56/ Inch VGA Colour Monitor (CD10012XX)

Transcription

1 56/ INCH VGA COLOUR MONITOR (CD00XX) Contents 56/ Inch VGA Colour Monitor (CD00XX) Chapter 5. INTRODUCTION DSCRIPTION OF OPRATION INSTALLATION MCHANICAL ASSMBLY ST-UP AND OPRATION CIRCUIT DSCRIPTION GNRAL Colour Picture Tube RGB Video Amplifier/Tubebase Switch Mode Power Supply Hori. and Vert. Sync Polarity Circuit Horiontal Deflection Circuit Diode Modulator Vertical Deflection Circuit RROR CODS AND DIAGNOSTICS LVL 0 DIAGNOSTICS LVL DIAGNOSTICS Linearity Test Colour Blocks B/W Blocks Contrast Beep RROR RPORTING STRAPPING FUSS MONITOR DISASSMBLY Safety Removal of the Top Cover Removal of the CRT Reassembly of the CRT i OCTOBR 999

2 56/ INCH VGA COLOUR MONITOR (CD00XX) Removal of the Deflection & RGB Video Amp/Tubebase PCB's COMPONNT LAYOUT DIAGRAMS Deflection PCB PSU PCB Tubebase PCB (Front View) Tubebase PCB (Rear View) ST-UP AND ADJUSTMNTS Test quipment Set-up of the Character Generator Adjustments Supply Voltage (+89 Vdc) Adjustment Warm Up Horiontal Frequency Adjustment Vertical Hold Horiontal Phase/Position W Correction Horiontal Linearity Horiontal Width Vertical Linearity Set Height (480 Lines) MOD Vertical Shift Set Height (400 Lines) MOD Set Height (50 Lines) MOD Focus Cut-Off (Black Level), G and White Balance Adjustment TROUBLSHOOTING Tools and quipment Safety Guidelines X-Ray Precaution Shock Haard Critical Components No Raster Low or Loss of R, G or B, Raster OK Abnormal Video on CRT Screen - Too Bright - Too Dark No Blanking, Visible Retrace Line on Background Raster No Synchroniation, Horiontal and Vertical Abnormal Vertical Height in 480 Line Mode Vertical Mode W Pincushion Distortion Failure Poor Focus Failure of Switched Mode Power Supply OSCILLOSCOP WAVFORMS CONNCTOR ASSIGNMNT Video and Sync Connector Power Input Connector SCHMATIC DIAGRAMS OCTOBR ii

3 56/ INCH VGA COLOUR MONITOR (CD00XX) Contents Chapter 5. 56/ Inch VGA Colour Monitor (CD00XX) INTRODUCTION This chapter describes the 0 Inch VGA Colour Monitor used on NCR 56/5870 Automatic Teller Machines (ATMs). The monitor is a self contained replaceable unit capable of displaying computer generated graphics and text. 5.- OCTOBR 999

4 56/ INCH VGA COLOUR MONITOR (CD00XX) DSCRIPTION OF OPRATION The high resolution colour monitor, model operates as a VGA compatible video display and is suitable for use with interactive video applications to display computer generated texts and graphics. It drives a high resolution colour picture tube with a non-glare dark glass screen formatted as dot trios on 0.8 mm (0.0 in) pitch. The CRT is preassembled with a yoke which is factory adjusted for purity and convergence, therefore, no adjustment is provided or necessary for field installation. Separate Red, Green, Blue (R, G, B) analogue signals are required as data input and separate Horiontal (H) and Vertical (V) synchroniing pulses are needed to drive the horiontal and vertical circuits of the monitor. The synchronising pulses are at TTL level. The monitor will automatically sense positive and negative polarities of both H and V sync. pulses in order to display the following three modes or display formats: Resolution Sync Polarity Hor. Vert. Mode 640 (H) x 400 (V) neg. pos. Mode 640 (H) x 50 (V) pos. neg. Mode 640 (H) x 480 (V) neg. neg. The monitor runs at the horiontal line rate of.5 kh and a vertical rate of 60 H or 70 H depending on the mode chosen. It is a self powered unit which features an Automatic Mains Selector (AVS) compatible with 50 H and 60 H mains frequencies. The AVS is located internally on the Power Supply Unit (PSU) Printed Circuit Board (PCB) (which contains the Switch Mode Power Supply (SMPS)), and is capable of operating on two mains frequency ranges, these being either 0 VRMS (88 Vac - Vac) and 0 VRMS (76 Vac - 76 Vac). INSTALLATION The illustration below shows an exploded view of the assembly of the monitor. MCHANICAL ASSMBLY The monitor is assembled in a metal box and consists of the following components:- A 0 inch colour CRT with the pre-assembled purity and convergence aligned scan yoke The PSU PCB mounted on the right hand side of the metal work as viewed from the front of the monitor The wedge shaped Deflection PCB contains the sync. polarity sensor circuit and both vertical and horiontal scan generating circuits (including the -W diode modulator). This panel is mounted on the left hand side of the metal work as viewed from the rear of the monitor The RGB Video amp./tubebase PCB contains the RGB video amplification circuits as well as the tube base circuitry, this PCB is mounted on the CRT tubebase OCTOBR

5 VR TR L5 L6 IC VR4 VR5 VR6 VR VR9 VR8 CN IC IC VR VR R0 A F C6 TR8 R R4 R R8 R40 D4 R4 R7 LP R C7 R44 R5 R46 R6 L R4 LP C LP C0 C8 D C9 FOCUS TP COM TR0 IC5 J 0 T CN4 D8 D6 TR6 D0 IC4 D4 D D5 D J 56/ INCH VGA COLOUR MONITOR (CD00XX) The PC Core video and sync. input to the monitor is applied via the 5- way D-type connector (CN9), mounted on the rear metal work. NUTRO LINA TRRA CIS MD/P-00 D56 D55 D54 C9 VR D9 D 0 NOT MAINS ISOLATD CA & G - CIS MD0/P-00 SW CA & G CIS MD0/D-00 TR0 VR R45 R4 R9 TR9 R4 G D F H B C VR7 CN CNV TR TR CN HT CRT SCAN COILS LH SID PANL DFLCTION pcb TUBBAS MAIN CHASSIS 5-WAY CONN HANDL IC CONN. CRT BRACKT TOP COVR PSU pcb RH SID PANL ST-UP AND OPRATION The monitor is installed in the ATM. A mains voltage is applied to the IC connector at the rear of the unit. The RGB video and H. and V. Sync. signals from the ATM are applied to the monitor through the 5-way D-type connector, both connector screw locks are then locked into place by using a screwdriver. With an appropriate trimming tool adjust the brightness and contrast controls to give an adequately illuminated display. As the monitor is factory adjusted, it should not require any further adjustments. 5.- OCTOBR 999

6 56/ INCH VGA COLOUR MONITOR (CD00XX) CIRCUIT DSCRIPTION GNRAL The monitor comprises a 0 Inch Colour CRT housed in a metal box with the electronic circuitry mounted on three printed circuit boards, namely: The PSU PCB contains the SMPS and automatic voltage sensor The CRT Tubebase PCB contains the RGB Video Amplifier and the tubebase drive circuitry The Deflection PCB which contains the SMPS circuit and the horiontal and vertical sync. polarity sensors, horiontal and vertical deflection circuits and the diode modulator circuit for -W pincushion correction. The illustration below is a simplified block diagram of the monitor. The principle parts of the block diagram are: RGB Video Amplifier SMPS Horiontal Deflection Circuit -W Diode Modulator Vertical Deflection Circuit. Colour Picture Tube A high resolution 0 inch CRT is used for this monitor. It is a shadow mask type with in-line guns and a triad configuration of the shadow mask holes and the phosphor trio dots on the screen. The deflection unit and the tube are matched into a self-aligned package. The anode voltage HT is 0 kv while the focus voltage Vg, applied on G, can be from 5. kv to 6. kv. Screen grid G voltage, Vg, of approximately 550 V is applied to G for the correct R, G, B cut off levels. This voltage is derived from a potential divider network connected to the T supply to obtain a stable voltage with respect to the cathodes and G under all load conditions. G is used for brightness control and for horiontal and vertical blanking. Beam current limiting is applied to the CRT circuit via the RGB video processing device IC0 (LM0). The cathodes are driven from the RGB amplifiers and the heater voltage of 6. V RMS, derived from the line output transformer, is applied to the filament of the tube. OCTOBR

7 56/ INCH VGA COLOUR MONITOR (CD00XX) B G R CN0 5 RGB Gain Adjustment VR0, VR0, VR0 Clamp Video Pre-amplifier IC0 Contrast Input & BCL Contrast BCL Video Cascode Outputs R TR-TR4 G TR7-TR8 B TR9-TR0 P R G B Black Level Adjustment Presets R VR05, G VR06 B VR04 89V V 0 Vdc H A T R S G G F O CU S HT 5kV DGUASS COIL VGA Video Input CN9 89V V 0V HTRS G ST HIGHT CN VR6 VR4 VR5 TR TR4/5 H. SYNC SYNC POLARITY SNSOR IC 74HCT86 V. SYNC VR 480 V. SYNC HORIZONTAL TIMBAS IC8 LM9.5 kh HOR. FRQ. 7V VRTICAL TIMBAS & DRIV IC6 TDA675 PLL FLYBACK PULS VR7 HORIZONTAL DRIV TR5 & T VRT. LIN VRT. SHIFT Flyback Pulse SCAN COILS HOR. PHAS VR0 R8 CN5 HORIZONTAL OUTPUT TR -W TRAP VR8 VR6 -W MOD. IC7 TDA845 TR6,TR, TR, T -W W PIN ID VR5 T H VR7 LIN & FILD BLANKING BRIGHT. VR0 C57 HORIZ. OUTPUT TXFMR T CONTRAST VR9 BCL CLAMP CONT. Flyback Pulse CN8 FAN -ive 5 4 CN LV Vdc Vdc 89Vdc CN7 0/40 Vac ~ MAINS FILTR COMPONNTS PSU pcb AVS D45 D48 PVM RGULATOR PWM SMPS IC9 TA09 & TXFMR T4 P4 P P5 P P Flyback Pulse -ve 89Vdc Vdc Vdc CN4 VR DC ADJ PSU RGB Video Amplifier/Tubebase Analogue RGB signals of 0.7 V peak-to-peak level are applied to pins, and respectively, of the 5 pin high density D-type connector, CN9. The RGB signals are then fed to IC0 (LM0) though CN0 pins 5, and respectively. The input impedance for the RGB signals is 75 ohm given by VR0 and R04, VR0 and R05, VR0 and R06, each preset resistor controlling the overall gain of its respective amplifier. IC0 RGB input pins 9, 6 and 4 contain three clamp gated transistor circuits TR0, TR0 and TR0 which allow the monitor to display a brightness level when CN9 (5 way D-type connector) is disconnected. The LM0 (IC0) is a wideband video amplifier device containing three matched video amplifiers, each video amplifier containing a gain set or Drive node for setting maximum video channel gain. xternal HF compensation to this IC being applied to pins 8, and 7. Further features of this IC being three gated differential input black level clamp comparators for brightness control and three 5.-5 OCTOBR 999

8 56/ INCH VGA COLOUR MONITOR (CD00XX) matched attenuator circuits for contrast settings. The contrast dc voltage being applied externally from the Deflection PCB Contrast Control to pin of IC0 via R0. Beam current limiting from the Deflection PCB line output transformer T is also fed to IC0 via TR05, TR9 and associated circuitry providing pin (Contrast Control input) with an interactive pull down. The low impedance RGB output drives from IC0 are fed to their respective CRT cathodes via three video amplifier drive circuits configured in cascode mode, these being as follows: TR, TR4 and associated circuitry providing the R video cascode amplifier drive TR7, TR8 and associated circuitry providing the G video cascode amplifier drive TR09, TR0 and associated circuitry providing the B video cascode amplifier drive. The three identical video cascode amplifiers for the R, G and B signals are developed with a maximum output swing of 50 V peak-to-peak black to white to drive the CRT cathodes. The supply voltage of 89 Vdc for the RGB video output stage is obtained from the Deflection PCB. ach amplifier stage contains a Black level adjustment preset (VR05-R, VR06-G and VR04-B) with a 0 V shift adjustment capability to its respective cathode. One side of the presets is taken to an externally supplied 0 Vdc through a 0 k ohm pull up resistor to provide the black level range setting. R70 sets the correct voltage across the heaters at the given current. Switch Mode Power Supply The monitor employs a Switch Mode Power Supply (SMPS) located on the PSU PCB to generate three primary dc supplies namely: +89 Vdc for the horiontal deflection circuit + Vdc for the vertical deflection and -W correction circuits + Vdc for the small signal circuits. The SMPS uses a current mode switching power supply control circuit IC9 (TA09) and associated components which offers the following main features: High stability regulation loop Automatic input voltage feed-forward in discontinuous mode flyback Current limitation Full overload and short circuit protection Thermal protection Synchronisation capability with internal PLL. The monitor features an Automatic mains Voltage Selector (AVS) compatible with 50 H and 60 H mains frequencies. The AVS is capable of operating on two mains frequency ranges, these being either 0 VRMS (88 Vac - Vac) and 0 VRMS (76 Vac - 76 Vac). Mains voltage applied through the mains RFI suppression filter is full wave rectified by diodes D45 - D48, and filtered accordingly by C75 and C76. Start-up voltage to IC9 pins and is applied via R9 and R00. OCTOBR

9 56/ INCH VGA COLOUR MONITOR (CD00XX) The power switch transistor TR0. is directly driven from pin of IC9 through the base resistor R90. R9/D9 network is used as a damping circuit and the dv/dt circuit is formed by C74, R95 and D44. The voltage developed across R94 is fed back to IC9 via R84 and is used for current mode control and overload protection. D49 and D54 provide protection against over dissipation of R94 in the event of TR0 failure. The switch mode transformer T4 winding (-5) provides the supply voltage of IC9 through the rectifier filter network of D8 and C7. The secondary voltage stability and adjustment of the 89 Vdc is provided by sourcing the voltage from the -5 winding of T4 and feeding the rectified voltage through D50, C70 network to pin 6 of IC9. VR (ST B+) adjusts the 89 Vdc output. The winding -5 of T4 also provides the demagnetisation sensing of T4 which is applied to pin 5 of IC9 through R89. The demagnetisation circuit within IC9 disables any new conduction cycle of the transistor TR0 as long as the core is not completely demagnetised. To prevent the switching characteristics of the power supply giving rise to interference on the screen, the power supply is synchronised to the horiontal frequency of.5 kh by applying a horiontal flyback pulse from a single turn around the core of Line Output Transformer (LOPTx) T to pin 7 of IC9. The PLL output (pin 8) supplies a correction current to pin 9 through an external resistor R8 so as to maintain the oscillator at the correct frequency. R79, C7 form the RC network to determine the frequency of the oscillator of IC9. The 89 Vdc rail is obtained from the secondary winding 4-6, through rectifier and filter network of D6, L, C6 and C6. The Vdc is provided by the rectifier and filter network of D5, L, C60 and C58. A Vdc rail is obtained through rectifier and filter network D4, L, C6 and C59. Dual PTC resistor, PTC, provides a decreasing ac magnetising current through the degauss coil (mounted on the CRT) after switch on. The device is suitable for either 5 Vac or 40 Vac operation. At power switch on, the PTC resistor causes a diminishing 50 H/60 H degaussing current which removes remnant magnetism from the CRT. The second part of the PTC will keep the first hot. Residual current in the degaussing coil is minimised in this way, otherwise a slight picture wobble would remain. Hori. and Vert. Sync Polarity Circuit IC (74HCT86) works as a hori. and vert. sync polarity sensor. The device is a high speed C-MOS TTL compatible input 4-gate X-OR chip, all its external inputs from CN are flashover protected by diodes to ground or a 5. V rail. Hori. sync output from pin 6 remains negative with either negative or positive input hori. sync from the PC Core through CN. Similarly, the vert. sync output from pin remains positive independent of the sync polarity that PC Core feeds in. The PC Core can supply three possible mode settings of sync. which can effect the ST HIGHT circuit, these being, 480 lines (mode ), 400 lines (mode ) or 50 lines (mode ). The latter two modes requiring the addition of VR4 or VR6 being added in parallel with VR5 circuit. This requires the gating of the appropriate transistor TR4 or TR, these being also controlled by IC OCTOBR 999

10 56/ INCH VGA COLOUR MONITOR (CD00XX) The sync. output on pin changes from positive to negative when the input hori. sync polarity is positive, this increases the positive charge on C, hence TR will now conduct enabling the 50 line height setting. To enable the 400 line height setting the sync.output on pin 8 goes positive when the input vert. sync polarity is positive, effectively discharging C, switching TR4 off and TR5 on. The RC networks R6, C and R5, C provide each of the time constants for the gating voltage. Horiontal Deflection Circuit The negative going horiontal sync. signal is applied to pin of IC8 (LM9). A phase control loop compares of the phase of the incoming hori. sync pulses with the oscillator. The free running frequency of the oscillator is set at.5 kh and adjusted by VR. A second control loop compares the phase of the oscillator and the hori. flyback pulse applied from the heater winding of the LOPTx to pin 4 (IC8) via C40, VR7 (HORIZ. PHAS), C9 and its associated integrated circuit components. The horiontal drive voltage developed at pin of IC8 is applied to the drive stage TR5 and the associated driver transformer T. The pulse switching mode between drive and output stage is a reverse polarity type to simplify, when horiontal drive transistor TR5 is conducting, the horiontal output transistor is switched off. To reduce high voltage peaks on TR5 collector D, C4 and R40 are connected across the primary of T. The Line Output stage provides the following: Line Scan current Brightness, Contrast, A (G), Focus, HT dc potentials CRT heater supply 0 Vdc rail -W pincushion correction. The horiontal drive from T driver transformer switches the output transistor TR base via R current limiting, the storage charge on TR base is removed through D0. This particular line output transistor has an internal efficiency diode that reduces dissipation in the diode modulator diodes D5 - D5. Line flyback tuning of the scan coils is performed by C46 - C49. Capacitor C50 provides the S correction (controlling symmetrical linearisation). T5 auto transformer is fitted to suitably adapt the basic LOPTx design to drive a 0 inch CRT. The horiontal scan coils (H YOK) have a saturated horiontal linearity control L9 in series with them which are adjusted to correct for asymmetrical scan non-linearities due to the resistance of the scanning circuit. C45 and R55 provide damping of the linearity control coil to avoid ringing. D5, D5 and D5 are part of the diode modulator circuit (which is described in the following sub-section). T is the modulation coil which accomplishes the modulation of the horiontal deflection current for -W raster correction. The supply voltage of 89 Vdc is decoupled by C55 prior to being connected to primary winding of the LOPTx. This LOPTx, T, incorporates a diode split winding for generating the HT of 0 kv, the unit also contains an integral bleed resistor/capacitor combination to improve HT regulation. From the bleeder resistor network two potentiometers provide the necessary focus and A (G) voltages. The bleeder resistor network also discharges the CRT after switch off (for safety and reduction of spot burn-in). OCTOBR

11 56/ INCH VGA COLOUR MONITOR (CD00XX) Two auxiliary voltages are generated by rectifying the flyback pulses sourced from T, for example, a positive rail (+0 Vdc) for the video amplifier, and a negative rail (-0 Vdc) to feed the brightness control circuit (VR0). Horiontal and vertical flyback blanking pulses are applied to the G voltage via TR7, C57 and associated components. The heater winding feeds the Video/ Tubebase PCB to supply the heater volts to the tube heater pins, a tap from this point also feeds the hori. flyback pulse to IC8 pin 4 part of the phase loop circuit. To avoid over driving the picture tube a beam current limiter is used. A correction signal is developed across R70 located at the cold end of the HT winding (pin 7 of T). This signal is proportional to the HT current and is fed via the BCL connector to the Contrast Control input of IC0 on the RGB Video/Tubebase PCB. Diode Modulator The deflection coils have been designed to obtain good raster geometry at the top and bottom edges (N-S), but in the -W direction approximately 6% correction is required. The diode-modulator circuitry provides dynamic correction by modulating the hori. scan current with a parabola at the vertical frequency rate. The adjustment of the dc working point of this -W control circuit sets the picture width. The vertical current flowing through R8 (the sense resistor) develops a sawtooth voltage across it, this signal is fed into IC7 via R74 and R6. (IC7 generates the sawtooth into a parabola). A tilt is introduced to the parabola by VR8 (-W Trapeium preset) injecting a small amount of dc current into pin of IC7. Adjustment of VR8 allows some correction of -W trapeium distortion, this being due to small inaccuracies within the scan coils. IC7 (TDA 845) is a semi-conductor device specifically designed for -W correction of displays. Output from IC7 pin 7 feeds TR6 (Inverting Amplifier) base with a parabola at field rate, the amount of parabola is controlled by the -W Pincushion control VR5. The parabola on TR6 collector is a.c. coupled to the base of TR. TR and TR (emitter follower darlington pair) effectively change the impedance of the circuit across C4. This alters the drive current into T (-W loading coil), hence, providing corrective feed currents to the Hori. Scan coils. Adjusting VR7 (WIDTH) control shifts the d.c. operating point through T. Vertical Deflection Circuit The function of this circuit is to generate a sawtooth or ramp current to be applied to the vertical yoke to produce vertical scanning in synchronism to the external synchronisation pulses applied to the monitor. This is performed by IC6, TDA 670, which incorporates the following functions: Synchronisation circuit Precision oscillator and ramp generator Power output amplifier with high current capability Flyback generator Precision blanking pulse generator Thermal shutdown protection CRT screen protection which blanks the beam current in the event of loss of vertical deflection current OCTOBR 999

12 56/ INCH VGA COLOUR MONITOR (CD00XX) Vertical negative sync pulses are applied to pin 5 of IC6 from IC via R, R and C4 network. The oscillator frequency is determined by the RC network of R8, R9 and C. A supply voltage of V is applied to pin 4 through the filter network of R8, C7 and C6. C is the flyback capacitor which connects the output of the flyback generator, pin 5 to pin which is the supply voltage of the power output stage. During the trace time the supply voltage is obtained from the main supply via D4, while during the retrace time, pin is supplied from the flyback generator. The output of the power amplifier is pin and drives the vertical windings of the yoke. Pin is the inverting input of the amplifier. The network R7, R4 defines the dc level across C5 so allowing a correct centring of the output voltage. The series network of R5 and C9 in conjunction with R4 and R7 apply, at the feedback input pin, a small part of parabola available across C5 and the AC-feedback voltage taken across R6. For the vertical shift, a dc current is injected at the cold side of the vertical coils. This is obtained by means of TR and TR4 and associated circuitry with VR6 working as the Vert. Shift. The linearity control VR0 is obtained by applying a feedback between the output of the buffer stage, pin 0 and the centre tap of capacitors C8 and C7. The latter is connected to pin 9 which is the input of the buffer stage. Vertical Height is adjusted by VR5 for the MOD 480 lines (60 H). Vertical height compensation for MOD 50 lines and MOD 400 lines, VR6 and VR4, respectively. These controls are adjusted when transistors TR and network TR4/TR5 are switched on by two of the exclusive OR gates in IC. It must be noted that VR5 MUST be adjusted first before adjusting VR4 and VR6. Vertical blanking is obtained from the output of the vertical blanking generator, pin and summed with the hori. blanking at the base of TR7. OCTOBR

13 RROR CODS AND DIAGNOSTICS LVL 0 DIAGNOSTICS There are no level 0 diagnostics. 56/ INCH VGA COLOUR MONITOR (CD00XX) LVL DIAGNOSTICS The level Graphics/Video diagnostics tests enable the monitor to be tested and calibrated. The tests available are as follows: Linearity Colour Blocks B/W Blocks Contrast Beep. With the exception of the Beep test, all the tests can be cancelled by selecting the CNCL option. Looping is only allowed on the Beep test. Linearity Test When the Linearity test is selected a full screen picture is displayed on the CRT. Colour Blocks The Colour Blocks test is used to verify the overall graphics colour quality and displays colour bars on the CRT. B/W Blocks The B/W Blocks test displays four alternate black and white blocks on the CRT. Contrast Beep The Contrast test displays a white screen and black border, and is used to set up balance, brightness and tint. The Beep test emits a beep tone. RROR RPORTING There is no error reporting applicable to the CRT. STRAPPING There is no strapping associated with the CRT. FUSS Fuse F is located just to the right of the power input connector on the rear plate and is rated at.5 A, 50 V. 5.- OCTOBR 999

14 VR TR L5 L6 IC VR4 VR5 VR6 VR VR9 VR8 CN IC IC VR VR R0 A F C6 TR8 R R4 R R8 R40 D4 R4 R7 LP R C7 R44 R5 R46 R6 L R4 LP C LP C0 C8 D C9 FOCUS TP COM TR0 D55 D56 0 IC5 J T CN4 D8 D0 VR D6 TR6 IC4 D4 D D5 D J 56/ INCH VGA COLOUR MONITOR (CD00XX) MONITOR DISASSMBLY The colour monitor assembly is shown below. The monitor is factory adjusted and tested. NUTRO LINA TRRA CIS MD/P-00 D54 C9 D9 D 0 NOT MAINS ISOLATD CA & G - CIS MD0/P-00 SW CA & G CIS MD0/D-00 TR0 VR R45 R4 R9 TR9 R4 G D F H B C VR7 CN CNV TR TR CN HT CRT SCAN COILS LH SID PANL DFLCTION pcb TUBBAS MAIN CHASSIS 5-WAY CONN HANDL IC CONN. CRT BRACKT TOP COVR PSU pcb RH SID PANL OCTOBR

15 56/ INCH VGA COLOUR MONITOR (CD00XX) Safety Read the following safety notes carefully before attempting to service the monitor. The Deflection PCB, generates extremely high voltages for the CRT, in particular: 0 kv for the final anode About 4.8 kv for VG. Great care must be taken when handling this module. WARNING The CRT anode retains a potentially lethal voltage even when the monitor is turned off. The following procedure must ALWAYS be observed prior to disconnection of the HT cap or any other task which requires the CRT to be handled:. Connect a clip lead or heavy gauge wire to the chassis ground.. Connect the other end to the shaft of a flat blade screwdriver that has an insulated handle.. Keeping well clear of both the wire and the screwdriver shaft, insert the blade of the screwdriver under the HT cap and make contact with the anode terminal. Depending on the amount of charge present on the anode, a distinct snap may be heard as the CRT discharges. 5.- OCTOBR 999

16 56/ INCH VGA COLOUR MONITOR (CD00XX) It should be noted that despite correct performance of the CRT discharge procedure, the CRT bulb capacitance can accumulate charge as the discharge stresses are relaxed. It follows, therefore, that LCTRIC SHOCK HAZARD IS VR PRSNT WHN HANDLING TH CRT. The following guidelines must always be observed: Do not dispose of the CRT by breaking the bulb unless wearing safety glasses and protective clothing If it becomes necessary to remove the CRT from its mounting within the mechanical package of the monitor, under no circumstances apply leverage to the glass bulb Never apply pressure or leverage to the tension band which may displace it from its initial position. This will minimise the implosion protection afforded by its presence. NOT: Before opening any part of the monitor, switch off the unit by removing the mains voltage cable from the IC connector. The monitor includes critical mechanical and electrical parts which are essential for X-radiation safety. Replace all critical components (marked with a! ) only with the exact replacement parts named in the Parts Identification Manual. Removal of the Top Cover The top cover is taken off by removing the 4 x Taptite screws that locate with the monitor side plates. The RHS (viewed from front) metal plate contains the Deflection PCB and is secured to the Main chassis by x Taptite screws. The CRT brackets are held in place by 8 x Taptite, 4 located either side of the monitor. Removal of the CRT. Switch off the monitor.. Remove the IC connector from the monitor, now remove the male connector retaining screws from the rear plate. The board mounted IC male connector is now free to be moved with the Deflection board.. Remove the top cover by unscrewing the 4 x Taptite screws. 4. Unscrew the x Taptite screws on the metal plate containing the mounted Deflection PCB, lie it down in a safe position by the side of the monitor. 5. Remove the Tubebase PCB, from CRT base. Remove the CRT ground wire, connected to the CRT braid, from the Tubebase PCB. 6. Disconnect the degaussing coil by removing the connector from it 7. Remove the HT cap from the anode of the CRT, MAKING SUR to discharge the anode. 8. The front plates retaining the mounted CRT are then removed by unscrewing the 8 x Taptite screws, 4 located on each side of the right and left hand plates. Make sure to hold the front plate when unscrewing. OCTOBR

17 56/ INCH VGA COLOUR MONITOR (CD00XX) 9. The front plate assembly with the CRT is placed on a bench with the CRT screen facing down, making sure to have a soft protective material between the screen and the bench to avoid damage or scratches to the CRT. 0. Remove the CRT by unscrewing the 4 x M5 hexagonal standard nuts and washers. If the four inner platform nuts are required for the replacement tube, fit them before reassembly takes place as they are required for positional adjustment of the tube. Reassembly of the CRT The CRT is reassembled by following the procedure in reverse to that described above. Removal of the Deflection & RGB Video Amp/Tubebase PCB's Since two of the PCB's are soldered together, i.e. the RGB Video amp./ Tubebase PCB, both boards are removed still attached together.. Switch off the monitor.. Remove the ac Line (Mains) IC connector from rear of the monitor.. Remove the rear plate panel mounted IC connector retaining screws, the connector should now be free to be moved with the Deflection PCB. 4. Remove the top cover. Disconnect the PSU PCB from the Deflection PCB by removing connector CN from the Deflection PCB. Remove PSU PCB from its stand offs if required, this may require unscrewing the metal plate on which it is mounted. 5. Unscrew the x Taptite screws on the metal plate containing the mounted Deflection PCB, lie it down in a safe position by the side of the monitor. Remove the Deflection PCB from the side plate by pulling the PCB away from the stand off's retaining it. 6. Remove the RGB Video amp./tubebase PCB from the CRT base. Remove the CRT ground wire connected to the CRT braid, from the RGB Video amp./tubebase PCB. 7. Remove the HT cap from the anode of the CRT MAKING SUR to discharge the anode. 8. Disconnect: the degauss lead from connector CN4 on the Deflection PCB the scan coils from connector CN5 on the Deflection PCB the sync. V & H connector from CN on the Deflection PCB the DC fan from connector CN8 on the Deflection PCB RGB input drive from connector CN0 on the RGB Video amp./tubebase PCB. The above assumes a complete PCB replacement without desoldering and that during manufacture both items will be connected together and have been tested. Replacement of the PCBs is a reversal of the procedure above OCTOBR 999

18 56/ INCH VGA COLOUR MONITOR (CD00XX) COMPONNT LAYOUT DIAGRAMS Deflection PCB OCTOBR

19 56/ INCH VGA COLOUR MONITOR (CD00XX) PSU PCB 5.-7 OCTOBR 999

20 56/ INCH VGA COLOUR MONITOR (CD00XX) Tubebase PCB (Front View) OCTOBR

21 56/ INCH VGA COLOUR MONITOR (CD00XX) Tubebase PCB (Rear View) 5.-9 OCTOBR 999

22 56/ INCH VGA COLOUR MONITOR (CD00XX) ST-UP AND ADJUSTMNTS In the event of repair and/or revision to the monitor, it is necessary to follow the adjustment procedure as described below. NOT: The adjustable parameters are to some extent interactive and it may be necessary to repeat sections of the procedure to obtain optimum results. Test quipment To carry out the adjustments, the following equipment will be required: Digital multimeter to measure up to kvdc Quantum colour character generator model 80C or PC with suitable software TV colour analyer Frequency Counter to measure the.47 kh for Hori. Freq. test Non-inductive screwdriver for hori. linearity adjustment. Insulated screwdriver for other adjustments Digital HT meter (high impedance) to measure the A control volts 5 Vac and 40 Vac 50/60 H mains source Degaussing coil. Set-up of the Character Generator The Quantum character generator is set up to obtain the following data: MOD 640 X 400 Horiontal Vertical Dots/char 8 Lines/char Tot char 00 T lines/char 45 Dispd char 80 Dispd rows Drive delay 8 Drive delay 4 Drive width Drive width 9 H KH 475 MH 5 76 Hor sync - ve Vert sync + ve MOD 640 X 50 Horiontal Vertical Dots/char 8 Lines/char Tot char 00 T lines/char 45 Dispd char 80 Dispd rows 8 Drive delay 8 Drive delay Drive width Drive width 9 H KH 475 MH 5 76 Hor sync + ve Vert sync - ve MOD 640 X 480 Horiontal Vertical OCTOBR

23 56/ INCH VGA COLOUR MONITOR (CD00XX) MOD 640 X 480 Dots/char 8 Lines/char Tot char 00 T lines/char 55 Dispd char 80 Dispd rows 9 Drive delay 8 Drive delay 40 Drive width Drive width H KH 475 MH 5 76 Hor sync - ve Vert sync - ve The three modes of operation are obtained by running the diagnostic tests for the monitor giving the appropriate displays. Test patterns required: (using the Quantum generator 80C.) Cross hatch pattern 9 vert. x 9 hor. lines Full white page or white square of approx. 65 mm x 65 mm (.77 in. x.7 in.) at centre Colour bar Full page of H characters. 5.- OCTOBR 999

24 56/ INCH VGA COLOUR MONITOR (CD00XX) Adjustments The interconnection assembly diagram below, shows all the adjustable devices and their locations on the PCB assemblies. V LIN VR0 M 400 VR4 M 50 VR6 TR M 480 VR5 C5 C0 TR5 +V DGUASS COIL C9 TR4 D5 C4 H FRQ VR DZ4 C D9 D8D7 CRT TR VR5 D8 C7 D9 IC7 -W PIN D7 -W TRAP TR VR8 TR4 R56 R04 C6 IC6 IC5 V SHIFT VR6 L9 H SHIFT T C50 C45 C DZ6 C47 DZ +89V CN CN5 D5 HOR D5 DZ5 TR TR5 IC8 C D C4 D0 D C6 VR7 TB R C H POS C4 C5 C D HTRS IC D0 CLAMP D5 C5 D9 TR7 D0 DZ7 D8 D7 DZ9 D6 C54 BCL C57 C5 VR0 G CONT C55 D VR9 D CONTRAST BRIGHTNSS SCAN COILS HT DAG ARTH TR6 TR C58 C4 C49 D5 T5 T C86 +0V C80 TUBBAS PCB VR7 WIDTH C46 C48 DFLCTION PCB CSSK CD0 - SB0-A C0 C0 C0 C CN0 VR0 VR0 VR0 BCL CN0 C C05 P IC WAY INPUT SIGNAL INPUT, VRT. & HOR. SYNC INPUTS FROM 5-WAY CONNCTOR CLAMP V L0 R C KB H 0V N/C R VR04 R4 7 R5 0 R6 R4 +89V C9 C CSSK CD0 TB0 TR0 R4 C4 C6 C4 R7 RT VR05 TR4 H L 0 C5 R45 H KR C6 R68 DAG A-G R46 IC0 TR8 R8 C5 VR06 G R L0 R40 KG R G 9 N/C SG0 R48 R69 R49 G PSU PCB CN7 C78 C8 CN4 C84 L8 PTC C8 C8 R04 R99 C77 C0 C00 IC9 R0 D00 D48 D46 R05 R96 D47 D45 R0 R00 SCR C76 -ive R79R8 C7 C65 C7 R97 R9 R84 D4 C75 D40 D54 D4 D4 D49 C69 C68 IC9 R94 R95 R78 R8 C85 VR R06 R89 C70 R87 C7 C88 R9 F-PULS CSSK - FN R86 CD0 - PS0-A R85 TR0 D44 R90 R88 R9 R9 C74 D50 C79 DGUASS C6 T4 C80 8 D6 D4 C6 F L C6 C60 D5 P4 P P R07 CN8 P C89 P5 C59 C58 L FAN OCTOBR

25 40V 0V 56/ INCH VGA COLOUR MONITOR (CD00XX) The metal plates diagram below shows the locations of the controls and the connectors. CRT IC CONN MODL/B Ser CD00XX CONTRAST SCRW LOCKS FUS 5/40Vac SIGNAL INPUT LOCKING NUTS DFLCTION PCB BLACK LVL ADJUST PSU PCB GAIN ADJUST BRIGHTNSS LIN INPUT 5-WAY INPUT CONN TUBBAS PCB FOCUS IC CONN LIN INPUT FAN SIGNAL INPUT Fig.. Rear Plate Rear Plate Fig.. Top Top View with Cover Cover Removed Removed WIDTH -W PIN CONTRAST -W TRAP H LIN BRIGHTNSS V SHIFT H POS H FRQ V LIN M 50 M 400 M 480 Fig.. Right Hand Plate and and Adjustments The monitor is powered up by applying 5 Vac or 40 Vac mains to the IC connector. Apply Cross hatch test pattern signal, MOD (640 x 480) to the 5 pin D-type connector of the monitor. 5.- OCTOBR 999

26 56/ INCH VGA COLOUR MONITOR (CD00XX) Supply Voltage (+89 Vdc) Adjustment The +89 Vdc Supply Control VR is location in the SMPS circuit on Deflection PCB. Warm Up. Remove the top cover as previously described.. Connect to a mains source and switch on the Monitor.. Connect the positive terminal of the digital multimeter to TP7 and the negative terminal to. 4. Set BRIGHTNSS and CONTRAST controls to minimum. 5. Adjust VR to give +89 Vdc ± % on the digital multimeter. The monitor is allowed to warm up for 0 minutes before making any adjustments. If the monitor is switched on from cold, then its automatic degaussing system will demagnetise the CRT. If the monitor is powered up from its warm state and has been moved around, an external degaussing is required. Set the Contrast and Brightness controls (located on the Deflection PCB) to obtain a typical display. If components have been changed that effect the display illumination then all the RGB Video amp./tubebase potentiometers will require setting to midscale. However, if no changes to the display illumination have been made then adjustment of RGB Video amp./tubebase potentiometers will not be required. Horiontal Frequency Adjustment The H. FRQ. Control VR is location on the Deflection PCB.. Connect the Frequency Counter terminals between the heater resistor R70 and.. Adjust VR until.47 kh is displayed on the Frequency Counter. On completion, remove the Freq. Counter connections. Vertical Hold This adjustment is not required because the V. Hold is automatically set by the timing components connected between pins 4 and 6 of IC6. Horiontal Phase/Position The H. POS Control VR7 is location on the Deflection PCB.. Set the Horiontal Phase/Position control (VR7) to its mechanical centre.. Adjust VR7 to have the image at the centre of the screen (see diagram below). OCTOBR

27 56/ INCH VGA COLOUR MONITOR (CD00XX) BD CB55> $ ]] "]]!# "== "]] "== -W Correction The -W PINN Correction Control VR5 and the -W TRAP Control VR8 are both location on Deflection PCB. VR5 corrects the side pincushion effect (curved or bowed edges of the display). VR8 corrects the trapeoidal effect. Adjust VR5 and VR8 for straight left and right hand sides of the picture. Horiontal Linearity The H. LIN. Control L9 is located on the Deflection PCB. Using the cross hatch pattern adjust L9 until the corresponding vertical columns of the cross hatch test pattern has (as near as possible) equal width. This is measured along the centre part of the screen. Use a non-inductive screwdriver. Horiontal Width The WIDTH Control VR7 is located on the Deflection PCB. Adjust VR7 so that the horiontal sie of the display measured along the centre of the screen (assuming that the side pincushion distortion is adjusted) is 80 mm ± mm (7.08 in. ± in.) OCTOBR 999

28 56/ INCH VGA COLOUR MONITOR (CD00XX) Vertical Linearity The V. LIN. Control VR0 is located on the Deflection PCB. nsure that MOD (640 x 480) signal is applied. VRT. LIN. control, VR0, is adjusted to obtain (as near as possible) equal heights of the horiontal rows of the cross hatch test pattern at the upper and lower halves of the display. NOT: The Vert. Lin. is interactive with Set Height (480) and Vert. Shift. Therefore, these controls may need readjustments. Set Height (480 Lines) MOD The set height (M 480) Control VR5 is located on the Deflection PCB.. Apply MOD (640 x 480) signal.. Adjust VR5 so that the vertical sie of the display, measured along the centre of the screen, is 0 mm ± mm (5. in. ± in.). Vertical Shift The V. SHIFT Control VR6 is located on the Deflection PCB. Adjust VR6 to have the display vertically (as close as possible) centred on the screen. Set Height (400 Lines) MOD The set height (M 400) Control VR4 is located on the Deflection PCB.. Apply MOD (640 x 400) signal to the monitor.. Adjust VR4 so that the vertical sie of the display measured along the centre of the screen is 0 mm ± mm (5. in. ± in.). Set Height (50 Lines) MOD The set height (M 50) Control VR6 is located on the Deflection PCB.. Apply MOD (640 x 50) signal to the monitor.. Adjust VR6 so that the vertical sie of the display measured along the centre of the screen is 0 mm ± mm (5. in. ± in.). Focus The FOCUS control is located on the top part of the LOPT T.. Apply signal with full page H characters to the monitor.. Set BRIGHTNSS and CONTRAST to typical display.. Adjust FOCUS control for the best overall focus over the entire screen. OCTOBR

29 56/ INCH VGA COLOUR MONITOR (CD00XX) Cut-Off (Black Level), G and White Balance Adjustment The SCRN GRID A Control is located at the bottom part of the LOPT T. Signal requirements: All White of about 65 x 65 mm sie at the centre of raster, mode 640 x 50 Signal input: 0.45 Vpp.. Pre-adjust, (all the preset controls are located on Video amp./tubebase PCB) VR04 - B. BLK. LVL to its mid-way travel positions VR05 - R. BLK. LVL to its mid-way travel positions VR06 - G. BLK. LVL to its mid-way travel positions VR0 - B. GAIN to its maximum travel positions VR0 - G. GAIN to its maximum travel positions VR0 - R. GAIN to its maximum travel positions.. Set BRIGHTNSS and the CONTRAST controls to minimum.. Connect the digital HT meter (high impedance) terminal to pin 7 of the CRT and and adjust G potentiometer (A/Screen grid), for 650 Vdc. 4. Adjust the BRIGHTNSS control until a raster is just visible. Depending on the tube, a predominant colour will be displayed, adjust the other two colour BLK/LVL potentiometers to give a grey raster. 5. Set the CONTRAST control to maximum, set the BRIGHTNSS control to minimum. 6. Connect an oscilloscope to TP (B), TP (G) and TP (R) cathodes in turn, adjusting the respective Gain potentiometers VR0, VR0 and VR0 to give a 8 V peak-to-peak video waveform display (black to white). 7. Set the Colour Pattern generator for Pattern X (pattern -). 8. Set the CONTRAST control to mid-position, adjust the BRIGHTNSS control until the background raster is just below visibility. 9. Using the Colour TV Analyer, adjust the GAIN potentiometers for the correct colour temperature. i.e., 900 deg. K (D9 Standard), X-Y co-ordinates are X = 0.8 and Y = Using the grey video squares of Pattern X displayed on the screen. Check the colour temperature again with Colour Analyer to 900 degrees K, then if necessary adjust the BLK/LVL potentiometers to maintain the correct colour temperature. A certain amount of interaction between GAIN and BLK/LVL potentiometers will occur. Repeat steps (9) and (0) above to compromise and get the best optimum 900 degrees K results.. Switch the Generator to the Full White page (Pattern -). Set the Brightness control so that the background raster is just extinguished and adjust Contrast to obtain 60 nits, verify with a Luminance Meter OCTOBR 999

30 56/ INCH VGA COLOUR MONITOR (CD00XX) TROUBLSHOOTING The flowcharts in this section are a guide to troubleshooting the monitor. Tools and quipment For troubleshooting and adjustment of the monitor, the following tools and equipment are required: Safety Guidelines Colour Quantum Character Generator to produce the necessary video and sync. signals. If not available, signal from the PC Core 0 Vac 50/60 mains source Digital multimeter to measure up to 000 Vdc Dual trace oscilloscope with 0: probes Non-inductive screwdriver and insulated screwdrivers for adjustments where required. WARNING Before servicing this chassis, read the X-ray radiation precautions, shock haard and critical components described below. X-Ray Precaution The monitor includes critical mechanical and electrical parts which are essential for X-radiation safety. For continued safety, replace critical components indicated in the manual only with exact replacement parts given in the parts list. Operating high voltage for this unit is 0 kv at minimum brightness. Shock Haard The high voltage at which the tube is operated may be very dangerous. The monitor is operated from the mains voltage of 5 Vac or 40 Vac. Therefore, extreme care should be taken in the servicing or adjustment of any high voltage circuit. WARNING The CRT anode retains a potentially lethal voltage even when the monitor is turned off. The HT discharge procedure detailed in the safety section under the heading ASSMBLY AND DISASSMBLY must ALWAYS be observed prior to disconnection of the HT cap or any other task which requires the CRT to be handled Caution should also be exercised when servicing or handling the PSU PCB, because of the mains voltage and the rectified voltage at capacitors C7 and C8. OCTOBR

31 56/ INCH VGA COLOUR MONITOR (CD00XX) Critical Components The monitor includes critical mechanical and electrical parts which are essential for X-radiation safety. Replace all critical components (marked with a! ) only with the exact replacement parts named in the Parts Identification Manual. No Raster Check +89 Vdc Rail + Vdc, + Vdc Rail Measure on the PSU PCB TP7, TP8 and TP9 respectively OK NG Check SMPS PCB Refer to Failure of SMPS Check HV operation & TR collector waveform Deflection PCB NG Check +89 Vdc on TP0 of T Check: Hor. Oscillator Hori. Deflection HV Circuit Check CRT Heaters NG Check 6. Vac RMS on CRT base Check R6 on Tubebase PCB OK Check CRT Heaters OK Check Screen Grid G volts approx. 650 Vdc Too Low Screen unit, G lead to Tubebase PCB, C6, R68 Tubebase PCB, LOPTx T fail OK Check +0 Vdc, +89 Vdc and + Vdc on Tubebase PCB 5.-9 OCTOBR 999

32 56/ INCH VGA COLOUR MONITOR (CD00XX) Low or Loss of R, G or B, Raster OK Check RGB input at TP5, TP6 TP6 and TP7 on Tubebase PCB NG Check for connection between PC Core and monitor OK Check Video input NG Check for clamp pulse at C09, at IC0 (LM0) TR8, IC0 pin 4. 9, 0 on Tubebase PCB Check TR06 for failure OK Check RGB at TR07, TR4, TR5 collectors on Tubebase PCB NG Check +89 V dc Check +0 V dc Check + V dc OK CRT cathode failure Abnormal Video on CRT Screen - Too Bright - Too Dark Assuming checks on RGB video input and output has been done satisfactory (see above) OK Check Brightness circuit connected to G and -0 Vdc OK NG Check T, D5, C54, R6, VR0 and blanking circuit Check G screen grid voltage setting If Vg measures incorrect: check NG Vg pot unit, C6, R68 T (LOPTx), CRT Socket CRT If Vg measures correct: check OK CRT failure OCTOBR

33 56/ INCH VGA COLOUR MONITOR (CD00XX) No Blanking, Visible Retrace Line on Background Raster Check Blanking waveform on G Tubebase PCB NG Check Horiontal flyback and Vertical flyback at R9 and R64 on the Deflection PCB NG If no Hor. flyback check connection to T (LOPTx) If no Vert. flyback check connection back to Vert. output stage OK Check Hor. and Vert. Blanking on collector of TR7 NG Check TR7 and associated components No Synchroniation, Horiontal and Vertical Horiontal Adjustable by Hori. Freq. control VR9 OK Adjust Check Hori. sync. input TP on Deflection PCB NG Check connection between PC Core and monitor OK Check Hori. sync. on TP5 on Deflection PCB OK NG Check IC, R4, C44, R4 and IC8 Check 5 Vdc on TP0, R7, D6, D8 and IC on Deflection PCB Check synchroniation of input circuit NG Check IC8 and associate components 5.- OCTOBR 999

34 56/ INCH VGA COLOUR MONITOR (CD00XX) Vertical Check Vert. sync. input pin of IC on the Deflection PCB OK NG Check connection between PC Core and monitor Check 5 V on TP0, R8, D7, D9 and IC on Deflection PCB Check Vert. sync. on pin 5 of IC6 on the Deflection PCB OK Check Vert. oscillator circuit of IC6 NG Check IC6, pins and 4 and associated components on Deflection PCB Change IC6 Abnormal Vertical Height in 480 Line Mode Check + Vdc rail Measured after R8 on Deflection PCB Low Check R8 on Deflection PCB and + Vdc on Deflection PCB OK Check Vert. mode circuit by adjusting VR5 NG Check VR5 and associated components See Vertical Mode below OK Check Vert. deflection circuit section OK NG Failure IC6 or associated components on Deflection PCB/ Vert. Deflection Yoke Re-adjust VR5 (V. Height 480 lines) OCTOBR

35 56/ INCH VGA COLOUR MONITOR (CD00XX) Vertical Mode Vertical Mode NG Failure condition To small V. Height at 400 & 50 lines Vibrating V. Height Check IC, TR, TR5 and DZ9 Readjust: VR6 (50 lines) VR4 (400 lines) - W Pincushion Distortion Failure Readjust -W PIN VR5 and -W TRAP VR8 on Deflection PCB NG No field parabola at base of TR6 check IC7 and associated components on Deflection PCB Field parabola present at TR6 base Check TR6, TR, TR, T and associated components for failure Poor Focus Readjust Focus control NG Failure: Focus control unit Focus lead CRT socket CRT 5.- OCTOBR 999

36 56/ INCH VGA COLOUR MONITOR (CD00XX) Failure of Switched Mode Power Supply Check each rail: +89 Vdc on TP7 + Vdc on TP8 + Vdc on TP9 Adjust the dc Adjust control VR for +89 Vdc YS Low or no output anywhere No + Vdc output only Check D5, L & T4 Vdc winding O/C No + Vdc output only YS Check F, L and D4 YS Switch off the monitor mains and allow capacitors to discharge. Isolate PSU by disconnecting the PSU PCB from other PCBs. Insert suitable dummy load resistor between each rail and. Next turn on the power and check the +89 Vdc appears. YS Check C55, T, TR, D5, D5 & D5 on Deflection PCB NO Check that F is O/C NO YS Check D45 - D48, C75, C76 & associated components with supply rail (TP) Check waveform TP7 TR0 collector NO Check TR0, IC9 and associated components YS Check waveform at D6 anode NO Check C58 - C6 and T4 for SC YS Check D6, T4 +89 Vdc winding - O/C OCTOBR