15
Subject to change without notice
B o a r d R e p l a c e m e n t
reverse order, but do not fi t the protection (screening)
shield.
10 Measure the resistance between the power socket centre
connector marked “PE” and the rear chassis using an Ohm
meter. If the resistance is less than 1 Ohm continue the
fi tting procedure. Otherwise check the protective earth
circuit, and repair it until the requirement of less than
1 Ohm between power socket PE and rear chassis is met.
11 Connect power cable to the oscilloscope and switch it on.
12 Follow the Adjustment Procedure HM303-6 in the following
order (item):
1) RV1001: Adjustment of +146 Volt supply
2) +175 Volt check
3) RV1003: Adjustment of +12 Volt supply
4) -6 Volt accuracy check
5) Y plate voltage check
13 Due to the infl uence of the supply voltages on all circuitry,
it is recommended to make a complete Performance Check
as described in this Service manual.
FC Board
1 Before removing the FC board, check that the power cable
is not connected to the oscilloscope.
– Turn the 3 variable knobs (arrow marking) from their ca-
librated detent to a position where the hexagon sockets
marked “A” - which may not have been accessible - can be
unfastened.
– Turn the 3 variable knobs (arrow marking) back to their
calibrated detent and unfasten the hexagon sockets marked
“B” which are accessible in this position.
– Remove the 3 variable knobs (now unfastened) together
with their shafts (the visible one marked “C”).
2 Remove all knobs and note that the FOCUS knob is the only
knob without marking.
3 Remove the power rod from the power switch and pull off
the red power pushbutton.
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