leader lbo-516 电路图.pdf

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1、 RadioFans.CN 收音机爱 好者资料库 WARNING! THE SERVICING INSTRUCTIONS CONTAINED IN THIS MANUAL ARE FOR USE BY QUALIFIED PERSONNEL ONLY. TO AVOID ELECTRIC SHOCK, DO NOT PERFORM ANY SERVICING OTHER THAN THAT CONTAINED IN THE OPERATING INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO SO. RadioFans.CN 收音机爱 好者资料库 TABL

2、E OF CONTENTS (Continued) 3-4 CALIBRATION OUTPUT ADJUSTMENT .30 3-5 A TIMEBASE ALIGNMENT .30 3-5-1 Slow Sweep Time .30 3-5-2 Sweep Length .30 3-5-3 Fast Sweep Time .30 3-5-4 Sweep Start Point .30 3-5-5 Timebase Accuracy Check .30 3-6 A TIMEBASE X10 MAGNIFIER ADJUSTMENT .30 3-6-1 Magnifier Positionin

3、g .30 3-6-2 Magnifier Speed Accuracy .30 3-7 B TIMEBASE ALIGNMENT .30 3-7-1 Slow Sweep Time .30 3-7-2 Length Adjustment .31 3-7-3 Sweep Start Point .31 3-7-4 Fast Sweep Time .31 3-7-5 Timebase Accuracy Check .31 3-7-6 Start Points Alignment .31 3-8 VERTICAL AMPLIFIERS .31 3-8-1 DC Balance Adjustment

4、 .31 3-8-2 Attenuator Step Balance .30 3-8-3 X1 AC Gain Compensation .31 3-8-4 X10 AC Gain Compensation .31 3-8-5 Gain Calibration .31 3-8-6 CH-2 Invert Balance Adjustment .32 3-8-7 CH-1/CH-2 Input Capacitance Adjustment .32 3-8-8 CH-1/CH-2 Input Attenuator Compensation .32 3-8-9 CH-3 Direct Input C

5、apacitance Adjustment .32 3-8-10 CH-3 Attenuator Compensation .32 3-8-11 CH-3 Attenuator Input Capacitance Adjustment .32 3-8-12 CH-3 Gain Adjustment .32 3-8-13 CH-1 Output Level Adjustment .32 3-8-14 CH-1/CH-2 HF Pulse Response Alignment .32 3-8-15 CH-1/CH-2 Frequency Response Check .33 3-8-16 CH-1

6、 Output Pulse Response .33 3-8-17 CH-1/CH-2 X10 Magnifier Bandwidth Check .33 3-8-18 Vertical Position Control Centering .33 3-8-19 ADD Balance Adjustment .33 3-9 TRIGGER CIRCUITRY ADJUSTMENTS .33 3-9-1 Trigger Balance and Centering Alignments .33 3-9-2 Trigger Balance Adjustments for Multitrace Mod

7、es .33 3-9-3 Preset Trigger Adjustment .34 3-9-4 CH-3 Pulse Response Adjustment .34 3-9-5 Internal Trigger-Pulse Response Adjustment .34 3-10 X-Y MODE ADJUSTMENTS .34 3-10-1 Gain Adjustment .34 3-10-2 Balance Adjustment .34 4. REPLACEMENT PARTS LIST 37 5. BLOCK DIAGRAM, SCHEMATICS AND P.C. BOARDS 51

8、 RadioFans.CN 收音机爱 好者资料库 3. MAINTENANCE AND CALIBRATION 3-0. The following test equipment is required to perform the calibration/maintenance procedures described in this section. The performance specifications given are the minimum necessary to accurately calibrate the oscilloscope. Description Mini

9、mum Specifications 1. Digital Voltmeter DC Voltage Range: 0-200 VDC Accuracy: +0.5% 2. High Voltage DC Voltage Range: 0-2000 VDC Voltmeter Accuracy: -+ 1% 3. Frequency Counter Frequency Range: 100 Hz - 200 MHz Overall Accuracy: +0.001% 4. Time Mark Generator Marker Outputs: 2nS - 0.5 S with calibrat

10、ed + 5% offset adjust Accuracy: -+0.1% 5. Sine Wave Generator Frequency Range: lkHz - 200 kHz Output Level: 15 mV - 5 Vp.p Accuracy: -+.3 dB, 1 MHz - 200 MHz as frequency is changed 6. Test Oscilloscope 100 MHz Bandwidth 7. Square Wave Frequency: 1 kHz - 100kHz, -+1% Generator Output Level: I mV - 1

11、.0 Vp-p, -+1% Rise Time: 3 nS 8. Amplitude Calibrator Output: 1 kHz square wave Frequency Accuracy: -+0.25% Output Level: 2 mV - 20 Vp-p 9. Capacitance Meter Range: 0-50 pF Accuracy: - 1% 3-1. INITIAL SETUP CONDITIONS POWER switch .Pushed in A INTEN control . Centered* B INTEN control . Centered* IL

12、LUM control . Clockwise FOCUS control . Centered* AC/GND/DC switches . DC VOLTS/DIV switches . 20mV VARIABLE controls . Clockwise X10 MAG switches Pushed in Vertical POSITION controls . Centered*. PULL QUAD control . Pushed in PULL TRIPLE control . Pushed in V MODE switches . CH-1 CH-2 INV switch .

13、Out DLY TIME MULT control . Counterclockwise. COUPLING switch . AC SOURCE switch .CH-1 LEVEL control . 0 HOLDOFF control . Detented counter clockwise and pulled out A/B TRACE SEP control . Centered SLOPE switch . Out HORIZ DISPLAY switches. . A START switch . Out SWEEP MODE switches . AUTO A TIME/DI

14、V switch . .5 mS B TIME/DIV switch . .1 mS A VARIABLE control . Clockwise Horizontal POSITION control . Centered* * Adjusted afterwards for best viewing. Allow 30 minutes warmup before making any adjust- ments. Remove the top and bottom covers to gain access to test points and internal adjustments.

15、3-2 POWER SUPPLY CHECK AND ADJUSTMENT 3-2-1 -8 Volt Adjustment Connect a digital voltmeter s positive lead to the scope chassis (GND), and the voltmeter s negative lead to TP-5 lo- cated on PCB T-3153. Adjust VR-1 for -8.0 V. 3-2-2 Power Supply Check Check the voltages listed below by moving the vol

16、tmeter s negative lead to chassis ground, and applying the positive lead, in turn, to each of the associated test points on PCB T-3153. Nominal Test Point Voltage Tolerance TP-I +100 +98 VDC to 102VDC TP-2 + 50 49 51 TP-3 + 12 11.75 12.25 TP-4 + 8 7.85 8.15 TP-6 + 5 4.8 5.2 TP-7 + 19 17.5 20.5 3-2-3

17、 High-Voltage Adjustment Turn off the unit under test. Connect the positive lead of a HV voltmeter to chassis ground, and its negative lead to TP-8. Turn the scope on and allow a 2 minute warmup. Adjust VR-2 on PCB T-3162 for a reading of - 1950 volts. Connect an X10 probe to the test oscilloscope a

18、nd hold its tip close to the face of the CRT under test. The high-voltage ripple displayed on the test oscilloscope should be less than 0.1Vp-p. 3-3. CRT CONTROL ADJUSTMENTS Make sure the controls are set according to the initial setup conditions in Paragraph 3-1 before starting the following adjust

19、ments. 3-3-1 Intensity Range Adjustment. Center the CH- 1 trace on the CRT with the vertical POSITION control. Set the A INTEN control knob mark to an approximate 45 angle as shown in Figure 3-1. Adjust VR-I on PCB T-3162 until the trace becomes just barely visible. 3-3-2 Astigmatism Adjustment Conn

20、ect a sine wave generator to the CH-1 input connec- tor. Set generator frequency and output to produce five or six sine waves. Set output level and POSITION controls for a centered display 6 cm high. (Peaks of the sine waves just touching the graticule lines I cm above and below the bottom and topmo

21、st graticule lines.) Adjust A INTENS and FOCUS for a medium-bright, sharp display. Adjust VR- 1 on PCB T- 3157 for optimum overall sharpness. 29 3-4. CALIBRATION OUTPUT ADJUSTMENT Connect the test oscilloscope to the CAL connector on the fron panel of the LBO-516. Adjust VR-1 on PCB T-3287 for a CAL

22、 output level of 0.5 Vp-p +-1%. The duty cycle of the square wave should be 45-55%. Connect the CAL output to a frequency counter; the fre- quency should be 1000 Hz + - 10%. 3-5. A TIMEBASE ALIGNMENT 3.5-1 Slow Sweep Time Return the oscilloscope to the initial setup conditions. (See Paragraph 3-1).

23、Adjust the time-mark generator for an output of .5 mS and connect it to the CH-1 input connector. Using the horizontal POSITION control, align the first mark with the leftmost vertical graticule line. Adjust VR-22 on PCB T-3158 to align each subsequent mark with a major vertical graticule line. 3.5-

24、2 Sweep Length With the same conditions as in the previous paragraph, adjust the horizontal POSITION control to align the third mark with the leftmost vertical graticule line. (See Figure 3-2.) Adjust VR-1 on PCB T-3158 so the 13th mark is fully dis- played on the CRT screen. 3.5-3 Fast Sweep Time R

25、eturn the oscilloscope to the initial setup conditions. (See Paragraph 3-1). Set the A TIME/DIV switch to 0.5 PS. Set the time-mark generator to 0.5/.PS and connect it to the CH- 1 input connector. Using the horizontal POSITION control, align the first mark with the leftmost vertical graticule line.

26、 (See Figure 3-2.) Adjust VC-22 on PCB T-3158 to align each subsequent mark with a major vertical graticule line. 3.5-4 Sweep Start Point Return the oscilloscope to the initial setup conditions. (See Paragraph 3-1). Set the A TIME/DIV switch to 0.1 mS. With the horizontal POSITION control, adjust th

27、e trace startpoint to the first minor division (0,2 major division). Change the A T1ME/DIV switch to 50/aS and adjust VC-1 on PCB T-3158 so the sweep starts at the leftmost vertical graticule line. 3.5-5 Timebase Accuracy Check Return the oscilloscope to the initial setup conditions. (See Paragraph

28、3-1). Set the A TIME/DIV switch to 0.5 S. Set the time-mark generator to 0.5 S and connect it to the CH- 1 input connector. Align the first mark with the left-most vertical graticule line. Adjust the generator so that each subsequent mark is aligned with a major vertical graticule line. Repeat for e

29、ach A TIME/DIV switch setting from.2 S to 0.2PS, verifying that the timebase accuracy is within +-2% at each sweep speed. 3-6. A TIMEBASE X10 MAGNIFIER ADJUSTMENT 3-6-1 Magnifier Positioning Return the oscilloscope to the initial setup conditions. (See Paragraph 3-1.) Set the CH-1 AC/GND/DC switch t

30、o GND, and press the INTEN BY B pushbutton. Set the B TIME/DIV switch to .5 mS. Adjust the horizontal POSITION control to start the A trace on the leftmost vertical graticule line. Adjust the DLY TIME MULT control to start the B (intensified) trace at the center vertical graticule line. Center the horizontal POSITION control knob. Pull the timebase X10 MAG switch. Adjust VR-33 on PCB T-3158 so that the B sweep starts on the center graticule line. Afterward, push in the X 10 MAG