Heathkit Model EUW-25

DC Oscilloscope

 

Date Calibrated:   _____/_____/_____

Calibration Procedure

 

♦    The following adjustments were initially all preset at the factory.

 

·                     All direction orientations are from the front panel looking aft.

Ancillary Equipment Needed

 

Audio Signal Generator

Frequency Counter

* * * * * * *

 

(    )         Connect the line cord to the AC power lines.

 

(    )         Adjust the FOCUS control (R56) clockwise until the switch clicks to the ON position.

               (Allow the instrument to warm up for five minutes.)

 

(    )         Adjust the FOCUS control (R56) clockwise until the trace is in focus.

 

* * * * * * *

ASTIGMATISM

 

(    )         Set the VERTICAL switch [rear panel] to the Shorted position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Shorted position.

 

♦  CAUTION: DO NOT PERMIT A HIGH INTENSITY SPOT TO REMAIN STATIONARY ON THE DISPLAY FOR ANY LENGTH OF TIME. THIS MAY DESTROY THE FLUORESCENT MATERIAL ON THE TUBE AND LEAVE A DARK SPOT.

 

(    )         Adjust the VERTICAL BEAM control (R69) [left side panel, bottom hole] until the spot is centered vertically on the graticule.

 

(    )         Adjust the HORIZONTAL BEAM control (R76) [right side panel, bottom hole] until the spot is centered horizontally on the graticule.

 

(    )         Adjust the INTENSITY control (R54) [front panel] until the spot is just visible.

 

(    )  (    )₁         Adjust the FOCUS control (R56) [front panel] until the spot is in focus.

 

(    )  (    )₂         Adjust the ASTIGMATISM control (R51) [rear panel] until the spot is the sharpest.

 

(    )         Repeat the above two * steps as necessary for the smallest and clearest possible spot.

 

* * * * * * *

VERTICAL DC BALANCE

 

(    )         Set the VERTICAL switch [rear panel] to the Shorted position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Normal position.

 

(    )  (    )₁         Adjust the VERTICAL GAIN control (R8) {red knob} [front panel] until the spot moves.

 

(    )  (    )₂         Adjust the VERTICAL DC BALANCE control (R6) [front panel] until the spot is at its original location.

 

(    )         Repeat the above two * steps as necessary until the spot does not move when the VERTICAL GAIN control (R8) is adjusted from maximum counter-clockwise to maximum clockwise.

 

* * * * * * *

HORIZONTAL DC BALANCE

 

(    )         Set the VERTICAL switch [rear panel] to the Normal position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Shorted position.

 

(    )  (    )₁         Adjust the HORIZINTAL GAIN control  (R38) {red knob} [front panel] until the spot moves.

 

(    )  (    )₂         Adjust the HORIZONTAL DC BALANCE control (R37) [front panel] until the spot is at its original location.

 

(    )         Repeat the above two * steps as necessary until the spot does not move when the HORIZONTAL GAIN control (R38) is adjusted from maximum counter-clockwise to maximum clockwise.

 

* * * * * * *

SWEEP CENTERING

 

(    )         Set the VERTICAL switch [rear panel] to the Normal position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Normal position.

 

(    )         Set the HORIZONTAL ATTENUATOR switch to the AC X 100 position.

 

(    )         Set the FREQUENCY switch to the 5 - 50 position.

 

(    )         Adjust the HORIZINTAL GAIN control (R38) {red knob} [front panel] to maximum counter-clockwise.

 

·         The trace may shift to one side as it becomes a short line.

 

(    )  (    )₁         Adjust the SWEEP CENTERING control (R66) [front panel] to position the trace in the center of the display.

 

(    )  (    )₂         Adjust the HORIZINTAL GAIN control (R38) {red knob} [front panel] clockwise and observe the trace.

 

·         When centered properly, the trace should expand equally in both directions when the HORIZINTAL GAIN control (R38) is adjusted clockwise.

 

(    )  (   )₃          If the trace does not expand equally, adjust the HORIZINTAL GAIN control (R38) {red knob} [front panel] to maximum counter-clockwise.

 

(    )         Repeat the above three * steps as necessary until, the trace is centered and will expand equally.

 

(    )         Set the HORIZONTAL ATTENUATOR switch to the AC X 10 position.

 

(    )         Adjust the HORIZINTAL GAIN control (R38) {red knob} [front panel] to maximum counter-clockwise.

 

(    )  (    )₁         Adjust the SWEEP CENTERING control (R66) [front panel] until the trace is centered on the display.

 

(    )  (    )₂         Adjust the HORIZINTAL GAIN control (R38) {red knob} [front panel] clockwise and observe the trace.

 

·         When centered properly, the trace should expand equally in both directions when the HORIZINTAL GAIN control {red knob} (R38) [front panel] is adjusted clockwise.

 

(    )  (   )₃          If the trace does not expand equally, adjust the HORIZINTAL GAIN control (R38) {red knob} [front panel] to maximum counter-clockwise.

 

(    )         Repeat the above three * steps as necessary until, the trace is centered and will expand equally.

 

* * * * * * *

CR TUBE POSITIONING

 

♦  This adjustment only needs to be performed if the trace is not horizontal across the graticule grid.

 

♦  CAUTION: The voltages on the CRT can be potentially lethal, exercise do care when performing this procedure.

 

(    )      Set the VERTICAL switch [rear panel] to the Normal position.

 

(    )      Set the HORIZONTAL switch [rear panel] to the Normal position.

 

(    )      Adjust the SWEEP GENERATOR control for a horizontal trace.

 

(    )  (    )₁         Note the two end points of the trace on the graticule screen.

 

(    )  (    )₂         Adjust the FOCUS control (R56) to the full counter-clockwise to the OFF position.

 

(    )  (    )₃         Disconnect the line cord from the AC power lines.

 

(    )      Remove the metal cabinet.

 

(    )      Loosen the mounting brackets at the neck of the CRT.

 

(    )  (    )₄         Rotate the CRT until the trace should be level on the graticule grid.

 

♦  Do not allow the CRT to slide forward and come into contact with the graticule grid.

 

(    )  (    )₅         Connect the line cord to the AC power lines.

 

(    )  (    )₆         Adjust the FOCUS control (R56) clockwise until the switch clicks to the ON position.

                        (Allow the instrument to warm up for five minutes.)

 

(    )  (    )₇         Adjust the FOCUS control (R56) clockwise until a trace is in focus.

 

(    )         If the trace is not horizontal across the graticule grid, repeat ALL the above seven marked * steps.

 

(    )      Adjust the FOCUS control (R56) to the full counter-clockwise to the OFF position.

 

(    )      Disconnect the line cord from the AC power lines.

 

(    )      Carefully retighten the mounting brackets at the neck of the CRT.

 

♦  Do not allow the CRT to slide forward and come into contact with the graticule grid.

 

(    )         Re-install the metal cabinet.

 

(    )         Connect the line cord to the AC power lines.

 

(    )         Adjust the FOCUS control (R56) clockwise until the switch clicks to the ON position.

               (Allow the instrument to warm up for five minutes.)

 

(    )         Adjust the FOCUS control (R56) clockwise until the trace is in focus.

 

* * * * * * *

VERTICAL ATTENUATOR COMPENSATION

 

(    )         Set the VERTICAL switch [rear panel] to the Normal position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Normal position.

 

(    )         Adjust a Square Wave generator, using a Frequency Counter, for a 1000 Hz output.

 

(    )         Connect the Square Wave generator output to the [front panel] Vertical input.

 

(    )         Adjust a Sine Wave generator, using a Frequency Counter, for a 1000 Hz output.

 

(    )         Connect the Sine Wave generator output to the [front panel] Horizontal input.

 

(    )  (    )₁         Set the VERTICAL ATTENUATOR switch to the AC X 10 position.

 

(    )  (    )₂         Adjust the Square Wave generator output for a six graticule peek-to-peek signal.

 

(    )  (    )₃         Adjust the X 10 VERTICAL Input trimmer (C3) [left side panel, top front hole] until a correctly compensated square wave is obtained.

 

(    )  (    )₄         Set the VERTICLE ATTENUATOR switch to the AC X 100 position.

 

(    )  (    )₅         Adjust the Square Wave generator output for a six graticule peek-to-peek signal.

 

(    )  (    )₆         Adjust the X 100 VERTICAL Input trimmer (C5) [left side panel, top rear hole] until a correctly compensated square wave is obtained.

 

(    )         Repeat the above six * steps as necessary until, no further trimmer adjustments are required.

 

(    )         Disconnect all inputs from the front panel.

 

* * * * * * *

HORIZONTAL ATTENUATOR COMPENSATION

 

(    )         Set the VERTICAL switch [rear panel] to the Normal position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Normal position.

 

(    )         Adjust a Square Wave generator, using a Frequency Counter, for a 1000 Hz output.

 

(    )         Connect the Square Wave generator output to the [front panel] Horizontal input.

 

(    )         Adjust a Sine Wave generator, using a Frequency Counter, for a 1000 Hz output.

 

(    )         Connect the Sine Wave generator output to the [front panel] Vertical input.

 

(    )  (    )₁         Set the HORIZONTAL ATTENUATOR switch to the AC X 10 position.

 

(    )  (    )₂         Adjust the Square Wave generator output for a six graticule peek-to-peek signal.

 

(    )  (    )₃         Adjust the X 10 HORIZONTAL Input trimmer (C15) [right side panel, top front hole] until a correctly compensated square wave is obtained.

 

(    )  (    )₄         Set the HORIZONTAL ATTENUATOR switch to the AC X 100 position.

 

(    )  (    )₅         Adjust the Square Wave generator output for a six graticule peek-to-peek signal.

 

(    )  (    )₆         Adjust the X 100 HORIZONTAL Input trimmer (C17) [right side panel, top rear hole] until a correctly compensated square wave is obtained.

 

(    )         Repeat the above six * steps as necessary until, no further trimmer adjustments are required.

 

(    )         Disconnect all inputs from the front panel.

 

* * * * * * *

HORIZONTAL BEAM POSITIONING

 

(    )         Adjust the instrument for a trace.

 

(    )         Adjust the HORIZONTAL CENTERING control (R42) until the pointer is centered between the two arrows marked on the front panel.

 

(    )         Adjust the HORIZONTAL BEAM control (R76) [right side panel, bottom hole] until the trace is centered horizontally on the graticule.

 

* * * * * * *

VERTICAL BEAM POSITIONING

 

(    )         Adjust the instrument for a trace.

 

(    )         Adjust the VERTICAL CENTERING control (R13) until the pointer is centered between the two arrows marked on the front panel.

 

(    )         Adjust the VERTICAL BEAM control (R69) [left side panel, bottom hole] until the beam is centered vertically on the graticule.

 

* * * * * * *

FINAL ADJUSTMENTS

 

(    )         Set the VERTICAL switch [rear panel] to the Normal position.

 

(    )         Set the HORIZONTAL switch [rear panel] to the Normal position.

 

(    )         Adjust the FOCUS control (R56) to the full counter-clockwise to the OFF position.

 

(    )         Disconnect all wires and test leads from both the front and rear binding posts.

 

(    )         Disconnect the line cord from the AC power lines.

 

(    )         Calibration procedure is complete.