Microvitec Series 3 Colour Displays Monitors Service Manual

							MICROVITECSERVICE MANUALSERIES—3COLOUR DISPLAY MONITORSGP0019AA2 
						

							MICROVITEC SERVICE MANUALINTRODUCTIONThe contents of this manual are divided into several sections.W e will now look in some detail at the sections and explain how they are to be used to their best advantage.Factory Pre-set Adjustments:Some of these adjustments are very critical, not only from  an operational point but also from  a safety point. Themanufacturer recommends that you read and understand the section fully before making any adjustm ents.All pre-set adjustments are included in this section. You are given the prefix for example: Field Linearity VR312. If youare not sure of the location of any pre-set (or component) then you should refer to the section containing PCB or CRTbase panel layouts. Once you have located the pre-set, you are then told what effect the adjustment will have on thedisplay.Removal/Installation  (Mechanical  Detail):This section gives information (text and illustrated) on how to remove major service items such as: CRT, Main PCBand Tripler etc.Description and Operation:These sections will help you to understand the design concept of the Microvitec CUB Monitor. They give verydetailed descriptions of each part of the circuit. For example: Line Tim ebase. Field Timebase etc. It is very importantthat you read these sections before attempting any of the fault isolation and repair procedures.Specification:The first specification list (1431/1432) contains a full specification; subsequent lists contain only the areas that differfrom  the first list. For example: the supply is 180-265 volts, 48-64 Hz (excluding 110 volt models). This will only begiven on the first specification list. Therefore, unless otherwise stated, refer to specification 1.Circuit Diagram and Parts Listing:There are many model variants in the Microvitec CUB range and obviously it would not be practical to supply all thecircuit diagrams. We have therefore devised one circuit diagram  for the main P.C.B. assembly (includingStandard/Medium  Resolution Tube Base assembly) and a separate circuit diagram for the High Resolution TubeBase assembly. In addition there are no component values on the circuit diagrams: you should refer to the PartsListing.Component location is another problem that you may encounter. To assist you in this matter we have also includeda full P.C.B. layout. 
						

							Fault Isolation and Repair Procedure:Configured in a boxed flow chart format, it represents repetitive faults encountered by our own Service Technicians.Each fault is accompanied by a series of boxes which will ask you to check a particular part of the equipment. After youhave carried out the check a question is asked (refer to Fig. 1).From the result of the question you can then answer YES or NO.If the answer is NO (as in this case) you must move onto the next box and carry out the next check.If the answer is YES. the next box will be (refer to Fig. 2).Further into the Fault Isolation Procedure you may be asked to check a component: for example (refer to Fig. 3).In this case the best method of checking the Tripler Module would be substitution for a serviceable Tripler Module. Thiswould establish very quickly the condition of the Tripler Module, in relation to the fault.W hen all the known fault causes have been effected, the chart wil be terminated by a box reading: (refer to Fig. 4).Fig. 4If you have reached this stage you should use the circuit diagram and items of test equipment and adopt a logicalmethod of fault isolation and repair.Illustrated Parts Listing (I.P.L.)This section contains ail current cabinet designs in the Microvitec CUB monitor range. It is intended to show the servicetechnician how to gain access to the equipment for repair purposes. In addition component part numbers accompanyeach illustration; this will assist you when ordering a component part.INTERMITTENT -LINE SYNCFig. 1Fig. 2Fig. 3 
						

							TECHNICAL SPECIFICATIONSMODELS - 1431/14321 : 625 lines, 50 fields interlacedor 31 2/313 lines, 50 fields non interlacedSYSTEM2 ; 525 lines, 60 fields interlacedor 262, 263 lines. 60 fields non-interlacedother non-standard systems may be suitableconsult MICROVITEC PLC.SUPPLYNominal 180 - 265V, 40 to 64HzTIMEBASE (LINE)Pull-in range 15 to 16KHzFRAME FREQUENCY50Hz - Pull-in range 45 to 65HzPOSITIONAL ERROR+ or -3%CONVERGENCE ERROR0.6m m screen center1.6m m screen edgeEHT24KV approximatelyEHT REGULATION+ or -1KVLINE FREQUENCY15.625KHzDEGAUSINGAutomatic at switch ONBANDWIDTH18MHzRESOLUTION452(H)x585(V) elementsDOT PITCH0.64mmCRTRectangular 335.4mm  (screen diagonal) 90 deg deflection.Precision in-line gun vertical stripe screen, high voltage focusINPUTS MODEL 1431TTL compatible; 1500 ohm  R, G, B inputs link selectable,positive or negative videoMODEL 1432Linear; 0 to 4V 1500 ohm R, G, B inputs.Positive video, composite or separate line and fieldsynchronisation - each link selectable positive or negativeINPUT CONNECTOR10 pin in-line SYSTEM 25 PressacOPERATING TEMP0 to 55 deg C (max) open chassis-10 deg C to +40 deg C (max)1.POW ER CONSUMPTION65 Watts approximatelyMODELS 1441 AND 1442 14 HIGH RESOLUTIONNOTE: As models 1431 and 1432, with the following exceptions:CONVERGENCE ERROR (MAX)0.3m m screen center0.8m m screen edgeEHTApproximately  24KVBANDWIDTH18MHzRESOLUTION895(H)x585(V) elements, rectangular 333mm  (screen diagonal)Automatic degausing at switch on. High focus voltage in-line gun.90 deg. diagonal deflection, 0.31mm  dot pitch black matrixscreen with pigm ented phosphors.DOT PITCH0.31mmPOSITIONAL ERROR+ or -2%2.CONVERGENCE ERROR0.8m m screen edgeMODEL 1451NOTE: As models 1431 and 1432, with the following exceptions:RESOLUTION652(H)x585(V)DOT PITCH0.43mm3.CONVERGENCE ERROR1.2m m screen edge 
						

							MODEL 2030NOTE: As models 1431 and 1432, with the following exceptions:CONVERGENCE ERROR (MAX)0.4m m screen center1.8m m screen edgeRESOLUTION505(H)x585(V) elements, 80 characters on 6 dot, wide matrixDOT PITCH0.8mmCRTRectangular 480mm  (screen diagonal) 90 deg deflectionprecision in-line gun vertical stripe screen high voltage focus4.POW ER CONSUMPTION80 Watts approximatelyMODEL 2040NOTE: As models 1431 and 1432. with the following exceptions:RESOLUTION940(H)x705(V)DOT PITCH0.47mmPOSITIONAL ERROR+ or -4%POW ER CONSUMPTION80 Watts approximately5.CONVERGENCE ERROR1.0m m screen edge 
						

							ELECTRICAL SUPPLYW arningTHIS APPARATUS MUST BE EARTHED.ImportantThe wires in the mains lead are coloured in accordance with the following code:GREEN AND YELLOW EARTHBLUENEUTRALBROW NLIVEAs the colours of the wires in the mains lead may not correspond with the coloured markings identifying theterminals in your plug, proceed as follows:1.      EarthThe wire coloured GREEN and YELLOW must be connected to the term inal marked E or by the safety earthsymbol or coloured GREEN, or GREEN and YELLOW .2.      NeutralThe wire coloured BLUE must be connected to the terminal marked N, or coloured BLACK.3.      LiveThe wire coloured BROW N must be connected to the terminal marked ‘L’, or coloured RED.X-Ray RadiationX-rays constitute a health hazard on prolonged exposure at dose range unless adequate shielding is provided.Precautions must be exercised during servicing of display equipment to ensure that the anode voltage and othertube voltages are adjusted to the recommended values.Replace with a tube of the same type number or recommended replacement to assure continued safety.Implosion ProtectionThis tube employs integral implosion protection and must be replaced with a tube of the same type or arecommended replacement to assure continued safety.Shock HazardThe high voltage at which the tube is operated may be very dangerous. Extreme care should be taken in theservicing or adjustment of any high voltage circuit Caution must be exercised during the replacement or servicing ofthe tube since a residual electrical charge may be contained on the high voltage capacitor formed by the externaland internal conductive coating of the tube funnel. To remove any undesirable residual high voltage charges fromthe tube, bleed off the charge by shorting the anode contact button, located in the funnel of the tube, to theexternal conductive coating before handling the tube.Tube HandlingW ear heavy protective clothing, including gloves and safety goggles with side shields. Handle the tube with extremecare. Do not strike, scratch or subject the tube to more than moderate pressure. Particular care should be taken toprevent damage to the seal area. 
						

							OPERATING SAFETYW e recommend — after effecting any Service and/or replacement of any part of the monitor, or after any repair work— that the SAFETY CHECKS listed following are carried out.NoteEnsure on re-assembly that ALL earth connections are replaced SECURELY; in particular safety earths andthe P band and dag earth CRT earth connections.Important!Failure to observe the points noted could affect your own safety, the products safety and ultimately, that theuser.SAFETY CHECKSEarth Continuity Checka)       Using a suitable multimeter:Check between Dag earth on the CRT and mains plug earth pin, (safety earth connection). The readingshould be less than 470Kohm (with tube discharged).b)       Check mains earth continuity between mains plug earth pin and:1) CRT P Band2) PCB Earth pin on main chassisc)      The final assembly/housing should be checked for continuity between the mains plug earth pin and ALLexposed metalwork.NoteTests b) and c) should have a resistance of less than 0.5 ohm.High Voltage Isolation/Insulation Checksa)      On the mains supply 3 pin plug, — check between live and neutral to earth  for leakagebreakdown.This test should be made with 1.5KV to 1.6KV AC or DC equivalent.On Test1) No breakdown should occur.2) Earth leakage should be less than 6mA at 1.5KV.b)      Insulation resistance should be greater than 2Megohms at 500V DC.CAUTIONA MONITOR FAILING ANY OF THE ABOVE CHECKS MUST BE RESTORED TO SAFE W ORKINGCONDITION BEFORE BEING RETURNED TO THE USER. 
						

							SAFETY STANDARDSSAFETY AND ISOLATIONUNDER NO CIRCUMSTANCES SHOULD ANY FORM OF REPAIR OR MAINTENANCE BE ATTEMPTED BYANY PERSON OTHER THAN A QUALIFIED ENGINEER.Switched Mode Power SupplyAlthough the outputs from  the power  supply are isolated from  the incoming mains supply, the bridge rectifier andthe ontrol and regulation circuit ARE NOT isolated. Therefore, when servicing the power supply section of thechassis assembly, the SMPSU should be supplied by a MAINS ISOLATION TRANSFORMER OF AT LEAST300VA RATING.HANDLING PRECAUTIONS HTElectrical ChargesThe power supply section remains charged with respect to chassis for 30-60 seconds after switching off. Careshould be taken when handling the chassis to avoid touching this area during this time.EHT Charges ² Horizontal (Line) Output Stage/CRTBefore handling or attempting adjustment or replacement on the horizontal (line) output stage or on CRT areas —always discharge the final anode of the CRT — by using a suitable EHT probe only. Do this by connecting first toCRT dag earth coating/earth braid assembly, and then to CRT final anode/anode button poppy connector.Please NoteVery considerable electrical charges can be stored in these areas²even for lengthy periods of timeafter switch off.In the interests of your personal safety observe the precautions listed.SAFETY CRITICAL COMPONENTSComponents marked on the parts list and circuit diagram are safety approved types and they should bereplaced only  with components supplied or approved by our Service Department It is also recommended that thecomponents not marked with the safety symbol should be replaced by parts of the type originally fitted, and thisapplies particularly to those resistors which are stood off the printed circuit boards.HANDLING PRECAUTIONS ² STATIC ELECTRICAL CHARGESDepending on equipment type and model, the equipment may contain devices which may be damaged by staticelectrical charges during handling. Generally, these devices are indicated by a symbol.W hen replacing or handling these devices or PCBs containing such devices, care should be taken. Soldering ironsshould be earthed and personnel should use wrist straps earthed via a 1Mohm resistor. If the latter is notpracticable they should discharge themselves of any static electricity by touching an earthed pointStatic sensitive devices should be packed in suitable conductive containers. NoteElectrostatic discharge does not necessarily kill a component completely — more likely it will wound itMany static wounded devices will pass normal test both on site and in Service Workshops. In this respectPCBs containing such wounded devices are a major cause of no fault found problems.It pays, therefore, to cultivate static safe ways when dealing with such static sensitive equipment 
						

							______________PRESET CONTROL ADJUSTMENT______________GENERALPreset controls are initially set up at the factory and normally do not require adjustment unless a change is required inthe input configuration — for example, typically to install a different graphics adaptor card in the associated hostsystem. Details of the preset controls with their use and adjustment is described following:PRESET ADJUSTMENTSTO PROTECT AGAINST ELECTRICAL SHOCK HAZARD AND TO PROTECT THE MONITOR AGAINST SHORTCIRCUIT AND DAMAGE — USE ONLY AN INSULATED NON-METALLIC TRIMMING TOOL TO MAKE AD-JUSTMENTS TO THE PRESET CONTROLS.Care should be taken when adjusting presets. Adjust only one at a time and note carefully the effects of the adjustmentbefore proceeding on to other adjustm ents. In some cases, it may be advisable to take note of the original settingposition of the preset BEFORE adjustment in case the need arises to return to the original setting.INTERCONNECTION COMPATIBILITYOn installation and prior to preset adjustments, ensure that video and sync connections from the host system arecompatible  with:a)       The monitor.b)      The interconnecting lead assembly in use.Having determined these points are correct, proceed with the adjustments required according to the details given in theaccompanying table and descriptions following.PRESET CONTROL SETTINGS1. To set the preset controls, use a signal generating a display occupying as large a screen area as possible.For example a full page of upper case letter H would be suitable, or alternatively a suitable test card asappropriate.2.       Preset controls in the table following marked with an asterisk * may be adjusted if required.However, normally this should not be necessary, as these presets are set accurately at the factory duringmanufacture.NOTE:    A circle is employed in the screen displays illustrated following, only to demonstrate more clearly thegeometric effects of wrong settings.PRESET LOCATIONSThe physical locations of m ost of the preset controls referred to in the descriptions following are shown in theillustration contained in the Section preceding.Notable exceptions are preset controls contained on the TUBE BASE PCB assembly.The positions of these presets are indicated on the individual PCBs by appropriate ident markings. 
						

							PRESETWRONG   XRIGHT /LINE FREQUENCYFIELD FREQUENCYHEIGHTWIDTHLINE PHASE*FIELD LINEARITY*(VERTICALLINEARITY)EAST/WEST*CORRECTIONFIELD SHIFTTABLE OF PRESET ADJUSTMENTS