genius 65_80hf service manual - calibration

SERVICE MANUALCalibration

(Rev. 3) GENIUS HF6-1

6.6 .6 .6 . CALIBRATIONCALIBRATIONCALIBRATIONCALIBRATION

6.1.6 .1 .6 .1 .6 .1 . Genera lGenera lGenera lGenera l

This chapter supplies all the necessary information for setting theparameters for the X-ray tubes function.The regulation of these parameters: focusing and correction of the highvoltage kV values are discussed here below.


GENIUS HF (Rev. 3)6-2

6.2 .6 .2 .6 .2 .6 .2 . High vo l t age k V c oef f ic ient va lueHigh vo l t age k V c oef f ic ient va lueHigh vo l t age k V c oef f ic ient va lueHigh vo l t age k V c oef f ic ient va lue

If the kV value detected by an instrument outside the generator isdifferent to the set value, it can be corrected using this coefficient.Calibration of the kV is made at the manufacturer's upon the finaltesting and verified via a standard instrument.The base correction value (100) can be changed using a lower datum toreduce the value of the high voltage kV.A higher kV will increase the value.Every unit above or below 100 will effect a percentage variation to thehigh voltage kV value.

1. Via the ON key, switch on the equipment. After 5 seconds the consolewill display the data program.

2. Open the front panel of the power rack, turn the switch located onthe front of PCB 9999102700 Master Processing Unit (paragraph12.1) to the right.

3. Press a vertical anatomical selection key.

4. Press the Child key to access the configuration.

5. The following message appears on the FIP:

CONfIG ALArMDB CALiBRATE EePROM TIME ENGLISH MODIF PROG 0 PrOGRAMS ERASE

Press the key ORG 3.The FIP displays the following message:

CALIBRATE k*kV



6. Press the Reset key. The message Calibration k*kV will appear on theFIP.The value of the kV correction parameter will appear on thefluoroscopy kV display.To increase or decrease this value, press the keys >5R and Resetmin. fluoroscopy.The default value is 100. This means that the multiplying factor ofthe theoretical value of the kV is 1.With this condition, the real value of the high voltage kV is equal tothe calibration value obtained during the testing of the equipment.To verify the correspondence between the set kV values and thedetected values, connect an oscilloscope between ground and thesignal [ikv] on test point TP5 of PCB 9999192500 Converter ControlBoard (paragraph 12.1).The ratio for the reading of the reference value is 10 V = 200 kV.Perform radiography with a current value of 100 mA.If the value of the kV reading is less than 2% that of the set value,the number to input is 102.The same concept is used if the voltage value is higher.The percentage error in excess must be calculated and thispercentage detracted from 100.

EXAMPLE:Radiography data 90 kV - 100 mA - 0.8 secValue read on oscilloscope 4.65 V (ratio 10 V = 200 kV)Real kV value 93Error 3.3 %Datum to input 103.

7. To confirm the changes made, press the key M1.The changed data input will be saved on EEPROM. Confirmation ofthe save will be testified by a beep.By pressing the Aux key the changes will be cancelled.

8. Press Sturdy Build to quit the configuration program.The generator will return to operating mode and new verifications canbe made.



6.3 .6 .3 .6 .3 .6 .3 . Fi lam ent heat ing c harac t er is t ic va luesFi lam ent heat ing c harac t er is t ic va luesFi lam ent heat ing c harac t er is t ic va luesFi lam ent heat ing c harac t er is t ic va lues

These are the current values for the filament heating expressed in ampsand obtained from the filament characteristics supplied by themanufacturer of the radiogenic tube.These values must be input into the computer and are used to inform therelevant circuit to regulate the value of the filament heating current.

6.3 .1 .6 .3 .1 .6 .3 .1 .6 .3 .1 . St and-by c urrentSt and-by c urrentSt and-by c urrentSt and-by c urrent

This current value must be given for both focuses and for all the tubesinstalled.The typical stand-by current value for tubes with filament of a maximumcurrent of 5.5 A and 2.5 A.In all cases, this is the value that must be set so as not to cause an issueof high voltage current.

6.3 .2 .6 .3 .2 .6 .3 .2 .6 .3 .2 . Minim um rad iography c urrentMin im um rad iography c urrentMin im um rad iography c urrentMin im um rad iography c urrent

This value corresponds to the value of the filament current that enablesus to obtain approximate 6 mA in radiography on the small focus and25 mA in radiography for the large focus.This value is obtained from the filament heating curves given by themanufacturer of the radiogenic tube and may be adjusted during thecalibration procedure of the radiography current.

6.3 .3 .6 .3 .3 .6 .3 .3 .6 .3 .3 . Max im um rad iography c urrentMax im um rad iography c urrentMax im um rad iography c urrentMax im um rad iography c urrent

The maximum filament current in radiography is a value given by themanufacturer of the radiogenic tube.The typical value is 5.5 A.The minimum and maximum filament current value for a particularfocus is used by the computer for the calculation of the heating currentduring the radiography preparation.If one of the two values is changed after calibration is made, all thevalues obtained during said calibration are cancelled.The calibration of that particular focus and that particular tube musttherefore be repeated.Caution must be taken to ensure that the maximum filament currentvalue does not exceed 8.5 A.



6.4 .6 .4 .6 .4 .6 .4 . Fluorosc opy heat ing c a l ibrat ionFluorosc opy heat ing c a l ibrat ionFluorosc opy heat ing c a l ibrat ionFluorosc opy heat ing c a l ibrat ion

Before commencing calibration exposure, the maximum heating currentvalue must be input.This current value ranges between 2800 mA and 3400 mA for filamentswith a maximum heating current of 5.5 Amps.As explained in paragraph 6.3.1, the preheating value of the large focusmust not cause an issue of current.If this occurs, calibration must be performed otherwise it would beimpossible to bring the fluoroscopy current to the minimum value of0.5 mA.In this case, the relative alarm messages will be generated duringfluoroscopy calibration (see paragraph 10.1).The maximum kV value must also be selected from the range90 - 120 kV.


2. After opening the front panel of the power rack, turn the switchlocated on the front of 9999102700 Master Processing Unit(paragraph 12.1) to the right.





Press the key ORG 3.The FIP displays the following message:

CALIBRATE FLUORO



6. Press the key +kV to access the fluoroscopy calibration program.The FIP provides the selection of the tube on which to calibrate thefluoroscopy:

FLUORO CALIBRATIONTuBE 1

Use key +mA to select the tube to calibrate.Keys M1 and Sturdy Build are also active and have the function toconfirm or cancel the selection.

7. When key M1 is pressed, the following message appears on thefluoroscopy display:• display kV: the maximum kV value that the microprocessor

reaches during fluoroscopy calibration.It is possible to change this value (from 90 to 120) using the keys>5R (decrease) and Reset min. fluoroscopy (increase)

• display mA: the maximum heating value that the microprocessorreaches during fluoroscopy calibration.Transfer from one kV step to the next is generated by reachingthe set heating value. This value may be changed using the DSI 2key to increase, or the DS1 key to decrease.

8. When the key M1 is pressed, the word READY appears on the FIP.At this point the fluoroscopy procedure is ready to begin. Byshortcircuiting via pushbuttons or the accessory connected to pointsGTB 427 and GTB 429 exposure commences.The automatically set values are:• kV = 50 kV (value indicated by the fluoroscopy kV display)• mA = stand-by value of the small focus.When fluoroscopy starts, the mA fluoroscopy reading must bebetween 0.10 and 0.25 mA. This shows that the two focuses are at anon-emission value.The small focus heating is automatically increased and at the sametime the heating and radiogenic tube emission values are read andmemorized.The emission value is given on the fluoroscopy mA display. Once themaximum heating current value fluoroscopy is reached, the heatingvalue is automatically brought to stand-by value and the kV value to80 kV.



The above sequence is repeated and once the maximum mA valuesare reached, the kV are set to the maximum value. Fluoroscopy isautomatically stopped at the end of the last cycle and the FIPdisplays the message "FLUOROSCOPY CALIBRATION OK".Release the rays command and press the Sturdy Build button to quitthe calibration routine.

NOTE:The release of the fluoroscopy command blocks emission andconsequently blocks the heating detection procedure. The procedure isresumed at the point of interruption via the fluoroscopy command.

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6.5 .6 .5 .6 .5 .6 .5 . Radiography sm al l foc us c a l ibrat ionRadiography sm al l foc us c a l ibrat ionRadiography sm al l foc us c a l ibrat ionRadiography sm al l foc us c a l ibrat ion

The small focus calibration consists in the memorization of the datarelative to the filament heating values in function of the kV values.These data are used during the radiography preparation phase to set thefilament heating value in function of the selected kV and mA.A table containing the emission current values for the different heatingvalues and voltages is therefore necessary.To generate this table inside the memory, the interval between theminimum and maximum radiography current has been divided into 9equal parts. Radiographs with different kV values must be performed foreach one of the ten current values derived therefrom.The kV - mA couples values detected at each emission are memorized asdescribed here below.A minimum of 3 value couples must be recognized for each filamentcurrent value.This makes it possible to calculate 3 coefficients for each one of the tenfilament current values which shall be called STEPS.

WARNING:Because this is a manual calibration, data for the performance ofcalibration radiographs will be provided throughout this entire phase.It is the operator's responsibility to ensure that the limit values of theradiogenic tube's maximum load are not exceeded.

Forecast of the kV and mA values obtained in the next exposure shall bemade as per the following description. Consequently, once he hasobtained the forecasted values, the operator shall decide whether it ispossible to proceed, or, if the data risk reaching or exceeding themaximum load values, to finish the STEP.With regard to the kV value, the equipment will propose the value to beused, while the forecast of the mA emission value linked to the STEPdepends upon the value of the STEP itself.At STEP 0, the filament is heated to the minimum radiography currentvalue and the forecast value is in function of this data. Once the firstexposure with STEP 0 at 40 kV has been made, the forecast of thecurrent value for the second exposure at the same STEP at 60 kV will bean increase of 20% of the value read during the first radiography.The increase of 20% will also be valid for the successive increases of highvoltage. The forecast of current increase for the successive STEPS shallbe of 50% of the current value detected at 40 kV in the previous STEP.The calibration method described is the method for a tube whosecharacteristics are not contained in the EEprom tube library.This method is called the "manual method".If the tube to be calibrated is contained in the library, the tube's data canbe loaded and, if necessary, the basic calibration data can be changed.

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6.5 .1 .6 .5 .1 .6 .5 .1 .6 .5 .1 . Aut om at ic c a l ib ra t ionAut om at ic c a l ib ra t ionAut om at ic c a l ib ra t ionAut om at ic c a l ib ra t ion

As described above, if the tube to be calibrated has been memorized, it ispossible to effect a semi-automatic calibration of the tube.This calibration consists in adapting the basic calibration to the installedtube. Proceed with the loading of the installed tube's data as described inparagraph 5.5.3.Once this procedure has been completed, perform the followingprocedure:


2. After opening the front panel of the power rack, turn the switchlocated on the front of the PCB 9999102700 Master Processing Unit(paragraph 12.1) to the right.

3. Press a vertical selection key.

4. Press the Child key to enter configuration.



Press key ORG 3.The FIP displays the following:

CALIBRATEX-RaY



6. Press the key +mA to access the radiography calibration program.The FIP changes as follows:

X-RAY CALIBRATIONTuBE 1 SMaLL FOCUS

The tube to be calibrated can be selected using the +mA key.The focus to be calibrated can be selected using the Reset key.Press key M1 after having set the desired values.To quit this program at any time, press key Sturdy Build.

7. When key M1 is pressed, the following is displayed on the FIP:

– in correspondence to the radiography kV keys is displayed themaximum heating value used during a given focus calibrationprocedure (STEP 9). This value can be changed via theradiography kV keys (see paragraph 6.3.3)

– in correspondence to the radiography mA keys is displayed theminimum heating value used as starting point for the focuscalibration (STEP 0).This value can be changed via the radiography mA keys (seeparagraph 6.3.2)

– in correspondence to the radiography sec. keys is displayed thestand-by value for the selected focus.This value can be changed via the radiography sec. keys (seeparagraph 6.3.1)

– fluoroscopy kV display. Here is displayed the variation coefficientof the basic calibration.This coefficient has a variation interval within the range of 0.900and 1.100.This data is used as variation factor for the filament heatingvalue.If 1.000 is the basic calibration, a lower number would reducethe mA emission value, while a greater number would increasethis value

– fluoroscopy mA display. Here is displayed the parameter thatautomatically corrects the basic calibration.This data assumes two values:0 = inactive correction1 = active correction.If this condition is activated, the difference between the set mAvalue and the real mA value is calculated at the end of eachexposure.If the difference is greater than 2.5%, the calibration variationcoefficient is automatically adjusted.



8. To perform this procedure it is necessary to measure the radiographymA value.Use an mA meter connected to the "LINK" connector (after havingremoved the jumper) located above the high voltage transformer onthe PCB 8502 (paragraph 12.3).

WARNING:Under no circumstances must exposure be made without the closure ofthe "LINK" jumper.This could damage the power inverter.

Once the tube's data has been loaded in memory, perform aradiography with the following data.60 kV - 100 mA - 40 ms.The following three conditions may occur after this operation:

1. The generator is switched off by the circuit breaker.Switch on again and reduce the coefficient significantly (e.g. from1.000 to 0.900).

2. The generator is blocked by "mA Safety".– The mA readings are too low, i.e. lower than those set. In this

case increase the coefficient.– The mA readings are high, i.e. higher than those set. In this

case decrease the coefficient.

3. The generator Performs the radiography.Correct the calibration coefficient if the mA value does not liewithin the limits required (10%) performing a radiographyreleasing the prep. at each exposure and waiting for thegenerator to return automatically to the limits. Repeat this pointuntil the desired mA value is reached.Perform the radiographs with all the mA and kV values to verifythat all are within the desired tolerance limits.

9. To perform calibration of the large focus, perform the same procedureas described for the calibration of the small focus.At Point 6, select large focus.

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6.5 .2 .6 .5 .2 .6 .5 .2 .6 .5 .2 . Sm al l foc us m anual c a l ib ra t ionSm al l foc us m anual c a l ib ra t ionSm al l foc us m anual c a l ib ra t ionSm al l foc us m anual c a l ib ra t ion

The calibration procedure is as follows:





5. The following message will appear on the FIP:


Press key ORG. 3.The FIP displays the following:

CALiBRATEX-RaY

6. Press the key +mA to access the radiography calibration program.The FIP changes as follows:

X-RAY CALIBRATIONTuBE 1 SmaLL FOCUS

The tube to be calibrated can be selected using the +mA key.The focus to be calibrated can be selected using the Reset key.Press key M1 after having set the desired values.To quit this program at any time, press key Sturdy Build.



7. When key M1 is pressed, the following is displayed on the FIP:

– in correspondence to the radiography kV keys is displayed themaximum heating value used during a given focus calibrationprocedure (STEP 9). This value can be changed via theradiography kV keys (see paragraph 6.3.3).

– in correspondence to the radiography mA keys is displayed theminimum heating value used as starting point for the focuscalibration (STEP 0).This value can be changed via the radiography mA keys (seeparagraph 6.3.2).

– in correspondence to the radiography sec. keys is displayed thestand-by value for the selected focus.This value can be changed via the radiography sec. keys (seeparagraph 6.3.1).

As mentioned above, to change one of the above parameters therelative key must be pressed, bearing in consideration how muchvariation is required as follows:

– left AEC led chamber ON = variation: 1 unit

– center AEC led chamber ON = variation: 10 units

– right AEC led chamber ON = variation: 100 units.The variation of the radiography maximum or radiography minimumvalue, causes the cancellation of the previous calibration made.After having set the desired values, press the M1 key.

8. Press the key ORG 2 to memorize the new settings made or ORG 4 tocancel.

9. The STEPS will now be displayed on the FIP:

STEP 0 = 3600+000.00000 +000.00000 +000.00000

The first line of the FIP indicates the STEP number and the value ofthe minimum filament current expressed in mA (3600). When thesecond line of the FIP has the three values equal to zero, this meansthat the STEP is not calibrated and calibration must be made.The selection of the step is made via the ORG 1 (increase) and +mA(decrease) keys.



10. Once selection of the desired STEP has been made, press key M1 toconfirm.The first line of the FIP displays the following information:

STEP 0 = 3600 kV = 040 kV = 000 mA = 000010 mA 40 kV 100 ms

– STEP 0 = 3600: indicates the number of the selected step andthe filament current heating value (3.6 A) used in this STEP

– kV = 040: indicates the kV value that will be used in the nextradiography

– kV=000 mA=0000: are couples of values that will be read by thecomputer during radiography calibration and displayed in theappropriate spaces. These values are given without decimals.

It is possible to change the kV value with which to perform the nextradiography using the + and - kV keys. This change may benecessary to reduce the kW value and keep away from the maximumload value.

The second line of the FIP gives the following information:

– mA RADIOGRAPHY: this means that the circuit breaker thatcontrols the flow of current during radiography is set at athreshold of 100 mA increased by 40%. This value may bechanged up to 300 mA via radiography mA selection keys.The manual setting of the current value must be made byselecting a value close to the forecast current value.

WARNING:The selection of a high current value with respect to the real value maybe due to a kV waveform with a strong oscillation at the start. Theselection of a low current value with respect to the real value may be dueto a kV waveform with a high ripple (greater than 10%) or to theautomatic switch-off of the equipment due to the circuit breaker (LedDL21, PCB 9999103000 Safety Supervisor, paragraph 12.1).

It is useful to remember that the protection of the radiographycurrent is set as follows:

– 10 / 100 nominal mA: protected with a current of 100 mAincreased by 40%. Breaker intervention = 140 mA

– 150-200 nominal mA: protected with a current of 200 mAincreased by 40. Breaker intervention = 280 mA

– 320 nominal mA: protected with a current of 320 mA increasedby 40%. Breaker intervention = 440 mA

– 0.100 s radiography time: this time may be changed using theradiography time selection keys.

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The selection of the radiography time during calibration dependsupon the speed of the instruments used to detect the kV and mAcouple values. Using the automatic reading system of the generatorthe time of 0.1 seconds (1 tenth of a second) is optimum.For the calibration of the large focus with high voltage current valuesthat exceed 300 mA, it is preferable to reduce the exposure time to0.05 seconds because for greater times the instant current valuedecreases.As described here below, the calibration radiographs must beperformed using current values lower than 10 mA for the small focusand lower than 32 mA for the large focus. When deciding the value ofthe calibration radiography time, it is appropriate not to change thetimes of the exposures within the same STEP.

If the high speed selection key LED is lit, this means that the9000 revs. speed has been selected.During this phase the operator decides which mode to accept (high orlow speed) according to the forecasted radiography values.

At the end of radiography the state or alarm state is displayed innumeric codes on the fluoroscopy minutes numerical display.

At the end of radiography, the kV and mA values detected areassociated to the step of the kV used. A new kV value must then beselected.

11. When the kV is changed (by pressing the key ORG 3), the FIPchanges as follows:


Perform radiography with a voltage value of 60 kV.The above procedure must also be applied to this phase.

12. Press key ORG 3 to increase the kV value.The FIP changes as follows:


Perform radiography with a voltage value of 80 kV.The above procedure must also be applied to this phase.3 couples of values are memorized at this point and it is possible toproceed to the next STEP.



We recommend however, to proceed with the calibration of the STEPwith the kV values of 100, 120 and 140, as proposed automaticallyby the appliance in order to memorize a greater quantity of data andguarantee a higher precision.Confirm the data by pressing key M1.

13. The following will be displayed on the FIP:

STEP 0 = 3600 kV = 140 kV = 000 mA = 0000+AAA.AAAAA +BBB.BBBBB +CCC.CCCCC

The real kV and mA fields (indicated as zero in the figure) will, in factindicate the values measured with the last exposure before pressingthe M1 key.The second line of the FIP displays the three coefficients A, B and Cthat were calculated during the last exposure.By pressing the M1 key, the three calculated coefficients, includingtheir positive or negative sign, are memorized.A beep confirms that we are ready to proceed with the calibrationsand with another STEP.

14. The following STEP is then proposed.The procedure considered until now is valid for all STEPS through toSTEP 9.Each time we confirm the values of the coefficients calculated by thecomputer, the successive STEP will be proposed up the last which isSTEP 9.If the maximum load of the radiogenic tube does not allow all theSTEPS to be completed, this is because the maximum radiographycurrent for the filament is too high.Changing this value means the resetting of all the coefficientscalculated and the consequent total repetition of the calibrationexposures.It is not necessary to complete the calibration of all ten STEPS but,as mentioned above, the greater the volume of data memorized thehigher the precision of the emission during normal operations.As well as being influenced by the thermal state of the anode and thecathode of the radiogenic tube, the precision of the radiographycurrent value depends upon the precision of the calculations that theappliance will perform during the radiography preparation phase

NOTE:To reduce the effect due to the variation of the emission current, werecommend performing the first radiographs approximately 30 minutesafter the focus has been switched on from stand-by.

To quit the program at the end of the calibration, press the Sturdy Buildkey and set the service switch on the MPU to OFF.

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6.6 .6 .6 .6 .6 .6 .6 . Radiography large foc us c a l ibrat ionRadiography large foc us c a l ibrat ionRadiography large foc us c a l ibrat ionRadiography large foc us c a l ibrat ion

The procedure for the calibration of the large focus is more or less thesame as for the small focus.Follow the procedure as per the preceding paragraph, with the followingvariations:

1. Select the large focus when the FIP displays the selection of the focusto be calibrated.

2. The minimum emission current value at STEP 0 is not between 6 and7 mA as for the small focus but between 20 and 25 mA.This is because the heating values for a minimum value of 32 mA inradiography are calculated.

3. The default value of the radiography calibration mA is not 100 mA asfor the small focus but 300 mA.This value may be changed from 32 to 800 (1000 mA in the case ofthe Genius HF 80 kW).The circuit breaker value is the value selected on the displayincreased by 40%.

4. Special attention must be given to the forecast value so that theselection of the radiography times is such as not to cause exposureswith an overload of anodic power.This could occur for high filament current values (high STEPS).Short time exposure values are preferable for these STEPS.Preferable times are lower or equal to 0.1 s with an optimum timebeing 0.05 s.

5. If it is impossible to memorize three valid kV-mA couples with highheating values and consistent emission current variation with voltagevalues between 40 - 60 - 80 kV, the voltage value automaticallyproposed by the program can be changed using the +/- kV keys.With this possibility, the first exposure of the STEP can be performedat 40 kV (a value automatically proposed by the program), the secondat 50 kV (set manually instead of 60 kV) and the third at 60 kV.In this way the emission current variations due to increases in the kVvalues will be limited and will not exceed the 1000 mA or 1200 mAemission values that automatically block radiography.The 800 mA current is the blocking limit for the Genius 65 kWgenerator.The 1000 mA current is the blocking limit for the Genius 80 kWgenerator.



6.7 .6 .7 .6 .7 .6 .7 . Cal ibrat ion c opyCal ibrat ion c opyCal ibrat ion c opyCal ibrat ion c opy

If there are two tubes of the same characteristics connected in onegenerator, the calibration can be copied (not the parameters that arecharacteristic to the tube) from one tube to another.Proceed as follows:





5. The following message will appear on the FIP:

CONfIG ALArMDB CALiBRATE EePROM TIME ITALIANO MODIF PROG 0 PrOGRAMS ERASE

Press key ORG. 3.The FIP displays the following:

CALiBRATE COpY

6. Press the key Reset to access the data copy program.The FIP now proposes the selection of the tube from which tocopy the calibration (source) and the selection of the tube onwhich to copy the calibration (destination):

COPY SOUrCE DESTiNATION 1 1



7. Press the key +kV to change the number of the tube from which tocopy the calibration.Press the key Reset to change the number of the tube on which tocopy the calibration.Once the selection has been made confirm by pressing the key M1.

8. While the data is being copied, the FIP displays the message "PLEASEWAIT", after which the FIP displays the following:

CONfIG ALArMDB CALiBRATE EePROM TIME ITALIANO MODIF PROG 0 PrOGRAMS ERASE

9. Press Sturdy Build to quit the calibration program.



6.8 .6 .8 .6 .8 .6 .8 . Generat or regulat ion loopGenerat or regulat ion loopGenerat or regulat ion loopGenerat or regulat ion loop

After having completed the calibrations described in the aboveparagraphs, it is important to know how the generator regulation loop isset by the computer.The procedure is described here below.

The logic diagram of the 65 or 80 kW generator is given on Figure 6-1.The blocks represent the physical subdivision of the generator (seeFigure 6-3).

• Block 1This block constitutes the interface between the inverter with themains. Here there are the three-phase jumper safety switches, thecapacitors and inductors for the power supply to the DC-RAIL and toenable the transfer of power to the inverter.

• Block 2This block constitutes the power inverter and the converter controlboard PCB 9999102500.

• Block 3This block constitutes the H.V. transformer.

• Block 4This block constitutes the electronic group.This group contains:– the PCB 9999103000 supervisor card and the power supply card– the normal speed starter anode card PCB 9999103200– the inverter filament driver PCB 9999102600– the optional normal and high speed starter PCB 9999103400 /

PCB 9999103300.

• Block 5This block constitutes the principal microprocessor (MasterProcessing Unit) PCB 9999102700 and the A.E.C. PCB 9999104300.

• Block 6This block is positioned at the front of the generator and is called thegeneral terminal board (GTB). It is the interfacing block with theoutside accessories.



6.8 .1 .6 .8 .1 .6 .8 .1 .6 .8 .1 . k V regu la t ion loopk V regu la t ion loopk V regu la t ion loopk V regu la t ion loop

Refer to the Figure 6-2 for a better understanding of the description herebelow.The kV regulation loop is completely analogic.This means that the microprocessor does not enter into this regulationdirectly. It recognizes the real value of the KV and the state of thegenerator thanks to the digital signals received from the inverter.

When a preparation is required, the microprocessor prepares the signals[IRA], [IRC].It then checks that the [IPW] and the [IUX] signals are active.The kV reference value is then set under the form of an analogic signal(OKV) with a scale of 1 V dc = 20 kV.All the signals are for the external devices and the generator supervisor.

When the [OHV] signal is sent to the CCB radiography commences.From this moment until the end of the exposure, the kV control is madeby the CCB.The microprocessor waits for the [IRM] signal. If this should fail duringradiography, the state of alarm is activated and all the operating cyclesare interrupted.The same check is made on the analogic signal [IKV].When the [OHV] signal reaches the CCB, the kV ref. signal (OKV) iscompared with the real kV value.The "regulated" signal reaches a voltage - frequency converter generatingthe [FRE] signal.The [FRE] signal is the real command signal of the power devices.Before reaching the IGBT, it passes through an activation logic andfinally becomes either [GF1-4] (command of one side of the jumper) or[GF2-3] (command of the other side of the jumper).If 166kV is exceeded in output, an alarm signal blocks the inverter.



6.8 .2 .6 .8 .2 .6 .8 .2 .6 .8 .2 . m A regula t ion loopm A regu la t ion loopm A regu la t ion loopm A regu la t ion loop

Refer to the Figure 6-2 for a better understanding of the description herebelow.The mA regulation loop is completely controlled by the microprocessor.This means the microprocessor recognizes the mA emission value that atall times during exposure.The microprocessor can change the emission value by changing thefilament heating value.The measurements involved in this regulation are:

• Current measurement circuit– (ich) for high radiography current– (icm) for medium radiography current– (ifc) for fluoroscopy current.The current signal is taken from the H.V. transformer and taken tothe CCB by the J4 connector.Here, it is measured by a circuit and amplified according to thefollowing scales:– (ich): 10 V dc = 1500 mA– (icm): 10 V dc = 150 mA– (icl): 10 V dc = 10 mA.

• MPU cardA/D of the microprocessor, used to convert the analogic signal of themA to a digital signal and, D/A, to generate the reference analogicsignal of the filament heating.

• Inverter filament driver cardThis card provides for the heating of the filaments.

In order to recognize the characteristics of the tube emission, themicroprocessor must recognize the tube calibration.In this way it can calculate the value at which it must heat the filamentfor the kV-mA couple selected by the operator. The microprocessorrequires this value only for the start of the exposure and this value mustbe as near as possible to the value of the selected mA. After a fewseconds from the start of exposure the microprocessor starts to monitorthe emission mA values and consequently regulates the heating.If the heating mA value is too far from that selected (25% for low values,12.5% for high values), the microprocessor halts radiography and entersinto alarm mode. This it because it decides that regulation is no longerpossible for reaching the correct emission value and therefore achieve agood result.The alarm state may occur for two reasons:– uncalibrated tube– incorrect reading of the emission mA values caused by a malfunction

in the mA measurement loop or heating regulation loop.



Figure 6-1



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Figure 6-2



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Figure 6-3

genius 65_80hf service manual - calibration

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