A D J U S T M E N T
Observe the following before making
adjustments
The oscilloscope is factory adjusted prior to shipment.
If readjustment becomes necessary, the following points
should be observed.
1. Check the power supply for correct voltage.
2. For adjustments, use a well insulated screwdriver.
3. Before marking adjustments, be sure to turn on the
power and wait until the unit is stabilized.
4. For adjustments, follow the procedures described
below.
5. If special test instruments are required for adjust-
ments, contact Trio's service station.
Adjustment of Power Supply and
CRT
Circuits
1. Adjustment of low power voltage (Fig. 39).
Adjust VR309 so that 195V appears on the No. 1 pin
of the connector on the same circuit board.
Next, check that voltages on No. 2, 3 and 5 pins of
P204 are + 5V, — 1 0 V and + 1 0 V , respectively.
2. Adjustment of high power voltage (Fig. 39).
* Connect a DC voltmeter of high input impedance
(more than 10OM-ohm) to the CRT socket at No. 1 ,
7 or 14 pin.
* Adjust V R 3 0 6 to obtain a high voltage of — 1.9 kV.
3. Intensity adjustment (Fig. 39).
* Pull the PULL AUTO knob to display a trace on
CRT.
* Adjust VR307 so that the trace disappears at
9 ~ 1 1 o'clock position of the brightness adjust-
ment knob.
4. Blanking voltage adjustment (Fig. 39).
Adjust TC302 so that the brightness at the sweep
starting point is the same as the brightness at other
points (SWEEP TIME/DIV in 0.5,u position).
Finally, adjust the spot with FOCUS and ASTIG.
5. CRT trace angle adjustment.
Adjust the T R A C E ROTATION (front panel) until the
trace is aligned with the horizontal line marked on the
CRT scale.
Adjustment of Vertical Circuit
1. CRT Center adjustment (Fig. 40).
With the terminals TP101 and T P 1 0 2 shorted, adjust
V R 1 0 5 until the trace comes in the center of CRT.
CRT.
2. V A R I A B L E ATT DC B A L adjustment
* Turn the vertical attenuator V A R I A B L E (6) [(9) for
CH2] fully counterclockwise.
* Turn the * POSITION (1) [(12) for CH2] until the
trace is centered on the scale.
* Turn the V A R I A B L E fully clockwise. If, at this time,
the trace shifts is position, adjust the DC B A L (2)
[(13) for CH2] until the trace is positioned on the
center horizontal line of the scale.
* Repeat stepe (2), (3) and (4) until the trace remains
stationary even when THE V A R I A B L E (6) is turned.
3. STEP ATT DC BAL Adjustment (Fig. 40).
* Turn the y POSITION (1) [(12) for CH2] until the
trace is centered on the scale at 10 mV range
of VOLTS/DIV.
* Next, turn the VOLTS/DIV to 20 mV range. If, at
this time, the trace shifts is position, adjust the
VR105 [VR109 for CH2].
* Perform the same adjustment at the 50 mV range.
For adjustment at 50 mV range, use V R 1 0 6
[VR108 for CH2].
Fig. 39.
Calibretion diagram,power supply board.
Fig. 40 .
Calibration diagram,vertical amplifier boad.
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