain calibration of the preamplifier. R5 and R6 are a
dua l control used as the front panel TRACE POSITION
control.
VERTICAL INPUT
(Switch a nd Di spl ay Boa rd)
The actual switching of either CHANNEL A or
CHANNEL B to the vertical output amplifier is ac
complished by diodes CR403 - CR410. If a positive
voltage is applied to the junction of CR404 and CR
405, they will be reverse bias ed, and therefore have no
effect on the signal from CHANNEL A. CR403 and
CR406 will then be forward biased by the difference
in DC voltage level between the preamp and the out
put amplifier, and the signal from CHANNEL A will
be coupled to the vertical output amp. If a negative
voltage is applied to the junction of CR404 and CR
405, they will be forward biased, and the signal
from CHANNEL A will be shunted to ground through
TR403. CR403 and CR406 would then be reverse
biase d by the negative voltage on their anodes, block
ing the CHANNEL A sign al from reaching the output
amplifier. Multivibrator TR404 and TR405, along
with emitter followers TR403 and TR406 are con
structed so that if a negative voltage is applied to the
junction of CR404 and CR405 from the emitter of
TR403, then a positive voltage will be applied to the
junction of CR408 and CR409 from the emitter of
TR406. With a positive voltage at the junction of CR
408 and CR409, they will be reversed biased, while
CR407 and CR410 will be forward biased, connect
ing the output of the CHANNEL B preamp to the
vertical output amp.
Pushing the CHANNEL A VERTICAL INPUT button
shorts the base and emitter of TR404 resulting in a
positive voltage at its collector. This positive voltage
is coupled through emitter follower TR403 to the
junction of CR404 and CR405, connecting the
CHANNEL A preamp to the vertical output amp.
is coupled through emitter follower TR406 to the
junction of CR408 and CR409, connecting the output
of the CHANNEL B preamp to the vertical output
amplifier.
Pushing the DUAL ALTERNATE VERTICAL INPUT
button connects the blanking waveform from the
junction of the emitters of TR220 and TR221 on the
time base board to the base of TR407. During the re
trace time of the sweep, a negative pulse will be
coupled to the ba se of TR407 turning it on. When
TR407 turns on, it will sh unt the minus 25 volt supply
for the multivibrator to ground. With the emitters of
TR405 and TR404 shorted together, by the normally
closed contacts of the DUAL CHOPPED VERTICAL
INPUT switch, the multivibrator is wired a s a bistable
that will switch states every time the minus 25 volts is
removed. Therefore every time the sawtooth from the
time ba se retraces, the multivibrator will change stat es
producing an alternate connection of the CHANNEL
A and CHANNEL B preamps to the vertical output
amplifiers.
Pushing the DUAL CHOPPED VERTICAL INPUT
button removes the short between the emitters of TR
403 and TR404, an d applies power to the multi
vibrator at the junction of R419 and R420. The mult
ivibrator will now free run at approximately lOOKHz,
with the result that CHANNEL A and CHANNEL B
preamps will be switched to the vertical output amp
lifier during alternate half cycles of the lOOKHz
chopping frequency. Plus 15 volts is connected by
the remaining pair of contacts to R200 on the time
base board, activating the low pass filter at the input
of the trigger circuit.
Pus hing the VECTOR VERTICAL INPUT button does
the following: switches the output of the time base
board from the horizontal output amplifier to ground ,
connects the CHANNEL B preamp to the horizontal
output amplifier, applies minus 25 volts to R284 on
the timebase board stopping the operation of the
timebase generator, and shorts base to emitter of TR
404 connecting the CHANNEL A preamp to the vert
ical amplifier.
The display board also contains the circuit for the 2
volt square wave calibrator. TR400 and TR401 form
a free r unning multivibrator operating at approximately
lKHz. TR402 is a squaring amplifier to improve the
rise time of the square wave. R409 is an internal con
trol to set the level of the 2 volt output.
OUTPUT AMPLIFIERS
(Hori zontal a nd Vertical)
Pushing the CHANNEL B VERTICAL INPUT button
sho rts the ba se and emitter of TR405 resulting in a
positive voltage at its collector. This positive voltage
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The horizontal and vertical output amplifiers are id
entical in the way that they process the incoming
signal. The only difference is that the horizontal amp
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has 25% more gain to compensate for the lower sen
sitivity of the horizontal deflection plates in the CRT.
TR500 and TR501 provide a low impedance termina
tion for the input of the output amplifier, and are
actually in cascode with the last sta ge of the preamp
or time base. R504 and R505 ar e the collector
load resistors for this cascode stag e. R500 is found
only on the vertical output amplifier, and is used to
reduce the gain of the cascode stage, to partially com
pensate for the higher sensitivity of the vertical de
flection plates. TR502 and TR503 are emitter fol
lowers to provide a low impedance drive for the out
put sta ge. TR504 in cascode with TR506 along with
TR505 in cascode with TR507 form the output volt
age amplifier sta ge. TR508 and TR509 form a con
stant current source to prevent the output stage from
saturating, even if overdriven. R 501 is found only in
the horizontal output amplifier, and is used to in
crease the gain to partially compensate for the lower
sensitivity of the horizontal deflection plat es. Access
to the vertical deflection plates is available through
VERT. DEF. PLATES jacks with R ll and R12 used
to isolate the vertical output amplifier from the ex
ternal signal.
SW5 is the VERT DEF PLATES switch and connects
the external signal to the deflection plates in the EXT
position, and the vertical output amplifier to the
pla tes in the NORMAL position. This switch should
be in the NORMAL position for normal operation.
HV POW ER SUPPLY
an d DC Co up led
CRT U nb la n kin g Circuit
The PS163 incorporates a 2000 volt high voltage
power supply with advanced design, normally found
only in much higher priced equipment. Instead of a 60
Hz supply with all the inherent problems of high volt
age breakdown and large physical size, the PS163 uses a
Hartley oscillator supply operating at 30KHz. The
small physical size of the 30KHz transformer and
capac itors results in a considerable savings in weight,
along with an increase in reliability. TR602 and the
primary of the high voltage transformer T600 are the
active components of the oscillator. C604 is used to
reson ate the primary of the transformer to 30KHz.
Feedback to sus tain oscillation is provided by the
small section of the primary winding below the center
tap. R609, the 3K resistor, is only used to start the
oscillation.
The high voltage transformer is equipped with two
secondary windings, one to supply voltage to the cath
ode of the CRT, and one to provide voltage to the
control grid of the CRT. The two windings are isolated
from each other and from ground, so that the direct
coupled CRT unblanking signal may be applied to the
low side of the control grid secondary. The unblank
ing signal is coupled from the junction of the emitters
of TR220 and TR221 on the time base board to the
emitter of TR600. This sign al is positive when the
time base is producing a sweep, and negative when the
time base is in the hold off condition.
As soon as the time base starts to sweep, and a pos
itive voltage is coupled to the emitter of TR600, TR
600 will go to the off state. With TR600 off, its
collector voltage will go to plus 75 volts, turning on
TR601, and placing plus 75 volts on the emitter of
TR601. The positive 75 volts change at the emitter
of the TR601 will be coupled by R604 - R608 and
R608 and C602 to the control grid of the CRT, caus
ing the CRT to conduct producing a trace on the
screen. R604 is adjusted to provide just enough neg
ative voltage to the grid of the CRT so the CRT will be
turned off in the absenc e of the unblanking voltage at
the emitter of TR600.
With a negative signal applied to the emitter of TR
600, it will be in the on condition, resulting in zero
voltage at the collector. This voltage will also be pre
sent at the b ase of TR601, cau sing TR601 to be in the
off condition. With TR601 in the off condition, its
emitter voltage will be near zero determined by the
forward bias condition of CR603. This voltage is
coupled to the CRT grid holding it in cutoff.
The cathode voltage on the CRT is adjusted by the in
tensity control R13 to provide manual control of the
trace brightne ss. The focus control, R15, is in the
same voltage divider as the intensity control so as
the intensity control is varied, the focus voltage will
follow it. The result is the CRT beam remains focused
at any intensity setting.
Provision for Z axis modulation is provided by C6
coupling into the cathode of the CRT. With this input,
a positive signal will decrease the brightness of the
trace, and a negative signal will increase the bright
ness of the trace. SW8, the Z AXIS input switch, is
used to connect the Z AXIS jack to the cathode when
this input is desired. This switch should be in the off
position for normal scope operation.
LO W VO LTA GE POW ER
SUPPLY
The PS163 low voltage power supply incorporates a
ferroresonant power transformer (T l), and full wave
rectification, to provide regulated voltage outputs of
pl us 200 volts, plus 75 volts, plus 25 volts, plus 15
volts and minus 25 volts. The blue/white, blue/white
winding of T l is resonated by capacitor C7 to the 60Hz
power line frequency. Because of the energy stored in
this parallel resonant circuit, the output voltage of T l
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will remain constant over a wide range of input volt
age variations, and load current variations.
TR700 - TR702 are electronic ripple filters with a
filtering action equal to the beta of the transistor
times the capacitor from base to ground. These tran
sis tors are not protected against a shorted output, so
care should be taken when working inside the PS163
not to short the plus 25, plus 15 or minus 25 volt
DISASSEMBLY INSTRUCTIONS
CASE
supplies to ground. If thes e transistors ar e defective
they may not affect the output voltage from the
supplies, but will cause an increase in the ripple on the
supply lines.
R19, the ASTIGMATISM control on the back panel,
is used in conjunction with the FOCUS control to ad
just the sharp ness of the trace.
The case of the PS163 is in two parts. The first sec
tion is the top and side wrap. Remove the 4 philips
head screws from the top of the cas e, and the 5 philips
head screws from each side of the cas e. Slide the wrap
about lA inch forward, and lift it up and off. The
next section is the bottom and rear cover. Remove
the three philips hea d screws holding the cord wrapper
on the back of the PS163. Place the PS163 face
down on a soft cloth and remove the two philips
screws from the aluminum trim bar along the front
edge of the bottom. Remove the remaining philips
head scre ws from the bottom of the case, and lift the
case straight up being careful not to damage the cir
cuit breaker or astigmatism control. Reverse this pro
cedure for reassembly.
CRT
Place the PS163 face down on a soft cloth and re
move the philips screw that secures the rear support
bracket for the CRT from the under side of the
CALIBRATION
chassis. Return the PS163 to its normal up-right
position. Remove the four philips screws that secure
the bottom edge of the output amplifiers from the
rear of the chassis. Remove the two screws that hold
the output amplifier support bracket from the top of
the ch assis. Remove the socket from the rear of the
CRT. Remove the 4 bezel nuts, the bezel, the green
filter, and the grid graticule from the front of the
PS163. Remove the 4 black plastic light shields, and
note that there ar e two different types of shields. The
sh ields in the upper right and lower left have the open
ing in front of the collar, and are used to illuminate
the grid graticule. Remove the vector graticule , and
note the 4 philips screws that are recesse d behind it.
Carefully remove these 4 screws while holding the
CRT. After the 4 screws are removed, push the CRT
to the rear, and swing it out toward the open side of
the chassis. Be sure that the front support bracke ts
clear the wiring for the grid lights.
Reverse thi s procedure to reinstall the CRT. Refer
to adjustment procedure for CRT tilt.
PREAMPLIFIERS CH ANN EL
A a nd B
DC B A L A N CE
NOTE: It is not necessary to remove the PS163 from
its case to adjust DC BALANCE. A misadjustment of
the DC BALANCE will result in a position shift of the
trace as the preamplifier PPV PER DIV. switch is
switched in the 1, 2, 5 sequence.
1. Depress the AUTO TRIGGERED HORIZONTAL
SWEEP push button, set the TIME BASE - FRE
QUENCY switch to the lmSec./DIV position, and
set the preamp INPUT COUPLING switch to the
center ground position.
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2. Set the preamp PPV PER DIV. switch to the .5
position, and adjus t the TRACE POSITION control to
center the trace on the major horizontal grid line.
3 . Turn the preamp PPV PER DIV. switch to the .05
position, and adjust the DC BALANCE control to re-
center the trace.
4. Repeat steps 2 and 3 until there is no shift in the
trace position.
C AL I B RA T IO N
The preamplifier calibration adju stments (R131, R
134, R137, and R140) are horizontally mounted P.C.
pots located on the top side of the preamplifier P. C,
boards. Access to these controls for adjustment is
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through holes punched through the P.C.board. All
that is necessary to calibrate the PS163 preamplifiers
is an accurate DC voltage sourc e as shown below:
HORIZONTAL SWEEP: AUTO TRIGGER
TIME BASE - FREQUENCY .5mSec./DIV
1. Dep ress the AUTO TRIGGERED HORIZONTAL
SWEEP pushbutton switch, set the TIME BASE -
FREQUENCY switch to the lmSec./DIV position,
tu rn the center knob of the PPV PER DIV switch on
the preamplifier fully clockwise, and set the INPUT
COUPLING switch to the center ground position.
2. Connect the PS163 through the low cap probe to
the voltage source, adjust the voltage source for 1 volt,
adjust the TRACE POSITION control to center the
trace on the major horizontal grid line, and set the
PPV PER DIV switch to the .5 position.
3. Push the INPUT COUPLING switch to the DC
position, and adjust R131 for a trace deflection of 2
divisions.
4. Return the INPUT COUPLING switch to the cen
ter ground position, set the PPV PER DIV switch to
the .2 position, an d readjust the TRACE POSITION
control if necessary to center the trace on the major
horizontal grid line.
5. Pu sh the INPUT COUPLING switch to the DC
position an d adjust R134 for a trace deflection of 5
divisions.
6. Return the INPUT COUPLING switch to the
center ground position, adjust the voltage source for
.2 volts, set the PPV PER DIV switch to the .1 posi
tion, and recenter the trace if necessary.
VERTICAL INPUT: A
CHANNEL A PPV PER DIV .5 VOLTS/DIV
1. Use one of the 39G34 low cap probes to connect
the output of the 2V PP calibrator to the input of
CHANNEL A. Adjust the probe compensation cap
acitor Cl for a square wave with a flat top.
2. Use the same 39G34 probe to connect the 2V PP
calibrate signal to the CHANNEL B preamplifier,
press the B VERTICAL INPUT button, and the INT B
HORIZONTAL SYNC button. Adjust C113 in chan
nel B preamplifier for a square wave with a flat top.
10 : 1 A TT EN U AT O R
C O MPE NS A TI O N
1. With the 2V PP calibrate signal still applied to the
CHANNEL B input, turn the CHANNEL B PPV PER
DIV switch to the 1 volt position.
2. Adjust C100 for a square corner on the leading
edge of the square wave.
3 . Adjust C102 to remove any tilt on the top of the
square wave.
4. Repeat step s 2 and 3 as neces sary to obtain best
respo nse to the calibrate signal.
7. Pu sh the INPUT COUPLING switch to the DC
position and adjust R137 for a trace deflection of 2
divisions.
8. Return the INPUT COUPLING switch to the cen
ter ground position, set the PPV PER DIV switch to
the .05 position, and recenter the trace if necessary.
9. Push the INPUT COUPLING switch to the DC
position, and adjust R140 for a trace deflection of 4
divisions.
AT TE NU AT OR
F RE QU EN C Y C OMP E NS A TI O N
The first step in compensating the input attenuators
on the PS163 is to match the input capacity of the
CHANNEL A and CHANNEL B preamplifiers. Pro
ceed with the set up as follows:
HORIZONTAL SYNC: Int. A
In order to adjust the 100:1 and 1,000:1 attenuators
you will need at least a 200V PP square wave. If you
do not have such a signal available, the circuit shown
below should provide a square wave good enough for
attenuator compensation.
200 V SCOPE BH-
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Page 9
TR is a NPN Silicon with a VCE of at least 200 volts,
and a power disipation of 3 to 5 watts. This type is
used as the video output transistor in some TV re
ceivers.
TIME BASE - FREQUENCY
VERTICAL INPUT
CHANNEL A INPUT
COUPLING SWITCH
.5mSEC/DIV
A
CENTER GROUND
100:1 A TT EN U AT OR
C O MP E NS A TI O N
1. Use the 39G34 probe to connect a 200V PP square
wave to the input of CHANNEL B preamplifier, and
set the CHANNEL B PPV PER DIV switch to the 50
volt position.
2. Adjust C105 for a squ are corner on the leading
edge of the square wave.
3 . Adjust C104 to remove any tilt on the top of the
square wave.
4. Repeat steps 2 and 3 as necessary.
1000:1 A T TE NU A TO R
C O MP E N S AT I O N
1. With the 200V PP square wave still applied to the
CHANNEL B preamp, turn the CHANNEL B PPV
PER DIV switch to the 100 volt position.
2. Adjust Cl 08 for a square corner on the leading edge
of the square wave.
3. Adjust C107 to remove any tilt on the corner of
the square wave.
4. Adjust C110 to remove any tilt on the top of the
square wave.
5. Repeat steps 2, 3 and 4 as nece ssary.
1. Adjust R267 the stability control until the trace
just disappears.
2. Press the AUTO TRIGGERED HORIZONTAL
SWEEP; and check that the trace blinks on.
DIFFERENTIAL C OMP A RI T O R
B AL A NC E
Set controls as follows:
HORIZONTAL SYNC
SYNC POLARITY
HORIZONTAL SWEEP
TIME BASE - FREQUENCY
VERTICAL INPUT
CHANNEL A INPUT
COUPLING SWITCH
CHANNEL A PPV/DIV
1 . Connect the output of the 2V PP calibrator to the
input of CHANNEL A using the 39G34 low cap
probe.
2 . Adjust R233 for a locked in wave form.
3 . Turn the TIME BASE - FREQUENCY switch to
the 50uSec/DIV position, and check to see that the
square wave stays locked in.
4. If the square wave does not stay locked in, retouch
the stability control R267 until it does.
INT A
POSITIVE
AUTO TRIGGERED
,5mSec/DIV
A
AC COUPLED
2V/DIV
SWE EP SPEED an d SW EEP W ID T H
To compensate the CHANNEL A preamplifier repeat
the preceeding procedure with the signal connected to
the input of CHANNEL A, the INT A HORIZONTAL
SYNC button pushed, and usin g the adjustments of
the CHANNEL A preamplifier.
TIME BASE
STABILITY
Set the controls as follows:
HORIZONTAL SYNC
SYNC POLARITY
HORIZONTAL SWEEP
8
INT A
POSITIVE
MANUAL TRIGGERED
Set controls as follows:
HORIZONTAL SYNC
SYNC POLARITY
HORIZONTAL SWEEP
TIME BASE - FREQUENCY
VERTICAL INPUT
CHANNEL A PPV PER DIV
1 . Connect the CHANNEL A input to the yellow/
green wire on the terminal strip mounted on the rear
apron of the chassis.
2 . Adjust R317 for a trace 11 cm long.
3. Turn the CHANNEL A PPV PER DIV switch to
.5V/DIV. and adjust the HORIZONTAL POSITION
INT A
POSITIVE
AUTO TRIGGERED
2mSec/DIV
A
5/DIV
Page 10
control so that the wave form crosse s the major hor
izontal grid line at the left edge of the graticule.
VERTICAL INPUT A
CHANNEL A PPV PER DIV 10V/DIV
4 . Be sure that the center knob of the TIME BASE -
FREQUENCY switch is fully clockwise, and adjust
R286 so that one cycle of the 60Hz wave is 8.3cm
long.
5 X E X P AN D a nd
PO S IT IO N V ER NIE R
Set controls as follows:
HORIZONTAL SYNC
SYNC POLARITY
HORIZONTAL SWEEP
TIME BASE - FREQUENCY
VERTICAL INPUT
CHANNEL A PPV PER DIV
1. Connect the output of the 2V PP calibrator to the
input of CHANNEL A.
2. Adjust the center knob of the TIME BASE - FRE
QUENCY switch for 10 complete square waves in
10c m.
3. Pull the HORIZONTAL POSITION control to act
ivate the 5X expand, and adjust R319 for two com
plete square waves in 10cm.
INT A
POSITIVE
AUTO TRIGGERED
,5mSec/DIV
A
.5V/DIV
1. Connect the CHANNEL A input to the Yellow/
green wire on the terminal strip mounted on the rear
apron of the chassis.
2. Set R215 to the center of the range that produces a
stable pattern.
B L A NKI N G LEVEL a nd OUT PUT
ST AGE C OLLE CTO R V O L TA G E
A DJ U ST M E N T
Push the VECTOR VERTICAL INPUT BUTTON, set
the CHANNEL A and CHANNEL B INPUT COU
PLING sw itches to the center ground position, and se t
the INTENSITY control 15 degrees from the counter
clock-wise position.
1. Adjust R604 on the high voltage supply board so
the trace is just extinguished.
2 . Adjust the CHANNEL A TRACE POSITION con
trol for equal voltages on the Collectors of TR506 and
TR507 on the vertical output board, and adjust the
CHANNEL B TRACE POSITION control for equal
voltages on the collectors of TR506 and TR507 on
the horizontal output board.
4. Turn the TIME BASE - FREQUENCY switch to
the .lmSec/DIV position, and turn the center knob
fully clockwise.
5. Adjust the HORIZONTAL POSITION control so
that the negative going transition of the square wave
lines up with the major vertical graph screen division.
6. Carefully push the HORIZONTAL POSITION con
trol back in with out turning it, and adjust T321 and
R322 to keep the negative transient lined up on the
major vertical division.
7 . Repeat steps 5 and 6 until the trace does not shift
when the 5X expand is activated.
SY N C S EP AR A TO R B AL A N CE
A DJ US T ME N T
Set controls as follows:
HORIZONTAL SYNC
SYNC POLARITY
HORIZONTAL SWEEP
TIME BASE - FREQUENCY
INT A
POSITIVE
AUTO TRIGGERED
TV VERTICAL
3. Adjust R520 on the vertical and horizontal out
put boards for exactly 115 volts on the collectors of
TR506 and TR507.
CAL. V OL TS 2 V PP
First be sure that the preamplifiers are properly cal
ibrated, then adjust R409 on the display board, so
that the calibrate square wave fills four squares with
the preamp VPP/DIV switch set to .5V/DIV.
CRT TILT AD JU S TM EN T
Adjust the front panel controls to produce a clean
horizontal trace with no vertical deflection. Loosen
the screw on top of the front CRT mounting bracket,
directly behind th e front panel. Rotate the CRT, using
level provided on CRT bas e socket, until the trace is
aligned with the horizontal graticule lines. Retighten
mounting bracket screw.
9
Page 11
SERVICE PROCEDURES
The PS163 is a complex instrument, and repair should only be attempted by a technician
qualified and experienced in the repair of miniature solid state electronic equipment. Note:
if you do wish to service your PS163, special care must be taken when making measurements or
connections to the +25, +15, and -25 volt power supplies . The ripple filter transistors TR
700 - TR702 are not short circuit protected, and even a momentary short to the output of one
of these supplies will result in the destruction of the associ ated transistor.
For those who wish to service their own PS163, we have included a series of trouble charts to
help isolate the section in which the problem is located. Also included are both the component
view and foil side view of the printed circuit boards. The foil side view of the board shows the
location of all tra nsistors, adjustmen ts and test points. The charts that accompany the views of
each board show the incircuit gain and leakage readings for all transistors as measured with a
Sencore TF151A, as well as the incircuit res istance readings from each transistor pin to ground
as measured with a Sencore FE160, Field Effect Multimeter, using low power ohms. All of the
above measurements were taken under the following conditions.
HORIZONTAL SYNC
SYNC POLARITY
HORIZONTAL SWEEP
TIME BASE - FREQUENCY
PPV PER DIV
INPUT COUPLING
To aid in locating a particular component, the PS163 schematic reference numbers have been
coded to indicate which section of the PS163 the component is located in. The coding is as
follows:
1-99
100 -199
200 - 399
400 - 499
500 - 599
600 - 699
700 - 799
INT A
POSITIVE
AUTO TRIGGERED
lOOmSec/DIV
.05V/DIV
DC COUPLED
Chassis
Pre-amplifier
Time base an d trigger circuit
Display board and 2V calibrator
Output amplifier
Η. V. Power supply
L. V. Power supply
TR O UB LE C H A RT S
10
Page 12
NO VERTICAL DEFLECTION
ONE CHANNEL ONLY
(Horizontal Sweep Normal)
UNSTABLE SYNC
1 1
Page 13
NO HORIZONTAL SWEEP
(Normal Vertical Deflection)
NO TRACE
1 2
Page 14
NO VERTICAL DEFLECTION
BOTH CHANNELS
(Horizontal Sweep Normal)
1 3
Page 15
19B L/ W'
B OARD L A Y O UT S A ND TA BLES
TR200
F ig. 1-A. Foil side view with board legend.
Fi g. 1-B. Component side view.
14
Page 16
TIME BASE BOARD
TR
NUMBER
200 U1837
2 01
202
2 03
204
205
206
207
208
209
210 2N5172
211
212
213 TP4174
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
22 9
23 0
231
232
233
234
235
236
TYPE
NUMBER
U1837 NCH
2N5227 PNP
2N5227 PNP
2N5227 PNP
U1837 NCH
U1837 NCH
2N5227 PNP
2N5227
2N5172
2N5227
2N5227 PNP
TP4274
2N5172
2N5172
2N5172
TP4247
TP4247
2N5172
2N4248
2N5172
2N4248
2N4248 PNP
2N4248
2N4248
2N5172
2N5172
2N5461 PCH
2N4248 PNP
2N4248 PNP
2N4248
2N5227
2N5227 PNP
2N4248
MPF103 NCH
POL.
NCH
PNP
NPN
NPN
PNP
NPN
NPN
NPN
NPN
NPN
NPN
NPN
NPN
PNP
NPN
PNP
PNP
PNP
NPN
NPN
PNP
PNP
PNP
BETA/
GM*
4500
4500
35
27
70
4500
4500
25
35
150
125
200
190
60
65
150
00
125
35
75
inf.
inf.
150
125
125
100
50
150
200
2500
100
125
400
125
125
125
test out
LEAKAGE RESISTANCE TO GROUND
Icbo Igss* (,08V max) f
In uA
1,000
1,000
500
500
70
1,000
1,000
600
600
400
400
600
600
500
750
65
500
200
80
750
2,000
1,500
200
200
80 0
20
2,000
0
75
0
3,000
5,000
0
80
80
95
circuit
E/S
2.8K
2.8K
3.9K
3.9K
750
2.5K
2.5K
3.9K
3.9K
9.5K
9.5K
3.9K
3.9K
470
470
0
0
270
3.6K
8
inf.
inf.
IK
0
0
60 22K
700K (2)
4.4K
1.5K
24K
27K
1.1K
inf.
inf.
2.4K
1.7K
B/G
0
0
2.8K
2.8K
50K
0(1)
1.4M (1)
2.5K
2.5K
2.9K
2.9K
4.8K
4.8K
3K
3.6K
44K
55K
15K
33K
2.7K
2.2K 1.4K
2.2K
12K
inf.
41K 6.8K
110K 100K
15K
15K
inf.
1.5K
24K
2.8K
12K 39K
8.5K
39K 2.2K
1M
C/D
2.8K
2.8K
3.IK
3.1K
3.3K
2.5K
2.5K
2.9K
2.9K
4.8K
4.8K
3K
3K
1.4K
1.6K
1.4K
5.7K
1.4K
2.7K
2.2K
1.1K
6.8K
6.8K
IK
inf.
15K
IK
IK
IK
inf.
30K
1.4K
(1) will change with Sync Polarity
(2) varie s with Time/Div. switch
* BETA & LEAKAGE measurement s taken with SENCORE TF17 or TF151.
f RESISTANCE measurements taken with SENCORE Hi-LO Multimeter.
15
Page 17
T R 4
N O T E : V IO L E T W I R E O N X _ T R 3^
W ^ ' ^ LM ^ i 7 RR n A k n E O A N O T E : W H IT E W IR E O N V E R T I C A L
W I R E O N HOR IZ. B O ARD < T > B O A R D , G R A Y W IR E O N H O R IZ
7 X T W IR E R E D O N X 5 5 X
j tr7 tr^
v B O A R D
S E N C O R E Ψ 9 TR ^ n n
4 3 B 3 9 V W r 9
R 2 0 W W
4 R ~ Λ Α Λ - N O T B C E N T E R β γ i d
V > H O R IZ. B O A R D , O O O
V R l Λ ru ' A M \ /CDT N / N /
B L A C K O N V E f i T .
BOARD .
/"TJR8
Fig. 2-A. Foil side view with board legend.
S E N C O R E
4 3 B 3 9
R 2 0
T
5 0 0 1
TR
NUMBER
500
501
502
503
504
505
506
507
508
509
TYPE
NUMBER
2N5227
2N5227
SE3002
SE3002
D40D1
D40D1
D40N1
D40N1
2N5172
2N5172
POL.
PNP
PNP
NPN
NPN
NPN
NPN
NPN
NPN
NPN
NPN
Fi g. 2- B. Component side view.
OUTPUT BOARD
BETA/
GM*
90
175
90
80
65
38
10
10
50
1000
LEAKAGE
Icbo Igss*
In uA
2,000
2,000
2,000
2,000
0
0
40
40
0
5,000+
7 \
RESISTANCE TO GROUND
(.08V)f
E/S
39K
39K
2.2K
2.2K
inf.
inf.
inf.
inf.
IK
2.2K
B/G
0
0
2.3K
2.3K
2.3K
2.3K
0
0
8K
8K
C /D
2.2K
2.2K
0
0
inf.
inf.
cap
cap
inf.
8K
1 6
Page 18
Fi g. 3-A. Foil side view with board legend .
Fig. 3-B. Componen t side view.
PRE AMPLIFIER BOARD
TR
NUMBER NUMBER
100 MPF102
101 MPF102 NCH 4500 5 1.7K
102A TD101 NPN 250 5,000 13K 2K 1.2K
102B TD101 NPN 250 5,000 13K 2K
103A TD101 NPN
103B TD101 NPN 250 0 inf.
104 SE3002 NPN 90 0 1.3K 4.7K
105 SE3002 NPN 50
106
107 2N4248
108A TD401
108B TD401 PNP 60 500 inf.
109 SE3002
(1) Varies with trace position control
TYPE
SE3002 NPN 50 1,000 inf.
POL.
NCH
PNP 150 0 1.3K
PNP
NPN
BETA/
GM*
3800 1,000 1.7K
250
60 500
90
LEAKAGE
Icbo Igss*
In uA
0 inf. 13K inf.
1,000 inf. 1.2K
0 10K inf.
RESISTANCE
(.08V max)t
E/S B/G
inf. 2.6K
TO GROUND
C/D
1.4M 1.2K
1M 1.2K
1.2K
13K inf.
inf.
2.5K
1.2K
2.8K inf.
2.6K 6K(1)
2.5K
6K(1)
900
17
Page 19
R9
-Λ/V—
■
' ) & ■ ©
| R22
^CR3°XR7q
O © Q R Sq .
2E^ ^I4B
CR k C R ^ I
<$ QCR6CRI0g^l
^13
RE O 26)bfTR^
R270
8R HR 3R Ο O
© &&
9B I2B 4B
A O O O 0 “
9 M 7 .
))5 B R
66/W
7V
Fig. 4-A. Foil side view with board legend.
<5 ^
r
6G/W
o
3R HR 8R
ooo
7V 4B I2B 9B
Ο ΛΛΛ.
Fig. 4-B. Component side view .
^ ω
-f^m
OJ2
Φ o
£o
ο 33
m
g ™
o ™
JR 400
I6Y
o
TR4
©
TR6
isrO O 'r
Ι 4Βό ό 2Β
1 3
o
TR5
2
TR3
TR TYPE POL.
NUMBER NUMBER
400 SE3002 NPN
401 SE3002 NPN
402 2N4248 PNP
403 2N4248 PNP
404 SE3002 NPN
405 SE3002 NPN
406 2N4248 PNP
407 2N4248 PNP
18
DISPLAY BOARD
BETA/ LEAKAGE
GM*
16
17
150
125
65
55
200
65
Icbo Igss
In uA
125
125
175
500
125
125
500
200
RESISTANCE
(.08V)t
E/S
0
0
2K
12K
7.5
7.5
12K
0
TO GROUND
B/G
30K
30K
6K
4.4K
30K
30K
4.4K
10K
C/D
3.5K
3.5K
12K
1.8K
4.4K
4.4K
1.8K
3.9K
Page 20
1 7 OR
Ο
21BL 20BL
IQBlfv <0>
o oBBL
26 25 24 23 22
ooooo
w w w w w _
TR2
9BL I OR
oo
7BL<^> <^y -2R
6V<0>04R
δ δ δ δ ο ο ^ [0 ^ % 28
γ γ γ γ γ γ 8t]V ^ v e g bl
SENCORE
43B42
Fig. 5-A. Foil side view with board lege n d .
TR
NUMBER
700
701
702
TYPE
NUMBER
D40D1
D41D1
D40D1
Y
eC>
POL.
NPN
PNP
NPN
o
TR600
λ /TOP SINGLE WIRE
/ X f r o m t r a n s fo rm e r
/ΗΙ®!
/ /γτ
yv \ y TRANSFORMER
c sy /V b o tto m single w ire
V FROM TRANSFORMER
v r
a :
2W
<5
SENC ORE
43B 4I
Λ HI CR4 ^
L V SUPPLY BOARD
BETA/
GM*
200
250
150
8G
O
R4
7BR 3GY
Fi g. 5-B. Component side view.
LEAKAGE
Icbo Igss*
In uA
5.000
5.000
5.000
RESISTANCE TO GROUND
(,08V max) f
E/S B/G C/D
750
IK
1.3K
cap
cap
cap
cap
cap
cap
Fi g. 6-A. Foil side view with board legen d.
TYPE
NUMBER
600
601
602 T1P29A NPN
NUMBER
2N3877A NPN
2N3877A NPN inf.
POL.TR
Η V SUPPLY BOARD
BETA/
GM*
200 110
27 1,000
LEAKAGE
Icbo Igss*
In uA
Component side view.
RESISTANCE TO GROUND
(.08V max)t
E/S
inf. 6.3M
500 100K
0 3.9K 750
B/G
43K 35K
C/D
43K
19
Page 21
SENCORE SAFETY REMINDERS
When testing electronic equipment, there is always a danger p resent. Unexpected high voltages
can be present at un usual locations in defective equipment. The technician should become
familiar with the device he is working on and observe the following precautions.
1. An isolation transformer should always be used on equipment having the chassis tied to
one side of the AC power line. The ca se of the PS163 is connected to the earth ground
sid e of the AC line through the third wire of the line cord. If the chassis of the equipment
being serviced is connected to the other side of the AC line, a severe shock hazard will be
present. In addition, a s soon as the PS163 ground lead is connected to the chassis the
resultant short circuit will fuse the ground clip of the scope to the chassis of the equip
ment being serviced, and blow the fuse to your service bench.
2. When making test lead connections to high voltage points, remove the power. If this can
not be done, be sure to avoid contact with other equipment or metal objects. Place one
hand in your pocket as a safety precaution and stand on an insulated floor to reduce the
possibility of shock.
3 . Discharge filter capacitors before connecting test leads to them. Capacitors can store a
charg e that could be dangerous to the technician.
4. Be sure your equipment is in good order. Broken or frayed test leads can be extremely
dange rous and can expose the technician to dangerous potentials.
5. Remove the test leads immediately after the test has been completed to reduce the
possibility of shock.
6. Do not work alone when working on hazardous circuits. Always have another person
close by in case of accident. Remember, even a minor shock can be the cause of a more
serious accident, such as falling against the equipment, or coming in contact with higher
voltages.
SERVICE A N D WARRANTY
You have just purchased one of the finest oscilloscopes available on the market today.
The PS163 has been inspected and tested twice at the factory. It has also passed a rugged
use test by a Field Engineer in our Zero Defects test area.
If something should happen, the PS163 is covered by a standard 90 day warranty as ex
plained by the warranty policy enclosed with your instrument. For best service on
warranty work, return the PS163 directly to our Factory Service Division. Be sure to
state the nature of the defect to assure rapid return to you.
If you wish to maintain your own PS163, we have enclosed a schemat ic, parts list and
trouble chart. Any parts needed may be ordered directly from the Factory Service
Division.
We reserve the right to examine defective components before an in-warranty replacement
part is issued.
Form 686
Printed in U.S.A.
Page 22
AH American Made
at /es s cost than foreign imports!
....
SENCORE
3 200 SE N CO RE DR IVE, S I OU X FALLS, SO UTH DAKOTA 5 7107
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