Microvitec Series 3 Colour Displays Monitors Service Manual

INPUT CONNECTIONS AND CUSTOMER CONTROLS 1.     T.T.L.Compatible/Linear input SelectionA.       T.T.L. compatible or linear (0 to 4V, 1500 ohm) input level options can be selected by moving 3 links: (1)TL103 R,G,B located on main PCB:position 1 corresponds with linear levelsposition 2 with T.T.L. levelsNOTE: Contrast control VR111, inoperative when position 1 is selected.2.       Synchronisation - Input OptionsA.       Sync inputs must be T.T.L. compatible, the timing of sync pulses should approximately...

5.       Customer ControlsNOTE: On D series monitors the controls listed below are located on the front of the monitor, concealedbehind a downward hinging door.A.      ON/OFF Switch(1)      Mounted rear of the monitor, allows mains to be switched on and off without switching the mainssupply off.B.       Contrast/Brilliance Adjustment (VR111)(1)      Mounted rear of main PCB, only active in T.T.L. mode, and allows video gain to be variedfrom  maximum  to minimum,  at black level.C.      Brightness...

FACTORY PRESET ADJUSTMENTSNOTE:   Certain preset adjustments can be from above or below main panel. Adjustm ents are best made onastaticdisplay, preferably a MICROVITEC test card, details of test equipment are available onapplication.1.      Set HT VR4A.       Adjusted accurately at the factory to give 124V with a dark picture on, R138/137 (right hand side) 5, andshould not be re-adjusted.W ARNING:    THIS IS A CRITICAL SAFETY ADJUSTMENT, FAILURE TO COMPLY W ITH THE ABOVE W ILLINVALIDATE THE W ARRANTY.2....

8.     Field Shift VR321A.       VR321, controls positioning of raster in field scan direction.9.      East-West Correction VR328NOTE: Some models will not require this adjustment, because east-west correction is integral on certain typesof CRT.A.       Adjustment of VR328 will achieve straight verticals on left and right hand sides of pictures.10.      FocusA.      Located on end of tripler module, set brightness control to normal viewing level, then make focusadjustment.11.      Adjust Colour...

12.    Adjust Colour Gain ControlsCAUTION: MAKE THE FOLLOW ING ADJUSTMENTS USING A DC COUPLED OSCILLOSCOPE ONLY. A.Prepare to adjust colour gain controls(1)      Disable beam current limit circuit, by removing TL901 in series with CRT heaters on tube basepanel.(2)     Provide a test pattern with peak white and black level inform ation on red, green and blue.(3)      Ensure VR111 is fully clockwise to provide maximum drive voltages to video output stages.B.       Adjust red, green and blue gain...

REMOVAL/INSTALLATION DETAILSW ARNING:    ENSURE MONITOR IS DISCONNECTED FROM MAINS ELECTRICAL SUPPLY BEFOREEFFECTING THE FOLLOW ING OPERATIONS.1.       Main PCB Removal/Installation (Fig. 1)A.      Disconnect EHT lead (1) from CRT, to ensure no charge remains on tnpler connect to chassismetalwork.B.       Discharge CRT, final anode by connecting it to CRT dag.C.       Disconnect PL201 (2), PL1 (3) and on cabinet versions PL2 (4) (if fitted) and mains plug PL3.D.     Remove tube base panel and CRT...

Removal/Installation Details Fig. 1 

CRT Removal/InstallationFig. 22.       CRT Removal/Installation (Fig. 2)A.     Effect operations 1.A. thru G., then position monitor so that the CRT is face down on two padded supportblocks.B.      Remove two earthing screws (1), then refer to the illustrated mechanical parts section and remove thebase of the monitor.C.  Remove the four nuts (2) and large washers (3) securing CRT to cabinet facia (4).D.  Carefully withdraw CRT vertically.E.  Transfer degauss coil (5) and earthing braid (6) and scan coil...

3.       Line Output Transistor (TR202) and SMPSU Output Transistor (TR2) - Removal/Installation (Fig.3)A.        Remove Transistor(1)  Remove two M3screws(1) securing transistor and heatsink to main PCB.(2)  Unsolder base and emitter connections on PC3, then withdraw transistor heatsink (4).(3}   Separate transistor from  heatsink, retaining insulating bushes (3) and mica washer (2) for refitment.B.       Install Transistor(1) Coat underside of transistor with thermally conductive heatsink compound.(2)...

4.       Tripler - Removal/Installation(Fig. 4)A.       Tripier Removal(1)   Remove EHT lead from  CRT and discharge CRT final anode to the earth braid.(2)  Unsolder the following: Lead from  line output transformer overwind (1) focus lead (2) totube base panel at the tripler end.(3)  Unsolder from  main PCB: Earth return (3) from  focus control, clamp diode earth return (4)(4)  Loosen, but do not remove tripler securing screws (5), then withdraw tripler module (6) from  mainPCB.B.      Tripler Module -...