Philips GM 5605 User manual

MANUAL
PHILIPS
Cathode ray oscilloscope
GM 5605
66-(02 58.2-10 1/86-4/01

Contents
GENERAL
I. Introduction 7
II. Technical data 8
III. Accessories 10
DIRECTIONS FORUSEAND APPLICATIONS
I. Installation
A. Adjusting tothe localvoltage 11
B. Earthing 12
C. Checking before switching on12
D. Switching on13
II. Operation
A. Preliminarysetting 14
B. Displayingwaveforms 15
C.Howtouse the X input 16
•v,v*$r -j-
% •
*•• T.
III.Applications
A. Measuring the amplitude 18
B. Using theX input 18
C. Displaying a diode characteristic 21
D. Displaying a hysteresis loop 21
SERVICE DATA
I. Circuitdescription
A.Y amplifier 23
B. Trigger pulse shaper 25
C. Timebase generator
D.X amplifier
E. Cathode ray tube
-3-|
F. Supply part

Contents 3
II. Gaining access tothe parts
A. Removing the cabinet panels 33
B. Removing the knobs 34
C. Removing the front panel 34
D. Removing the window andthe graticule 34
III.Maintenance
A. Waferswitches 36
B. Cabinet panels 36
IV. Adjustingelements and theirfunctions 37
V. Checking and adjusting
A. Mainscurrent 38
B. Supply voltage + 280V 38
C. Ripple onthe supplyvoltage + 280V 38
D. Barrel and pincushiondistortion 38
E. Focusing and astigmatism 39
F.Y amplifier 39
G.X amplifier 41
H. Time base generator 45
VI. Replacing parts
A. Thermalfuse 47
B. Supplytransformer 47
C. Switches SK2, SK3 and SK4 47
D. Switchwafers SK2 48
E. Switch wafers SK3 48
F. Switch wafers SK4 48
G. Potentiometers onthe front panel . 48
H.CRTand valves 48
VII. Fault finding54
VIII. List of parts
A. List of mechanicalparts 55
B. List of electricalparts 58

List of figures
1 Adjusting tothe local mains voltage
2The apparatus ia tilted position
3 Preliminarysetting
4 Functions ofthe controls and sockets
5 Measuring the amplitude
6 Examples of Lissajous figures
7 Determining the phaseanglessine 9? = a/b
8 Network for quadrant determination
9 Someparticularphaseangles
10 Displaying the diodecharacteristic oftheOA85
11 Displaying a hysteresisloop
12 Blockdiagram ofthe "bootstrap" integrator
13 Circuitdiagram ofthe "bootstrap" integrator
14 Removing the cabinetpanels
15 Removing the knobs
16 Removing the bottomplate and frontpanel
17 Removing the graticule
18 Squarewaveresponse oftheY amplifier
19 Squarewaveresponse oftheX amplifier
20 Replacing the thermal fuse
21 Replacing the supplytransformer
22 Anodeconnection
23 Positioning the c.r.t.
24 Right-hand side view with adjusting elements and units
25 Left-handsideviewwith adjusting elements and units
26 Front view with adjustingelements
27 Blockdiagram
28 Unit A;Y amplifier
1 1
12
14
17
18
19
19
20
20
21
26
27
34
35
40
43
47
47
49
49
50
50
65

List of figures 5
29 Circuit diagram oftheY amplifier 67
30 Unit D; time base generator and trigger pulse shaper 71
31 Circuit diagram ofthe triggerpulse shaper 73
32 UnitC; X amplifier 79
33 Circuitdiagram oftheX amplifier 81
34 Unit B; beam control 85
35 Circuitdiagram ofthe c.r.t. circuit 87
36 Unit E; H.T.unit 91
37 Unit F; supply part 92
38 Circuitdiagram of the supply part 95
Important!
In correspondence concerning this apparatus please quote the type number
and serial number as given on the plate at the back of the apparatus.

GENERAL PART
Introduction I
The cathode ray oscilloscope CM 5605 hasan extensive fieldof applica-
tion andis particularlysuitable forusein service workshops andfor
educationalpurposes. ForX andY deflection the apparatus contains d.c.
amplifiers having the sameproperties (X-Y oscilloscope). TheGM 5605
is, therefore,extremelysuitable for displaying the relationshipbetween
two quantities, e.g. frequency and phaserelationships. Moreover, voltages
canbe displayed asa function of time by means ofthe incorporated
time-basegenerator.

8
Technical data
II
Properties expressed in numerical values for which a tolerance has been
stated are guaranteed at nominal mains voltages onthe voltageadapter.
Numerical values without tolerances indicate the properties ofthe average
instrument andare only given forthe information ofthe user.
Cathode-ray tubecircuit
Tube
a. type
b. effective screenarea
c. totalacceleratingvoltage
Graticule
V amplifier
Type
Deflection sensitivity
Frequencyresponse
Overshoot
Sweepexpansion
Input
a. inputsockets
b. inputresistance
c. inputcapacitance
d. maximum permissible input
voltage at d.c. input
DH7-78 flat screen(otherscreentypes canbe
supplied)
6x 5 cm (width X height)
1750V
10 X 8div. (1 div. = 5.5mm)
d.c. amplifier
adjustable to8 calibratedvalues: 0.01-0.03-
0.1-0.3-1-3-10-30 V/div.
Tolerance: ±3%
Between the steps, the sensitivity canbe continu-
ouslyadjusted ina ratio of 1: 3.5 (uncalibrated).
0-200 kc/s (—3 dB). Viathe capacitor input
the bandwidth is:5 c/s-200 kc/s.
1 % for pulseswith a rise time of ^ 25ns
3X the useful screenheight, i.e. 1.5X upwards
and downwardsfrom the centre.
At maximumexpansion the peaks ofthe signal
canbe displayed undistorted by means ofthe
vertical shift control.
4-mm plugsockets
500 kO
45 pFin position "0.01 V/div." ofthe attenuator
switch
25 pFinthe positions "0.03" and "0.1 V/div."
55 pFinthe otherpositions.
400 Vr.m.s.

Technical data 9
e. Maximumpermissible d.c.
voltage atthe a.c. input
f. RC time ofthe capacitorinput
X amplifier
Type
Deflectionsensitivity
Response curve
Overshoot
Sweepexpansion
Input
a. inputsockets
b. inputresistance
c. input capacitance
d. maximumpermissible input
voltage on d.c. input
e. Maximumpermissible
d.c,voltage onthe a.c. input
f- RC time ofthe capacitorinput
Phase difference ofthe amplifiers
Phase difference
Time base generator
Sweeptimes
Mode of operation
300V
50 ms
d.c. amplifier
adjustable to7 calibratedvalues: 0.03-0.1-
0.3-1-3-10-30 V/div.
Tolerance: ±3%
Between the steps, the sensitivity canbe continu-
ously adjusted ina ratio of 1: 3.5 (uncalibrated).
0-200 kc/s (— 3 dB). Viathe capacitor input
the bandwidth is:5 c/s-200 kc/s.
1 % for pulseswith a risetime ^ 25ns.
3x the useful screenwidth, i.e. 1.5x tothe
left andtothe right from the centre.
At maximumexpansion the peaks ofthe signal
canbe displayedundistorted by means ofthe
horizontal shift control.
4-mm plug sockets
500 kH
45 pFin position "0.03 V/div" ofthe attenuator
switch
25 pFinthe position "0.1 V/div."
55 pFinthe other positions.
400 Vr.m.s.
300V
50ms
^ 5°for frequencies of 0-200 kc/s, provided
that thetwo continuousattenuatorcontrols are
adjusted to " xI".
adjustable in12 steps from 20 fxs/div. to100
ms/div. ata timebaselength of10 divisions,
triggered

10 Accessories
Triggering internal or external
a. requiredpicture height forin-0.5 division for frequencies of5 c/s-200kc/s.
ternaltriggering
0.5 Vp-p for frequencies of5 c/s-200kc/s.
The maximum voltageamounts to10 Vp_p (in
view of crosstalk).
1 MO//20 pF
b. requiredvoltage for external
triggering
c. inputimpedance of socket
"EXT.TRIGG."
Supply
Mains voltage
Influence of mains-voltagevari-
ations of± 10%
Mechanical data
Dimensions
Weight
voltageadapter for 110-125-145-200-220
and245V.The mainsfrequency may range from
40-100 c/s (mainsfrequencies < 50c/s only at
nominal mains voltage). Powerconsumption is
SOW.
TheY andX deflectionsensitivitychanges
inversely proportional tothe mainsvoltage.
height 25cm
width 16cm
depth 35cm
10kg
v
Accessories
III
1 mains flex
1 manual
2 test cables

11
DIRECTIONS FORUSE
AND APPLICATIONS
Installation I
A. ADJUSTING TOTHE LOCAL MAINS VOLTAGE
The apparatus canbe adjusted to mainsvoltages of 110-125-145-
200-220 and245V by means ofa voltage adapter.
The adjustedvalue canbe readthrough the round opening inthe rear
panel. The instrument is adjusted to anothermainsvoltage as follows.
- Remove the cover plate atthe rear (Fig. 1).
- Pull the adapter outa little,turn it until the correct voltage value is
uppermost and then press the adapterbackagain.
- Refit the cover plate.
j -
. .
.
V
-
Fig. L Adjusting to the local mains
voltage

12 Installation
B. EARTHING
Earth the instrument in accordance with the local safety regulations. This
may be done
-viathe mains flex, if the apparatus hasa 3-core mains flex provided with
a plugwithrim-earthing contacts, or
- viaoneofthe earthing sockets ("•=•") atthe front ofthe apparatus.
Double earthing connections may cause hum and must be avoided.
C CHECKINGBEFORESWITCHING ON
- Check the setting ofthe mainsvoltageadapter(seesection A).
- Checkwhether the apparatus has beenproperlyearthed(see section B).
-Set knob "INTENSE to position "0".
- Connect the apparatus tothe mains viathe mains flex.
Fig. 2. If desired the apparatus can be tilted by means of the stand provided
on the bottom

Installation 13
D. SWITCHING ON
Switch onthe apparatus by setting knob "INTENS." fromposition "0"
to approximately its centralposition.
A stationary picture of maximum brightness, left on the screen for too long
a time may permanently damage the screen.

14
Operation
II
A. PRELIMINARY SETTING
-Set all knobs tothe positions indicated in Fig. 3.
- Adjust the time base line tothe centre ofthe screen by means ofthe
knobs "jYf and "<-X-»".
- Check whether the time baseline appearshorizontally onthe screen.
If necessary, reposition the picture tube in accordance with section
VI.H.l.
- Adjust the definition andthe brightness ofthe picture by means ofthe
controls "FOCUS." and "INTENS.".
17*.
Fig. 3. Preliminary setting

Operation 15
Notes
-Ifthe time base line cannot be displayed by means of knobs "<—X-V*
and "|Yj", potentiometer "DC-Balance" oftheY amplifier (accessible
onthe left-hand side ofthe apparatus)must be turneduntil the time
base line appears. This potentiometermust be adjusted in such a way,
that the picture does not shift ifthe continuous control "Y AMPL." is
turned(see section V.F.I).
- If knob "X AMPL." isin position "0.3 V/div.", knob "DC-Balance"
oftheX amplifier(accessible onthe right-handside ofthe apparatus)
must be adjusted in such a way,that the light spot onthe screen no
longer shifts ifthe continuouscontrol is turned(seesectionV.G. I).
Withcathode ray tubes, astigmatism may arise. Then the light spot on
the screen isnot round. This canbe corrected by means of potentio-
meter "ASTIGM.", accessible onthe left-handside ofthe apparatus.
B. DISPLAYING WAVEFORMS
1. Time base internally triggered
- Adjust as describedunder"Preliminary setting" (page14).
Turnknob "STAB.*' anti-clockwise, until the timebase line just dis-
appears.
- Apply a voltage tothe d.c. or a.c.input oftheY amplifier.
Turn knob "STAB." until a stable picture is obtained.
- Place knobs "Y AMPL." and "NV* inthe required position.
Note; Ifno triggering occurs at minimum setting (0.5div.), potentio-
meter "LEVEL" (R513, intheright-hand sidewall)must be adjusted
according to section V.H.I.
2. Time base externally triggered
- Adjust as describedunder"Preliminary setting" (page14).
Turnknob "STAB." anti-clockwise until the timebase line justdis-
appears.
- Apply a voltage tothe d.c. or a.c.input oftheY amplifier.
- Apply an externaltriggervoltage to socket "EXT.TRIGG." onthe
right-hand side ofthe apparatus (ifthe picturemust be stationary,this
voltage must be derivedfrom the voltagefromwhich theY signal also
originates).
- Place knobs "Y AMPL." and "N\ atthe required position.

16 Operation
C.HOWTOUSETHEX INPUT
If a voltage is applied to both amplifiers, thesevoltages canbe compared
with eachother and their relationships canbe made visible.
Some of theseapplications are alsomentioned in chapterIII.
- Connect the voltages tobe compared tothe input sockets "DC (AC) Y
AMPL." and"DC (AC) X AMPL.".
- Placeswitches "Y AMPL." and "X AMPL." inthe desiredposition.
- Setthe continuouscontrol "X AMPL" to position " X1".
The picture cannowbe brought onthe screen by means ofthe shift con-
trols "jYf" and "<-X-»-".
In order to obtaingoodstationarypictures, the voltages onthetwo
amplifier inputsshould be synchronous.
•

Operation 11
Horl(««l picture (ta
VcrUcil (Hcun dull
Step .-Iit* W Uw vertici
•rffUtUTWHt ,4 UK1
BnC|.U>eu cu»n>J/ii«IH.uic «
W iKc- pKI-re *Imi
I it.-rniil trtf—l-r nmul IH hr .---I lui
tnuii-rmj; wKk »• nli-nul
,-iu k ,J |Kr i., •« nnr l-fc. .
, -X AWI'l. " .. p.rt,u— ->H-J
••'. |. 1<K>U* k..i ii.wlal .. 1..I.. il, (in
I..MLH.I. 1>V(' ih. li.... i,n, ;;. iv i ii ,i
II IWllClKd IH>)
Cxndnuuui
>elt«lUVt1l'
l u( «w twntonul
HI JKHLlHJA
Fig. 4. Functions of the controls and sockets

18
Applications
III
A. MEASURING THE AMPLITUDE
- Measure the distance between the peaks, c.j/. 3 div.(seeFig. 5)
- Determine the position of knob "Y AMI*!./1
(continuous attenuator in position " x l"j, e.g. 10 V/div.
Now the amplitude amounts to10 (attenu;,i0r position) x3 (picture
height) = 30V.
\.
PEM 217
EI:S
K- 5. Measuring the amplitude
B. USING THEX INPUT
The followingexamples canbe mentioned:
Frequency measurements
Phasemeasurements
Displayingcharacteristics
Etc.
Frequency measurement by means of Lissajous figures
Ifa voltage of unknown frequency is applied totheY amplifier, the light
spot onthe screen will describe a so-called Lissajous figure, under the
influence ofa voltage of knownfrequencyapplied totheX amplifier.
Dependent onthe frequency the image will show a certain number of
peaks. The unknown frequency
number of peaks atthetop
X knownfrequency.
number of peaks atthe side
Some common Lissajous figuresare shown in Fig. 6,in which 50c/sis
used as reference frequency.

Applications 19
50c/s 100 c/s
150c/s
75 c/s
Fig. 6. Examples of Lissajous figures
Phase measurements
Phase angles canbe measured by means ofa Lissajous figure (ellipse)
The imagemustthen lie symmetricallyround the centre.
The following appliesirrespective ofthe quadrant in which the phase
angle is found: the sine of phaseangle <p is determined bythe ratio a/b
(see Fig. 7).
Inthefigure, sine <p — 2 div./4div. — 0.5. The phaseangle <p is then 30°.
If thetopofthe ellipse isatthe right ofthe screen, the phaseangle isin
the first quadrant (30°) orinthe fourth quadrant (360°-30° = 330°).
P£M 290
E12J
Fig. 7. Determining the phase angles sine <p = a/b

20 Applications
Ifthetopisatthe left ofthe screen, the angle isinthe secondquadrant
(180°-30° - 150°) orinthe third quadrant(180 + 30°= 210°). For
determination ofthe quadrant proceed as follows:
- Include a circuit as shown in Fig. 8 into the lead totheX amplifier with
closed switch.
- Open the switch and turn the potentiometer from minimum to maxi-
mum value. In doing so,the shape ofthe ellipse must clearly change.
PEM 289
E127
Fig. 8. Network for quadrant determination
Phase angle (thus also a) Quadrant
becomes
Quadrant
larger
smaller
2. (90°-I80°)
3. (180°-270°)
1. (0°-90°)
4. (270°-360°)
If the pictureappears asa straight diagonal onthe screen, the phase
angle is0° (360°) or 180°(Fig. 9).
y=0°(360°) ¥> =90°(270°)
PEM2M
Fig. 9. Some particular phase angles

Applications 21
C. DISPLAYING A DIODECHARACTERISTIC
In displaying a diodecharacteristic the current through the diode is
plotted asa function ofthe voltage across the diode. For this, usecanbe
made ofthe circuitshown in Fig. 10. Voltage source E supplies a low
sinewavevoltage. The resistance R must be smallwithrespect tothe
expectedinternalresistance ofthe diode. The voltage across R, which is
directlyproportional tothe anodecurrent, isfedtotheY amplifier. The
anode voltage is applied totheX amplifier. Nowa curve is displayed
which represents the relationshipbetween anode current and anode
voltage.
Fig. 10. Displaying the diode characteristic of the OA 85
D. DISPLAYING A HYSTERESIS LOOP
In displaying hysteresis loops of magnetic material, the magnetic induction
B is plotted asa function ofthefield strength H. Ifthe iron core ofa coil
contains noair gaps, thefield strength is proportional tothe current
through the number of windings. The primary current is thus a measure
ofthefield strength H.A resistor Rpis connected in series with the pri-
mary winding. The voltage across this resistor is applied totheX input
(seeFig.12).
The voltage across the secondarywinding isUs = k.dB/dt.
Here k isa constant.
This voltage is integrated byanRC network (R» I/o>c). The voltage
across the capacitorthenbecomes Uc = k.B/R.C. The induction Bis thus
proportional tothe voltage across the capacitor. This voltage, which is
lowand must be adequatelyamplified, isfedtotheY amplifier.