The bandwidth has been extended from 20 to 30MHz, the sweep Horizontal Deflection rate increased to 10ns/div. and improvements added to the already legendary HAMEG auto triggering system. The HM303 is the ideal instrument for waveform Time coefficients: 20 calibrated steps display in the DC to 100MHz frequency range.
Adjustment Procedure Subject to change without notice...
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WARNINGS contained therein. • should only be performed by suitable qualified and experienced service personnel, or should be referred to one of the HAMEG companies listed on the rear cover of the manual. Test Instruments required: Scope Tester HZ60-2.
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Table of Contents R1008: +141 Volt supply................29 R1016: +12 Volt supply................29 VR7000: Trace Rotation Check..............29 R1004 : CRT minimum intensity..............29 R712RT maximum intensity................ 29 R712: Mean Y-plate Potential Channel I............. 29 R714: Mean Y-plate Potential Channel II.
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PS-Board Front panel YPA-Board PS-Board XY-Board Pin 2 Pin 4 Subject to change without notice...
R1008: +141 Volt supply. WARNING: To avoid damage use a fully insulated screwdriver! Locate and identify R1008 (1) on PS-Board (screened section). Locate 8 pole checkpoint socket on XY-Board and identify pin 2. Adjust R1008 (1) for exactly +141Volts (± 0.1 Volt). R1016: +12 Volt supply.
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YPA-Board PS-Board Subject to change without notice...
RV6021 : Astigmatism correction. Locate and identify RV6021 (8) on CRT-Board. Connect a 1MHz squarewave signal with 25mVpp at 50Ω (HZ22) to input CHI. Set time base to 0.1µs/div. Adjust FOCUS control for optimum sharpness. Adjust RV6021 (8) until leading edge and top of signal have equal sharpness. Recheck range of FOCUS control.
YPA-Board (13) R139: 100Hz Squarewave 5mV/div CH I. Locate and identify R139 (13) in CH I section of the YPA-Board. Connect a 25mV/100Hz squarewave signal via 50Ω cable and 50Ω through terminator to input channel I. Set time base to 2ms/div. Check that DC input coupling is selected.
(14) R134: 100Hz Squarewave 1mV/div Adjustment CH I. Locate and identify R134 (14) in CH I section of the YPA-Board. Connect a 5mV/100Hz squarewave signal via 50Ω cable and 50Ω through terminator to input channel I. Press Yx5 channel I (in!) for 1mV/div. Set time base to 2ms/div.
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YPA-Board Subject to change without notice...
(21) RV2005 (A), RV2006 (C), CV2000 (D) and CV2001 (B): Y-Final Amplifier. Connect a 1MHz squarewave signal of 25mV via 50Ω cable and 50Ω through termination to input CH I. Check that DC input coupling is selected. Set time base to 0.2µs/div. Locate and identify the adjustment points RV2005 (21A), RV2006 (21B), CV2000 (21C) and CV2001 (21D) on XY-Board.
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YPA-Board XY-Board Pin 1 Pin 5 TB-Board Subject to change without notice...
(25) R663: ADDition/Offset. Press DUAL pushbutton (in!). Locate and identify R663 (25) on YPA-Board. Set input coupling CH I and II to GD. Move both baselines with Y-POS. I and II controls to the horizontal center line of the graticule. Release DUAL pushbutton (out!).
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YPA-Board TB-Board XY-Board Subject to change without notice...
(31) RV2234: X-Magnification x10. Locate and identify RV2234 (31) on XY-Board. Press pushbutton X-Mag. x10. Set time base to 50µs/div. Set time mark generator to f= 20kHz and connect signal to CH I input. Set X-POS control to mechanical center. Using X-POS control, move the visible time mark to the first left graticule line.
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XY-Board CT-Board Pin 1 Pin 14 Subject to change without notice...
(36) RV2301 (A), 4322 (B): Component Tester Y-Position and Tilt. Release all pushbuttons (out!). Press COMPONENT TESTER pushbutton (in!). Locate and identify RV2301 (36A) on XY-Board. Adjust RV2301 (36A) to shift the approx. 8 div. horizontal component tester trace to the horizontal center of the CRT graticule.
Set input coupling CH I to GD. Remove signal cable from input CH I and connect it to TRIG.INP. socket. Do not change generator settings. Now the Trigger-LED should be ON again. (41) Video Trigger Check. Set CH I input coupling switch to DC. Connect video signal with positiv sync.
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