GE AMX-II

8,4
GENERAL ELECTRIC MEDICAL SYSTEMS AMX-il X-RAY UNIT
1-1880 SM A0654E
2. Turn the circuit breaker and standby switch to ON.
3. Depress the handswitch ROTOR button while looking into the x-ray tube window. Only the small
filament is connected, the large filament is not used in this unit. If the filament does not glow, check
for improper filament circuit or HV cable connection. The small filament is the one to the left when
viewed from the anode through the x-ray tube window.
2-3 Check X-Ray Tube Anode Rotation
1. Check that 7TB1-P1 and 7TB1-P2 are disconnected at the HV transformer, and the leads taped.
2. Depress the handswitch ROTOR button while looking into the x-ray tube window.
3. When the ROTOR button is released the anode should coast for at least 10 seconds.
The x-ray tube anode should accelerate to operating speed (3400 rpm) within the 2-1/2-second interval
before the READY light glows. If rotation does not occur, check for improper connection of the stator
cable. If there is any doubt that the rotor is at proper speed, check voltages across the stator as shown in
Chapter 7, waveforms W7 and W8.
2-4 Adjust X-Ray Tube Current (MA)
The filament power and ma regulator circuits were initially adjusted during factory test. Readjustment on
installation is required because of tolerance variations between individual controls, transformers, and
tube units.
1. Remove the jumper (with banana plugs) from terminals MA+ and MA-on panel 3.
2. Install O to 150 ma, DC milliammeter +/-1/2% accuracy with plus lead in the MA+ end and the minus
lead in the MA-.
3. Connect the 7TB1-P1 and 7TB1-P2 leads at the HV transformer. '
4. Turn the x-ray tube port up and cover with a 1/8” (3.175 mm) thick lead sheet.
5. Cover the x-ray tube unit with a lead apron or place it behind a lead screen for additional radiation
protection.
Select 50 kvp and 10 mas. Make an exposure and observe that the ma meter “kicks” up scale.
7. Connect a 0 to 150 v, iron vane type, AC voltmeter across 7TB1-XS and 7TB1-XC.
8. Select 80 kvp, 200 mas. |
9. Take an exposure and read the ma meter. Do not make more than one exposure per minute.
10. if ma is not 100, adjust 3A2R34 to obtain ma x-ray tube current +/-5%.
11. Make another exposure and read the voltage across 7TB1-XS and 7TB1-XC. Record this voltage.
A 12. For this next check and adjustment, battery must be at full charge.
With power off, locate leads at main power circuit breaker 6CB1-B (heavy lead). Remove leads from
6CB1-B and connect a 10 ohm, 100 watt adjustable resistor and shorting switch as shown in Ill. 4-11-32A
between the leads and 6CB1-B. Turn power on but DO NOT MAKE EXPOSURES. Press rotor button
only. Depress switch on device shown in Ill. 4-11-32A and read voltage on DVM and adjust resistor tap
to obtain 90 VDC + 5V. With rotor depressed, adjust 3A2R30 to obtain the filament voltage recorded
earlier. Recheck this voltage with the 10 ohm resistor shorted (switch released). If difference in
voltage is more than + 1 volt, adjust 3A2R27. Repeat checks and adjustments until change in voltage
is less than + 1V with resistor in or out. Remove switch and resistor and replace leads on 6CB1-B.
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