Planmeca Proline CC, Technical Manual

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Chapter I - FUNCTIONAL DESCRIPTION
I-14 Planmeca Proline CC panoramic x-ray
Technical Manual
Protective earthing
In the 200 V equipments, where the mains comes in at the bottom of the column, the first earth-
ing is done there. From there it continues along the mains spiral cable to the lower fixed part,
where it is connected to the lower fixed part. In 100 V equipments the first earthing is done here.
From this point the vertical part is earthed by a separate wire. The earth wire continues also to
the upper fixed part, where it is connected to it and also to the mains filter. From this point on the
earthing wire proceeds through the rotating joint and is connected to the rotating part near the
bearing. This is the very point, where the ground of the electronics is connected to the protective
earthing. From this point goes one more earthing wire to the tube head.
When servicing the equipment always take care that all the earthing wires are properly con-
nected. If the earthing is not in order the equipment can be lethal to the user.
The microprocessor detects if the ground of the electronics is not connected to the protective
earthing (tube head not earthed) and will not start the generator, but it cannot tell if the earthing is
not connected to the mains plug.
Electronics power supply
To keep the wire count down there are only two operating voltages delivered along the cables.
One is 6VAC to the lamps and the other is an about 33 VDC voltage that is supplied to the circuit
boards. Them both have the same ground. The circuit boards have small separate switch mode
power supplies that generate from the 33 VDC the voltages needed on each circuit board. For
example the generator processor alone needs voltages of +33VDC, +15VDC, +5VDC, -5VDC
and -15VDC. The system operates normally if the 33 VDC remains between 26 VDC and 39
VDC thus allowing a good tolerance for the mains voltage variations and voltage losses in the
cables.
The layer positioning light, having such a long cable from the power supply, has a separate
ground wire not to affect the keyboard processor ground levels.
The generator circuit board needs the mains for the power stage but also two floating power sup-
plies for the control circuitry and the tube filament. Again, to save the wires the generator has a
small mains transformer on board to create these voltages from the mains.
Signals
To be able to minimize the wires two microprocessors were installed, both as near as possible to
the generator, motors and sensors. To pass all the information needed to operate the equipment
there is only one wire that connects the microprocessors together providing a serial communica-
tions channel. The keyboard/display is connected to the keyboard processor with a three wire
serial link and needs thus only five wires (actually six with double ground). The keyboard alone
should otherwise have needed 29 wires.
From the keyboard processor leaves a seven pole spiral cable down the left side of the column.
Two of these are needed for the up/down motor that couldn’t possibly be placed near to the proc-
essors. The other five wires go to the remote control box. Three of these are needed for the nor-
mal operation of the equipment and the two others provide one extra serial communications
channel to allow various kinds of new functions and equipment to be adapted to the equipment.
In the following are shortly described the signals in various interconnecting cables that can easily
be checked. The rightmost columns define the voltage range and type of the signal:
Construction and operation
D DC-voltage level
A AC-voltage level (50 or 60 Hz)
P Single pulses (sensors, relay drives etc.)
S Serial communication line (continuously pulsed)
H High frequency (over 60 Hz) switched power line