GoldStar os7020 电路图.pdf

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1、GoldStar MODEL OS- 7020 OSCILLOSCOPE SERVICE MANUAL GoklStar Praclslon Co . Ltd. RadioFans.CN 收音机爱 好者资料库 GoldStar MODEL OS- 7020 OSCILLOSCOPE SERVICE MANUAL GoldStar Pn!dslon Co . Ltd. RadioFans.CN 收音机爱 好者资料库 CONTENTS 1. General - Page 1 2. Specifications - 2 3. Accessories- 5 4. External View - - 7

2、 5 P rev en t i v e Ma i n ten an c e - - - - - - - - - - - - - - - - - - - - - 9 5-1 Cleaning - 9 5-2 Visual inspection - 10 5-3 Periodical calibration - 10 6. Measuring instruction- 11 6-1 Probe phase adjustment - 11 6-2 Voltage measurement - 12 6-3 Frequency measurement - 14 6-4 Rise (fall) time

3、measurement - 15 JI 6-5 Pulse width measurement- 16 6-6 Phase measurement- 16 7. Circuit description- 18 8. Calibration - 21 8-1 Period of check and calibration - 21 8-2 Test equipment required- 21 8-3 Preliminary procedure - 21 8-4 Preliminary control settings 23 8-5 Initial starting procedure- 23

4、9. Semiconductor lead configurations- 34 10. Electrical parts list -35 ( 1) ATTENUATOR - - - - - - - - - - - - - 35 ( 2) CBl INPUT AMP - 36 RadioFans.CN 收音机爱 好者资料库 (3) CH2 INPUT AMP.- 39 (4) VERTICAL CONTROL- 42 (5) VERTICAL MAIN AMP.- 44 (6) TRIGGER AMP. - 46 (7) SWEEP GENERATOR- 47 (8) TIMING CIRC

5、UIT- 49 (9) HORIZONTAL MAIN AMP. - 50 (10) CHOP PULSE GENERATOR- 52 (11) HIGH VOLT :-, . ro I l I l WAN.g=- - . (J CJ u - IGoldStor1 osouoscoPE os.1010 - l - - :.,-.;- 0 0 Ol + =i - Q, = I 1 - r 1 I - -.:=:=:=j - ./-. .,._ _,- UL. 1 I =:=:=:=: _J 5. PREVENTIVE MAINTENACE These are the precautions on

6、 preventive maintenance which will protect the instrument from trouble and keep it clean for a long time. 5-1 Cleaning Since the extent of instrument smearing depends on the ambient condition in which the oscilloscope is used, the frequjncy of the cleaning operations cannot be defined initially. Cle

7、aning should be accomplished as required. Dust deposited inside the instrument affects the normal flow of cooling air and invites the local overheating of components parts of results in trouble. Smeared switch contacts of connector pins can be the cause of defective contact, and smearing of the circ

8、uit can cause arcing between circuits, particularly in moist season. Cleaning agents recommended and those prohibited are listed as below. Recornrneded agent Alcohol, gasoline of keroscene Prohibited agent I I I Acetone, tri-ethyl-ketone lacquer thinner or agent containing ketone series so L vent Cl

9、eaning the cver Normal sruedriGg of the cover can be cleaned by washing the cover with a neutral chemical cleaner. For greasy smearing, use a recommended agent with a soft cloth. Front and other panels. Clean the smeared panel with a soft cloth moistened with a recommended agent. Dust in-instrument

10、The best way to remove dust inside the instrument is the blowing of compressed air. Remove persistent dust with a soft painting brush and blow the air again. CRT The CRT screen will be smeared if it is used for too long without the filter. Ordinary dust of finger print left on the CRT can be cleaned

11、 by a soft cloth. Use a soft cloth moisted with alcohol to remove persistent smearing. Filter The filter may be clogged when used for a long time. Dust or fingerprint can be cleaned with a dry soft cloth. Use a soft cloth moisted with alcohol to remove persistent smearing. 5-2 Visual inspection The

12、instrument should be inspected occasionally for such defects as broken connections, improperly seated transistors, damaged circuit boards, and heat-damaged parts. The correc- tive procedure for most visible defects is apparent ; howe- ver, articular care must be taken if heat-damaged components are

13、found. Overheating usually indicates other trouble in the instrument; therefore, correcting the cause of the overheating is impor- tant to prevent the recurrance of the damage. 5-3 Periodical Calibration In order to use the oscilloscope accurately, periodical calibration of circuit is essential. Whe

14、n this oscilloscope is used frequently, a calibration will be required at every l,000hours of operation. 10 The frequency of calibration may be extended to 6 months, if the oscilloscope is used infrequently. 6. MEASURING INSTRUCTION 6-1 Probe phase Adjustment Proper adjustment of the probe phasing i

15、s required before measurements as the incorrect phasing results in eroneous measurements when the XLO position is selected. 1. Set the controls as follows VOLTS/DIV VARIABLE TIME/DIV (sweep)VARIABLE O.lV CAL o.sms CAL (Horizontal)POSITION CENTER 2. Set the probe switch to x10 and connect the probe b

16、etween the input connector and the CAL OUT terminal. 3. Display the calibration voltage waveform with 5 divisions amplitude 4. Adjust the variable capacitor of the probe using the small driver, and set the top of the waveform to the correct phasing shown in Fig. 6-1 I I I I I I - - - - _ ._ - - - -

17、I I I I : I . . . . . I . I I I I - - - - - - _ ,. _ - - - - - I , r y r r I I r r r! r r I . - - - . - - -t- - - - - I . . . I I I correct OVER -Shoot UNDER - Shoot Fig 6-1. Phasing of probe o Volt1ge is pplitd t I I I I I l I I I I I- o - volt rlfererce llnR I AC-CiND-DC switch to CiND) :i . 1 . r

18、 . +-+- T I I I I I l - I I I Fig 6-2. DC Voltage measurement 12 6-2-2 AC voltage measurement The measurement of the voltage waveform is performed as follows ; Set the VOLTS/DIV switch in order to obtain the amplitude for easy reading, read the ampl- itude as shown in Fig. 6-3 and calculate by equat

19、ion(!) or (2). When the waveform superimposed on DC current is measu- red, set the AC-GND-DC switch to DC in order to measure the value including DC component, or set this switch to AC in order to measure AC component only. The measured value by means of this procedure is peak value(Vp-p). Effective

20、 value(Vrms) of a sine wave signal can be Effective voltage(Vrms) = given by Equation(). Peak voltage(Vp-p) 2 ff - (3) Vp-p rz l . r r 1 T I I I I I Fig 6-3. AC Votae measurement 13 6-3 Frequency measurement The first method; Calculate the one cycle time(interval) of the input signal and obtain the

21、frequency by equation(4) Frequency(Hz) = l (C) - (4) PERIOD(S) The second method; Count the repetition number N per 10 divisions in the viewing area, and calculate the frequency by Equation (5) N(C) ( 5 Frequency(Hz) = - TIME/DIV setting value(s/div)xl0(div . When N is large(30-50), the second metho

22、d can give a high accuracy level than that obtained with the first method. This accuracy is approximately equal to the rated accuracy of sweep rate. However, when N is small, the count below decimal point becomes very ambiguous, which results in considerable error. For the measurement of comparative

23、ly low frequencies having a simple pattern such as sine wave, square wave, triangle wave, and sawtooth wave, measurement with high.accuracy can be effected by the following method; Operate the oscilloscope as an X-Y scope, make the Lissajous pattern by applying the signal of which frequency is known

24、, and read the necessary value. ;o . I t t. I + , . , . , . 0% I 4 ti., I ,lo I 1- N:34.5 j Fig 6-4. Frequency measurement 14 6-4 Rise(Fall) time measurement 1. Display the pulse waveform vertically and horizontally in the same manner as for the pulsewidth measurement procedure. 2. Turn the horizont

25、al POSITION control in order to set the upper 10% point of the waveform on the vertical center line of the graticule. Read the distance Tl between the vertic 1 center line and the point at which the rising (falling) edge crosses the horizontal center line. 3. Shift and set the lower 10% point of the

26、 waveform to the vertical center line of the graticule as shown by the dotted line in Fig 6-5. Read the distance T2 between the vertical center line and the point at which the rising (or falling) edge crosses the horizontal center line. 4. Calculate the rise(or fall) time by substituting the sum of

27、Tl and T2 - I I. I I I - 90, . . . . . . . . . . . . . . . . . . . . +. ffl l Horlz mtal ente Lbw l I fl I to . . . . . . . . . . -J. I I . . . . . . . . . . . )2 I I I ii Vertical tant1r Um Fig 6-5 Rise(or fall) time measurement 15 6-5 Pulsewidth Measurement The basic pulsewidth measurement procedu

28、re is as follows ; 1. Display the pulse waveform vertically so that the distance between the top part of the pulse waveform and the hori- zontal center line of the graticule may be equal to the distance between the bottom part of the pulse and the horizontal center line as shown in Fig. 6-6 90 . 4.

29、J I. I rz r r T T r r r 1 1 1 I Fig 6-6 Pulsewidth measurement 2. Set the TIME/DIV switch in order to make the easy observa- tion of the signal. 3. Read the distance between cnters of rising and falling edges, i.e., the distance between two points at which pulse edges cross the horizontal center lin

30、e of the graticule. 6-6 Phase Measurment The measurement of phase difference between two signals, there are the following two methods; The first one is the Lissajous pattern method by using I the instrument as an X-Y scope. The phase difference of 16 signals can be calculated form the amplitude A an

31、d B of the pattern shown in Fig 6-7 and by Equation(6) Phase differnece(deg) sin - (6) B 1 I - . . . . . . . . . . . . . . . . . . . . . . . V V -0 . - - , 111 -0 ,C: C: 111 0 .0 - s. s. (I) 0 bO .c bO . s. 0 . (I) -c, .c C: U 111 - 111 0 . . S. (I) -g 111 - c,s . C: 0 N . s. 0 .c . 0 C - U bO . 111

32、 0 . . I- -c, C 111 (I) g, .0 . Cl_. 111. 0. Ill C .(I) 0 0. (I) E .c: 0 U 0 , - 0. 0. :, Ill ,. (I) 3: 0 0. 0 (I) .c: u bD C . . . . tlS . C 0 N . S. 0 .c: 0 (I) .c: u . I c1S Ill ., . C C (I) (I) o. E E . O Ill. 0:, .,., s. -c, (I) c1S . : -0 - C 0. 111 E Ill 111 - 0 111 (I) 0 .c: .: C) I- .: .c:

33、. -0 . 3: -0 c: c,s .0 s. (I) . . . . 0. E c,s - c,s - . 0 1-4 0 c: 0 . . 111 1-4 (I) 0. 0 s. (I) bO bO . I- .c: l 0 C 0 . . (I) :10 ,:!OO . (I) - - N 0 .0 :I: . - :E M . E 111 o 0 . , (.) If I-, C . Ill E .c: u Oz Oi:Q If - I) 11 1-4 (J 0 C: c,s 0 -0 (I) (I) C: 0. c: E o . () - Ill Ill E 1-4 .c 0 0

34、 c:;o (I) Ir. C c: - 0 (I) 0 (J C - If 0 -0 (I) - 0. . 0 - . u z 0: i:o u z i:Q Ill I- 0 . 0 (I) c: c: 0 u C 0 . . 0. . I- 111 1-4 3: 0 I., (I) c,s ,. s. rd (I) :, C: 0- (I) V) bO S. (I) . (I) E . - 0 - tlS . . bD . 0 I S. (I) C: (I) bO t; c1S E Ill 1-4 E o . E- (I) - .0 rd u c: 0 . . rd c: . E S. (

35、I) E- t- S. 0 . tlS :, C . 00 I- 0 . 0 (I) C: C: 0 (.) I E- . a- 22 8-4. Preliminary control settings Set the instrument controls as follows, when starting the calibration procedures. Controls Settings Controls Settings FOCUS Midrange TRACE ROTATION As desired - VERT - V. POSITION Mid r-ange , pushe

36、d in SWP VAR Fully clockwise V. VARIABLE CAL, fully clockwise INPUT COUPLING GND. - TRIG - (AC-GND-DC) VOLTS/DIV 5 mV/DIV TRIG. COUPLE AC V.MODE CH1 LEVEL Midrange, Normal CH2INV Normal, Pushed in SLOPE + Normal - HORZ - H. POSITION Midrange MODE AUTO - PULL X10 MAG oral,. Pushed in TIME/DIV 1 ms TR

37、IG. SOURCE CH1 8-5. !nitial starting procedure. 1. Rotate the INTENsity control to the midrange and set the POWER switch to ON. 2. Wait a few seconds for the cathode ray tube (CRT) to warm up. A trace should appear on the CRT. 3. If tz-acedteappeaz-s , increase (clockwise) the INTENsity control sett

38、ing until the trace is easily observed, or roughly check/adjust the DC balance to get a trace as same as 4. Adjust the FOCUS control for the. best focused display. 5. Readjust the POSITION controls if necessary, to center the trace. Power Supply System * NOTE Before you start operation, see the adju

39、stment locations in the pullout pages. control setting Preset the controls as given in the preliminary control setting. (D Check low voltage supply, if necessary. a. Connect the digital voltmeter(DVM) between the +12V line (P810-4) and ground. ; +11.7 to +lL.JV b. Connect the DVM between the -lLV Li

40、ne(P810 -L) and ground. ; -lL.J to -11.?V c. Connect the DVM between the +5V line(P810 -3) and ground. ; +4.a to 5.LV d. Connect the DVM between the +51V line(P810 -5) and ground. ; +50.5 to 51.5V i) Conect THE PROB(l0 xl) with X+(R674) and X-(R663) on the horizontal board. li) Set OSCOPE VOLT/DIV t

41、o 5V. RANGE and also, the lines of wave form of CHl and CHL must be coincided with Ref Line. NOTE; Ref to figure as following. ili) Set the H-POSITION to the left side. iv) Adjust VR805 as following 24 V V - - - - = = . t . . . 1 . . . . . . - - - - .- .,._ - - - - - . J J 2 . I I Ref lVl = VL) Vl M

42、UST BE SAME AS VL e. Connect the DVM between the +160V linelP810 -6) andground. ; +150 to +170V f. Connect the DVM between the +180V linel810 -7) and ground. ; +170 to 190V g. Connect the DVM between the +18V linelP804-l) and ground. ; +17 to +19V 2. Check high voltage supply a. Connect the DVM betw

43、een the H.V.lP61L-6) and ground with a high voltage probe. b. Check for a reading of -1, 995 to -1, 805V 25 DISPLAY Conlrol selling I Preset the controls s given in the preliminary conlrol selling. . Check/ adjust INTEN ADJ. Set the Trig MODE s w itc h lo lhe AUTO, and set lhe TIME/DIV s w it c h to

44、 the 1 ms. a. Connect the digital voltmeter (DVM) to the R688 (or CR614) and ground. b. Adjust the INTENSITY control so that Lile DVM indicates 20 V. c. Observe lhe trace of CRT. .d. Adjust the grid bias adjustment VR610 for the trace makes a just appear. Check/ adjust trace rotation. a. Position the trace to the center graticu