Microvitec Series 3 Colour Displays Monitors Service Manual

LINE OUTPUT - DESCRIPTION AND OPERATION A.      LineOutput1.       L202. L203 and T202 primary, are tuned during the flyback period by C222. This lasts for 11.8/11. 1uS,on 14/20 monitors.2.        Line output transistor TR2C2, is driven directly from  the secondary winding of T201. ON current iscontrolled by R227, turn off dissipation is minimised by L204.3.        Line linearity correction is provided by L203, which is damped by C217, R230 S correction is providedby C218.4.      Field timebase +25V...

TR202 COLLECTOR with 100 to 1 scope probeB.      EHT Supply1.       23.5kV required for CRT is generated by a tripler module driven from  a 7.5kV, overwind on T203.Inductance of the transform er (between prim ary and overwind), is tuned to the 7thharmonic of the flyback frequency by tripler input capacitance and self capacitance of the overwind.2.       The breathing performance of the display is further improved by deriving a high focuspotential from  a resistive thick film/substrate potential divider...

FIELD TIMEBASE* - DESCRIPTION AND OPERATIONThe field timebase -..:• ;^   s carried out by  ;-.:2C*    2>:-.-: - --_ -. ^~~:.   s determ ined by VR307, R308 and C303.produ; ~: j  2C.S   : .:c .: -- 3:  at pin 12   - •? -  ; • .-.-;;:-   s  :?r
ved from  potential across C305 and C306 as •--••.   :-ange towards-25Vsupp .   .-j - 11-   R305 R306 and R301. W hen field scan is completed the   COuS pulse dischargesC305 and C306  ready for charging cycle to be restarted.1.       FieldLinearityA.       Sawtooth...

!C301 PIN 8 with 10 to 1 scope probe3.      HT Supply for IC301A.       Derived from  a scan rectified rail from the line output stage. C305, C306 are fed via VR306 (heightcontrol) from  scan rectified supply and 12V rail.  Proportions of current and associated time constantsR303, C301 and D301 are used to minimise picture bounce thus maintaining accurate tracking of thefield scan with line scan amplitude during CRT beam  current variations, therefore reducing picturebreathing effects.4.       Field...

IC301 PIN 4 with 10 to 1 scope probe5.       Picture GeometryA.     CRT E-W pincushion distortion is corrected by modulation of line deflection current intransductor (T202) actively driven by TR301. which is then fed from the parabolic waveform at the top ofthe S correction capacitor C311. AC gam from  the amplifying driver is used to control amount ofcorrection applied to CRT.TR301 COLLECTOR with 10 to 1 scope probe 

CRT TUBE BASE PANEL - DESCRIPTION AND OPERATION1.       CRT Tube Base Panel (Refer to fig. 1)2.        Circuit DescriptionA.      All CRT electrodes are protected by a resistor, capacitor and spark gap.(1)     Scark gaps on all electrodes (except focus) are form ed by a 1-2kV ring trap gap,positioned within CRT base socket assembly. High focus voltage has a separate 10kV spark gapcontained within tube base socket.(2)     CRT cathodes are stood off from video outputs by 220 ohm resistors, the grid 100k...