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6.2.7.4. Removal of switch unit and potentiometer unit
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Remove the time base unit as indicated in chapter 6.2.7.3.
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Remove the trigger source unit as indicated in chapter 6.2.7.1.
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Remove the pre-amplifier and trigger unit as indicated in chapter 6.2.7.2.
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Remove one multipole connector from the final X/Z amplifier unit.
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Remove one multipole connector from the pre-amplifier and trigger unit.
- Remove all the knobs from the front panel.
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Remove 4 star-screws, that secure the switch unit and potentiometer unit to the left and right-hand chassis
panel.
- Lift the units upwards out of the instrument.
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The switch board can be separated from the potentiometer unit by means of 4 star screws (one of them is
only attainable with a small screwdriver).
IMPORTANT:
Repair of parts on the switch unit is not recommended because special tools are required for
assembling. As
6.2.7.5. Removal of power supply EHT unit and mains transformer
- Unplug one four pole connector from the power supply. This connector i s attached to a cable that comes
from the rear plate.
- Unplug one coaxial lead on the time-base. This lead is from the BNC socket on the rear panel.
- Remove the two star screws that secure the rubber CRT socket to the rear plate (the CRT remains in position
by means of i t s supports a t the screen side).
- Remove six screws that secure the top and bottom of the rear plate to the chassis.
- Remove seven screws that secure the rear plate to the chassis. The rear plate can now be taken off.
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Remove the four star screws that secure the mains transformer to the rear plate.
- Remove - if necessary -the star screw that secures the power supply to i t s compartment. This screw is
accessible via a hole in the pre-amplifier and trigger unit.
NOTE: This screw earths the power supply. When remounting the supply, fix this screw as tighty as possible.
- Slide the unit gently out of is compartment and remove
plier unit.
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To remove the EHT unit, snap it out of the two slots of the power supply compartment. To remove the
post-accelerator connection cable first remove the time-base unit according chapter 6.2.7.3.
WARNING:
The EHT is unbreakely connected to the EHT multiplier unit. The cable can be disconnected
from the CRT. When the EHT-cable i s disconnected from the CRT the end of the cable must be
discharged immediately by shorting
Fig. 6.2a. shows you
6.2.7.6. Replacement
of thermal fuse in mains transformer
The double isolation of the instrument is achieved by the isolation properties of the mains transformer.
If the mains transformer should become too hot (for instance due to a secondary short-circuit) the isolation
layer can be damaged. In order to prevent this, a thermal fuse is incorporated in the mains transformer. If the
temperature of the transformer becomes too high, the fuse blows and the mains voltage is interrupted.
The blown fuse can be replaced by
damaged.
For this proceed
as
fuse and slide it out of its compartment within the transformer. Slide the new fuse into the compartment and
solder the wires on to the soldering tags of the transformer.
result the unit i s only available as
a
a
dummy load
for
the power supply.
new one, if you are sure that the isolation layer of the transformer is not
a
follows: Remove the rear plate with the mains transformer. Desolder the two wires of the
complete spare part.
a
if necessary -the two wires from the EHT multi-
t o the instruments earth.
it
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