Hameg HM 303-4, Service Manual

Subject to change without notice

27

Table of Contents

(1)

R1008: +141 Volt supply. ............................................................................ 29

(2)

R1016: +12 Volt supply. .............................................................................. 29

(3)

VR7000: Trace Rotation Check. .................................................................. 29

(4)

R1004 : CRT minimum intensity. ................................................................ 29

(5)

R712RT maximum intensity. ....................................................................... 29

(6)

R712: Mean Y-plate Potential Channel I. .................................................... 29

(7)

R714: Mean Y-plate Potential Channel II. ................................................... 29

(8)

RV6021 : Astigmatism correction. .............................................................. 31

(9)

R640: Y-Gain CH I. ...................................................................................... 31

(10)

R122: FET operating point CH I. ................................................................. 31

(11)

R203: Invert-Balance CH I. ......................................................................... 31

(12)

R177: Variable-Balance CH I. ...................................................................... 31

(13)

R139: 100Hz Squarewave 5mV/div CH I. ................................................... 32

(14)

R134: 100Hz Squarewave 1mV/div Adjustment CH I. ............................... 33

(15)

R658: Y-Gain CH II. ..................................................................................... 33

(16)

R422: FET operating point CH II. ................................................................ 33

(17)

R503: Invert-Balance CH II. ........................................................................ 33

(18)

R477: Variable-Balance CH II. ..................................................................... 33

(19)

R439: 100Hz Squarewave 5mV/div CH II. .................................................. 33

(20)

R434: 100Hz Squarewave 1mV/div CH II. .................................................. 33

(21)

RV2005 (A), RV2006 (C), CV2000 (D) and CV2001 (B): Y-Final Amplifier. .. 35

(22)

Y-Amplifier Bandwidth Check. .................................................................... 35

(23)

C113/111/102/105: Attenuator Compensation CH I. .................................. 35

(24)

C413/411/402/405: Attenuator Compensation CH II. ................................. 35

(25)

R663: ADDition/Offset. ............................................................................... 37

(26)

RV2417 (A), RV2418 (B): Overscan. ........................................................... 37

(27)

RV3519: Sweep start voltage. .................................................................... 37

(28)

RV2225: X-Magnification x1. ...................................................................... 37

(29)

RV2260: X-Symmetry. ................................................................................ 37

(30)

RV3591 (A)/3589 (C), CV3511 (B): Time base. ........................................... 37

(31)

RV2234: X-Magnification x10. .................................................................... 39

(32)

R624: XY-Gain ............................................................................................. 39

(33)

RV3293: Trigger-Symmetry ......................................................................... 39

(34)

R612: DC-Triggering CH I. .......................................................................... 39

(35)

R603: DC-Triggering CH II. ......................................................................... 39

(36)

RV2301 (A), 4322 (B): Component Tester Y-Position and Tilt. .................... 41

(37)

VR8940: Calibrator Output. ........................................................................ 41

(38)

Trigger Filter Check. .................................................................................... 41

(39)

Triggerbandwidth Check. ............................................................................ 41

(40)

External Trigger Check. ............................................................................... 41

(41)

Video Trigger Check. ................................................................................... 42

NOTE

The adjustment procedures assume that the instrument had once been properly adjusted in the
factory and adjustments are required due to temperature drift or the replacement of defective
components.

Before starting each adjustment procedure, set the oscilloscope to the following basic settings:

•

Press POWER pushbutton (in!).

•

Release all other pushbuttons (out!) except AC/DC input coupling.

•

Rotate the three variable controls (TIME/DIV. and VOLTS/DIV.) to

their (calibrated) detent positions.

•

Set TIME/DIV. switch to 50µs/div.

•

Set both VOLTS/DIV switches to 5mV/div.

•

Rotate the HOLD OFF knob fully counterclockwise.

•

Trigger coupling set to AC.

•

Set all other controls to their midrange positions.

If different settings are required, they are mentioned particularly for each subject.