1 Check Adjust Power Supply DC Levels and Ripple R946 and R952

NOTE

Review the information at the beginning of the Adjustment Procedure before starting this step.

a. Remove the High-Voltage shield (see the "HighVoltage Shield" removal procedure in Section 6) if the instrument has the Current Limit board (A19). If the instrument has the Preregulator board (A18), remove the protective shield on the bottom of the Main board (A10) to access the test point pads.

JVARNINi^

To avoid electric shock and instrument damage when checking either the Head Room Voltage or the Preregulator Output Voltage, use a digital voltmeter that is isolated from ground, since the Inverter power-supply circuitry common is at line potential.

b. Connect the digital voltmeter low lead to common (TP934). If the instrument has the Current Limit board (A19), connect the volts lead to TP952. If the instrument has the Preregulator board (A18), connect the volts lead to TP940.

c. CHECK—Reading is +4.2 V to +4.4 V for instruments having the Current Limit board. Reading is 41 V to 44 V for instruments having the Preregulator board. If the reading is within these limits, skip to part e.

As desired

Best focused display

Midrange CH 1 0.1 V

CAL detent GND

Midrange NO DLY 5 ßs

CAL detent Off (knob in)

NORM TV FIELD J-

Midrange VERT MODE INT

NOTE

The following adjustment is only applicable to instruments having the Current Limit board (A 19).

d. ADJUST—Head Room Voltage Adjust (R952) for +4.3 V if your instrument contains the Current Limit board.

Adjust for 43 V if your instrument contains the Preregulator board.

e. Disconnect the voltmeter leads.

f. Connect the digital voltmeter low lead to chassis ground (TP501) and connect the volts lead to the -8.6 V supply (TP500).

g. CHECK—Reading Is -8.64 V to -8.56 V. If the reading is within these limits, skip to part i.

n. Disconnect the test setup.

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