56/588X Ten Inch VGA Colour Monitor (Y0F9151)

Transcription

1 Contents 56/588X Ten Inch VGA Colour Monitor (Y0F9151) GENERAL DESCRIPTION FUNCTIONAL DESCRIPTION " CRT DEGAUSSI CIRCUIT RGB PRE-AMPLIFIER VIDEO AMPLIFIER SCAN BOARD Horiontal Deflection Circuit Diode Modulator Vertical Deflection Circuit SERVICE AIDS DIAGNOSTICS Linearity Colour Blocks B/W Blocks Contrast Beep ERROR REPORTI STRAPPI FUSES ASSEMBLY AND DISASSEMBLY Safety Removal of the Top Cover Removal of the CRT Removal of the Scan Board Removal of the Video Amplifier Board Removal of the RGB Pre-amplifier Board Removal of the Degaussing Circuit Board ADJUSTMENTS Test Equipment Set Up of the Character Generator Mode 2 (640 x 350) Mode 3 (640 x 480) Warm Up i

2 Horiontal Hold Vertical Hold Horiontal Shift Horiontal Phase Side Pin Cushion Horiontal Linearity Horiontal Width Vertical Linearity Vertical Amplitude (Mode 1) Vertical Amplitude (Mode 2) Vertical Amplitude (Mode 3) Vertical Shift Sub-brightness Focus Cut-Off (Black Level), G2 and White Balance Adjustment Overvoltage or X-Ray Radiation Protection Adjustment TROUBLESHOOTI INFO Tools and Equipment No Raster No Picture - Raster Low or Loss of R, G or B Abnormal Video on CRT - Too Bright or Too Dark No Blanking - Visible Retrace Line on the Back Raster Bad Horiontal and Vertical Synchroniation Vertical Abnormal Vertical Height in 480 Line Mode Vertical Mode Side-Pin Cushion Distortion Failure Poor Focus CONNECTOR ASSIGNMENT Video and Sync Connector Vdc Power Input Connector Vac Power Input Connector SCHEMATIC DIAGRAMS ii

3 Contents CHAPTER /588X Ten Inch VGA Colour Monitor (Y0F9151) GENERAL DESCRIPTION The 10 inch VGA colour monitor operates as a VGA compatible video display in the NCR 56/588X Automated Teller Machines (ATMs). Separate red, green and blue (RGB) analogue signals from the Terminal Control Module are input to the monitor, along with horiontal and vertical synchronisation pulses. The monitor automatically senses positive and negative polarities of both horiontal and vertical sync pulses in order to display the following three modes or display formats: Mode Resolution Sync. Polarity Horiontal Vertical (H) x 400 (V) Negative Positive (H) x 350 (V) Positive Negative (H) x 480 (V) Negative Negative The monitor operates at a horiontal line rate of 31.5 kh and a vertical rate of 60 H or 70 H depending on the mode chosen. The monitor is powered by a stabilied voltage of +24 Vdc +_ 0.2 Vdc supplied from the system power supply unit. A separate voltage of 115 Vac supplies the automatic degaussing circuit in the monitor

4 FUNCTIONAL DESCRIPTION The monitor comprises a metal enclosure containing the following components: 10" colour CRT with scan yoke Degaussing circuit board assembly RGB pre-amplifier board assembly Video amplifier board assembly Scan board assembly, comprising: Horiontal deflection circuit Vertical deflection circuit E-W diode modulator. Refer to the diagram below and the schematic diagrams on fold outs FO-1 and FO-2, at the end of this chapter, while reading the following description

5 H. SYNC. POSITIVE / NEGATIVE HOR. SYNC. SYNC. SENSOR V. SYNC. IC1 TR3 V.C. VIDEO CONNECTOR +12V RGB RGB PREAMPLIFIER B G R TR1 IC1 TR2 TR3 IC2 TR4 R G TR5 IC3 TR6 B CONTRAST 24V d.c. F1 T1.25A 250V I.C.4 +24V +12V 115V d.c. DC DEGAUSSI CIRCUIT +12V +12V +24V HORIZONTAL CONTROL IC2 HORIZONTAL DRIVER TR2 HORIZONTAL O/P TR5 FLYBACK HOR.BLANKI VA +85V RGB AMPLIFIER TR1 TR2 R +85V BLANKI CIRCUIT TR6 VERTICAL BLANKI TR3 TR4 G TR5 TR6 B MODE SWITCH TR2 MODE SWITCH TR1 VR5 350 LINES VR6 400 LINES VERTICAL SYNC +24V VERTICAL TIME BASE IC3 VR7 480 LINES HORIZONTAL OUTPUT TRANSFORMER T2 HORIZONTAL DEFLECTION CIRCUIT - 140V +24V BRIGHTNESS CIRCUIT BEAM CURRENT LIMITER TR11 - TR12 +24V E - W DIODE MODULATOR TR1 TR2 TR4 VERT. AMP. COMP. HORIZONTAL WIDTH COMP. FOCUS ( G4 ) G2 85V E.H.T. 25KV HORIZONTAL DEFLECTION WINDI ANODE KR KG KB G1 G2 G4 C.R.T. 10 in. M23JGO22XX07 VERTICAL DEFLECTION WINDI DEGAUSSI COIL

6 10" CRT The monitor uses a 10" high resolution colour CRT. The anode voltage (EHT) of the CRT is 22 kv, while the focus voltage (Vg3), applied to G3, is 6.5 kv to 7.9 kv. The screen grid voltage (Vg2), applied to G2, is 420V to 900V. The G2 voltage is derived from the horiontal deflection circuit to obtain a stable voltage with respect to each of the cathodes and screen grid (G1) under all load conditions. G1 is used for brightness control, beam current limiting and horiontal and vertical blanking. A voltage of 6.3 Vrms, derived from the deflection circuit, is applied to the heating filament. The cathodes are driven from the RGB amplifiers on the video amplifier board. DEGAUSSI CIRCUIT The degaussing circuit comprises a dual PTC resistor, a degaussing coil and a protective fuse, F1. When ac power is applied to the degaussing circuit, the PTC resistor causes a decreasing ac magnetiing current to be applied to the degaussing coil. This removes any remnant magnetism from the CRT. The second part of the PTC resistor keeps the first part hot to minimise residual current in the degaussing coil. Fuse F1 is used as a protective component against any short circuits in either the PTC resistor or the degaussing coil. RGB PRE-AMPLIFIER Analogue RGB video signals of 0.7 Vp-p are applied through pins 1, 2 and 3 respectively of the 15 pin D-type connector, to the inverters TR1, TR5 and TR3. The signal input impedance is 75 ohms, given by R10, R50 and R30, as the impedance of the inverters is about 10 kohms. Referring to the G channel only (as the R and B channels are similar), the inverted signal is fed to pin 6 of the transistor array IC3, which has a high transition frequency (typically 550 MH). The gain of the amplifier is governed by the ratio of R45 and R46 to R61 at maximum contrast. Potentiometer VR1 controls the contrast and varies the emitter current of Q1. A low impedance output signal of 2.5 Vp-p (maximum contrast) is provided at pins 10 and 14 of IC3. TR5 and IC3 both invert the signal and as a result there is no overall signal inversion. A keyed horiontal clamping pulse is applied through TR7 to the RGB preamplifier clamping output transistors TR2, TR6 and TR4 respectively for dc restoration of the output signal from IC3. The pre-amplified RGB signals are fed to the video amplifier

7 VIDEO AMPLIFIER Three identical video amplifiers for the R, G and B signals provide a maximum output swing of 45 Vp-p black to white to drive the cathodes of the CRT. Each amplifier contains a black level and a gain adjustment. The supply voltage of 85 Vdc is obtained by rectifying the positive horiontal flyback pulse from the line output transformer (LOPT), T2. Referring to the G-amplifier network, transistors TR6 (common emitter stage) and TR5 (common base stage) are connected to form a cascade circuit with relatively high input impedance, extended bandwidth and return isolation. The video signal is applied to the base of TR6 through the G GAIN adjustment trimmer VR6 which is used for white balance adjustment. A stable bias voltage of +5.1V is applied to the base of TR5 through ener diode D2. The black level for the G-gun is adjusted by altering potentiometer VR5 (G BLK LEVEL). This changes the bias of TR5 at its emitter. The overall gain of the amplifier is formed by the ratio of collector resistor R18 and the resistor on the emitter of TR6 (R20). The output signal directly drives the G-cathode through the protection resistor R17. SCAN BOARD The scan board comprises three main circuits: Horiontal deflection circuit Diode modulator Vertical deflection circuit. Horiontal Deflection Circuit The four gate EX-OR chip, IC1, operates as a horiontal and vertical sync polarity sensor. The horiontal sync output from gate D (pin 11) remains positive when the horiontal sync input signal is either positive or negative. Similarly with the vertical sync output from gate A (pin 3). R5, C1 and R4, C2 form an integrating network with a long time constant compared to the horiontal or vertical sync polarity time period. The output levels of gates B and C (pins 6 and 8 respectively) change from low to high when the horiontal or vertical sync polarity is positive; with negative sync polarity the gate outputs are low. The main functions of IC2 are: Horiontal oscillator (pins 14 and 16, VR1 and C10). Sync separator (if composite sync is applied). Two phase loops (pin 1 and pin 2). Open collector drive pulse with constant duty cycle (pin 4). The first phase loop (pin 17) compares the phase of the incoming horiontal sync pulses and the oscillator. The free running frequency of the oscillator is set at 31.5 kh and adjusted by VR1. The second phase (pins 2 and 3) compares the phase of the oscillator and the horiontal flyback pulse applied to pin 2 through R19 and R29. This loop compensates for storage time variations of the horiontal deflection transistor, TR5. VR3 adjusts the phase by injecting an additional current into the phase shifter (pin 3)

8 R23 is the collector resistor of the open collector transistor at pin 4 of IC2. The horiontal output pulse from pin 4 drives the driver circuit which consists of the driver transformer T1 and the driver transistor TR4. The driver stage operates in the non-simultaneous mode; TR4 is off when TR5 is on. R26 and C19 added across the primary winding of T1 reduce the voltage peak on TR4. The flyback tuning capacitors C25, C51 and C26 and the horiontal deflection coil are connected directly across TR5. C24 is the S-correction capacitor for symmetrical lineariation and is connected in series with the deflection coil; while asymmetrical correction is achieved with the linearity corrector L2. C27 also serves as an additional S-correction capacitor. Diodes D20 and D21 are damper diodes. L5 is the modulation coil which modulates the horiontal deflection current for the E-W raster correction. A booster capacitor, C22, is connected through a snubber network formed by L4, C23 and R28 at pin 5 of T2 to avoid ringing. The supply voltage of +24 Vdc is connected to pin 10 of the LOPT (T2) through the diode D19 and the decoupling filter network of L3 and C21. T2 incorporates a three diode unit to generate the EHT of 22 kv with low internal impedance. Two potentiometers mounted on T2 allow the focus and G2 voltage to be adjusted. A bleeder resistor is incorporated at the output of T2 (integral to the EHT lead) which acts as a pre-load on the EHT, and also discharges the CRT after switch off (for safety and to reduce spot burn-in). A high voltage capacitor, C, is connected between the EHT and ground to avoid dynamic distortion of the display at high beam currents. Several auxiliary voltages for the B+ of the video amplifier, vertical deflection circuit and the brightness control are generated by rectifying the flyback pulses sourced from T2. The CRT heater filament voltage of 6.3 Vrms is sourced from pin 2 of T2 and applied via R21 on the video amplifier. The brightness is altered by adjusting the G1 potential of the CRT, formed by R44 and VR14 and the brightness potentiometer VR13 on the scan board using a voltage source of -140 Vdc. The horiontal shift adjustment allows the usable horiontal scan to be centred at the centre of the screen. Diodes D16 and D17 rectify the scan voltage, and the resulting dc voltage, adjustable by horiontal shift potentiometer VR4, is applied to the horiontal deflection coil. To avoid damage to the picture tube, a beam current limiter is used. A correction signal, formed at the 'cold' side of the EHT winding (pin 7 of T2) and by the network of C29, R35, R36, R37 and D24 is buffered and inverted by TR11. If the beam current exceeds the maximum allowable level (approximately 300 microamps), TR12 will cease to conduct and the collector potential will go more negative. Diode D25 will also conduct and G1 will be driven so far negative that the beam current will stay at the maximum level. Variations in the EHT internal impedance, caused by beam current variations, result in picture "breathing" (picture height and width variations). This is compensated by applying a correction signal from the base of TR11 through R56 to pin 9 of IC3, for vertical height compensation, and from the emitter of TR11 to the base of TR9 via R87 for horiontal width compensation. Horiontal and vertical blanking pulses are applied to G1 through TR6. The base of TR6 is driven by horiontal flyback pulses through D15 and vertical flyback pulses through D14. A ener diode, D18, provides flashover protection

9 Diode Modulator The diode modulator corrects the pin-cushion distortion in the E-W (right-left) direction of the deflection coils by modulating the horiontal scan. It is driven by a parabolic voltage at the vertical frequency. The parabolic signal is created by integrating the vertical sawtooth signal available on the sense resistor R65. The sawtooth signal is connected to the base of TR8, coupled through R69 and R68. With the line mode changed (60/70 H), R68 is short circuited by TR7 in order to maintain the same sawtooth amplitude. TR8 and C43 integrate the signal into a parabolic shaped correction signal at the collector of TR8 which is applied to the base of TR9. Horiontal width is effected by changing the dc reference voltage at the base of TR9. Picture width stabiliation against beam current changes is made by applying the beam current dependent dc voltage to the base of TR9 through R87. Pin cushion adjustment is made by VR11 which is connected to a dc reference source derived from the resistor divider of VR12, R74 and R75. Therefore, by adjusting VR11, the horiontal width will not change as the dc level at both ends of VR12 is effectively the same. The parabolic correction signal and the dc amplitude signal are fed to the Darlington power amplifier, TR10. The supply voltage to the modulator is stabilied to +24V and filtered by R84 and C46. Vertical Deflection Circuit The vertical deflection circuit generates a sawtooth or ramp current which is applied to the vertical yoke to produce vertical scanning in synchroniation with the external sync pulses applied to the monitor. This is performed by IC3 which incorporates the following functions: Synchroniation circuit Precision oscillator and ramp generator Power output amplifier with high current capability Flyback generator Voltage regulator Precision blanking pulse generator Thermal shutdown protection CRT protection, which blanks the beam current in the event of loss of vertical deflection current. The vertical sync pulses are applied to pin 5 of IC3 from gate A of IC1, via the network formed by D6, R47, R46 and C33. The oscillator frequency is determined by the RC network of R59, VR9 and C39. The vertical hold potentiometer, VR9, adjusts the oscillator frequency. The supply voltage of +24 Vdc is applied to pin 14 through the filter network of R51 and C36. C34 is the flyback capacitor which connects the output of the flyback generator (pin 15) to pin 2 which is the supply voltage of the power output stage. During the trace time the supply voltage is obtained via D7, while during the retrace time it is obtained from the flyback generator. The output of the power amplifier (pin 1) drives the vertical windings of the yoke. Pin 12 is the inverting input of the amplifier. The network R64 and R62 defines the dc level across C42 to allow the correct centring of the output voltage. The series network of R63 and C41, in conjunction with R62 and R64, applies a small part of the parabola available across C42, and the ac-feedback voltage taken across R65, to the feedback input of pin

10 For the vertical shift, a dc current is injected at the 'cold' side of the vertical coils. This is obtained by means of a resistor divider, VR10, between the vertical supply voltage and ground. The linearity control, VR8, is obtained by applying feedback between the output of the buffer stage, pin 10, and the tapping of capacitors C37 and C38. C38 is connected to pin 9 of IC3, which is the input to the buffer stage. Vertical height is adjusted by VR7 for mode 3 (60 H). The vertical height compensation for modes 1 and 2, VR5 and VR6 respectively, are adjusted when the transistors TR2 and TR1 are switched on by output gates C and B of IC1. NOTE: VR7 must be adjusted first before adjusting VR5 and VR6. Vertical blanking is obtained from the output of the vertical blanking generator, pin 13, and is summed with the horiontal blanking at the junction of D14 and D15 to produce the blanking signal. SERVICE AIDS DIAGNOSTICS There are no Level 0 diagnostics for the CRT. The level 1 Graphics/Video diagnostic tests enable the monitor to be tested and calibrated. The tests offered 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 When the Linearity test is selected the H character is displayed in all positions on the CRT. Colour Blocks The Colour Blocks test is used to verify the overall graphic 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 The Contrast test displays a white screen and black border, and is used to set up balance, brightness and tint

11 Beep The Beep test emits a beep tone. ERROR REPORTI There is no error reporting applicable to the CRT. STRAPPI All jumpers are implemented with ero ohm resistors and should not be removed. FUSES There are two fuses on the monitor: F1 on the scan board is rated at 2.5A, 250V. F1 on the degaussing circuit board is rated at 1.25A, 250V. ASSEMBLY AND DISASSEMBLY Safety Read the following safety notes carefully before attempting to service the monitor. The scan board generates extremely high voltages for the CRT, in particular: 22 kv for the final anode 6 kv for the focus grid. Therefore great care must be taken when handling the scan board and video amplifier. WARNI 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 EHT cap or any other task which requires the CRT to be handled: 1. Connect a clip lead or heavy gauge wire to chassis ground. 2. Connect the other end of the lead to the shaft of a flat blade screwdriver that has an insulated handle

12 3. Keeping well clear of both the wire and the screwdriver shaft, insert the blade of the screwdriver under the EHT 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. 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 ELECTRIC SHOCK HAZARD IS EVER PRESENT WHEN HANDLI THE CRT. The following guidelines must also always be observed: Do not dispose of the CRT by breaking it, unless wearing safety glasses and protective clothing. If it becomes necessary to remove the CRT from it's mountings within the monitor, under no circumstances should leverage be applied to the CRT. Never apply pressure or leverage to the tension band. If the tension band is moved it will reduce or remove the implosion protection. NOTE: Before opening any part of the monitor, remove the power cable from the connector on the rear of the monitor. 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. Refer to the exploded view of the monitor assembly on fold out FO-3 at the rear of this chapter, and the interconnection assembly diagram shown below, while following the removal procedures. Numbers in brackets refer to the interconnecting wire numbers as shown in the diagram below

13 VIDEO AMPLIFIER VA INPUT 24V = B BLK - LEVEL = B GAIN = R BLK - LEVEL = R GAIN = G BLK - LEVEL = G GAIN VR1 VR2 VR3 VR4 VR5\ VR6 E.H.T. 22KV DEGAUSSI COIL CRT 10in. 6\ VR1 H.HOLD VR3 H.PHASE VR8 V.LIN. P2 P1 IC2 P3 DC 1 2 IC3 VR10 V.SHIFT DEGAUSSI CIRCUIT C VR2 OVERVOLTAGE PROJECTION T1.25A 250V F1 1 F1 T2.5A 250V VR7 100 LINES VR6 100 LINES VR5 350 LINES V. AMP. DEFLECTION WINDI G4 G2 G1 A PTC B 6 D VR9 V.HOLD 115V a.c. 4 A 1 5 VR12 H.WIDTH 8 VR11 E.W. KG KR KB VR13 BRIGHT 1 IEC CONNECTOR VR14 SUB BRIGHT. B RGB T2 TRANSFORMER B VR4 H.SHIFT ADAPTER RGB PREAMPLIFIER SB G2 SCAN BOARD G1 FIL 12V GND 85V 2 EHT VA VIDEO AMPLIFIER V.C. VIDEO CONNECTOR GND L2 H.LIN. VR1 12V GND V. H. BLANKI VR15 FOCUS VR16 G2 VR6 VR4 VR2 CONTRAST FOCUS G2 VR5 VR3 VR1 B R G GND INPUT SIGNAL NOTE: Assembly of the monitor is the reverse of the disassembly procedures

14 Removal of the Top Cover Unscrew the six screws located on the top of the monitor and then lift off the cover. Removal of the CRT The CRT is removed as follows: 1. Disconnect the power to the monitor. 2. Remove the top cover. 3. Discharge the anode by following the CRT discharge procedure detailed above. Remove the EHT cap from the anode of the CRT. 4. Unscrew the four screws which attach the left hand plate to the monitor. Slide the plate towards the rear of the monitor and remove it by tilting it outwards from the front of the monitor. 5. Remove the video amplifier board from the CRT base. 6. Remove the CRT ground wire (8), connected to the CRT braid, from the video amplifier board. 7. Disconnect the deflection yoke wiring harness (7) from the connector B on the scan board. 8. Disconnect the degaussing coil leads (11) from the connector B on the degaussing circuit board. 9. Unscrew the four hex nuts, one in each corner of the CRT, and gently pull the CRT forwards out of the casing. Removal of the Scan Board The scan board is removed as follows: 1. Disconnect the power to the monitor. 2. Remove the top cover. 3. Discharge the anode by following the CRT discharge procedure detailed above. Remove the EHT cap from the anode of the CRT. 4. Unscrew the four screws which attach the left hand plate to the monitor. Slide the plate towards the rear of the monitor and remove it by tilting it outwards from the front of the monitor. 5. Disconnect the following wires: The wiring harness (7) from the connector B on the scan board. The wiring harness (6) from the connector C on the scan board. The wiring harness (4) from the connector A on the scan board. 6. Remove the scan board by lifting it off the three stand-offs on the left hand plate and unscrewing the fourth stand-off which attaches the scan board to the LOPT (T2). 7. Desolder the G2 (screen grid) lead on the scan board and the G4 (focus) lead from under the insulating cover on the CRT. 8. Disconnect the wiring harness (5) from connector D and the ground lead (3) from the GND tab on the scan board

15 Removal of the Video Amplifier Board The video amplifier board is removed as follows: 1. Disconnect the power to the monitor. 2. Remove the top cover. 3. Discharge the anode by following the CRT discharge procedure detailed above. Remove the EHT cap from the anode of the CRT. 4. Unscrew the four screws which attach the left hand plate to the monitor. Slide the plate towards the rear of the monitor and remove it by tilting it outwards from the front of the monitor. 5. Remove the video amplifier board from the CRT base, and disconnect the following: The wiring harness (5) from the connector D on the scan board. The wiring harness (2) from the connector B on the RGB pre-amplifier board. The ground connection lead (3) from the GND tab on the scan board. The ground connection lead (8) from the ground tab on the video amplifier board. The focus lead (10) from the CRT socket on the video amplifier board. The G2 lead (11) from the video amplifier board. Removal of the RGB Pre-amplifier Board The RGB pre-amplifier board is removed as follows: 1. Disconnect the power to the monitor. 2. Remove the top cover. 3. Disconnect the wiring harness (4) from the connector A on the scan board. 4. Disconnect the wiring harness (2) from the connector B on the RGB preamplifier board. 5. Remove the two locking screws which hold the 15 pin D-type connector to the rear plate. Removal of the Degaussing Circuit Board The degaussing circuit board is removed as follows: 1. Disconnect the power to the monitor. 2. Remove the top cover. 3. Disconnect the degaussing coil by removing the degaussing leads from the connector B on the degaussing circuit board. 4. Disconnect the 115 Vac mains lead (9) from the connector A on the degaussing circuit board. 5. Lift the degaussing circuit board off the two stand-offs

16 ADJUSTMENTS In the event of repair and/or revision to the monitor, the adjustment procedures detailed below should be followed. NOTE: The adjustable parameters are to some extent interactive and it may be necessary to repeat sections of the procedure to obtain optimum results. The interconnection assembly diagram shown previously details all the adjustable devices and their locations on the assembly boards. The metal plates diagram below shows the locations of the controls and the connectors. SUB BRIGHT BRIGHT H.HOLD. H.LIN. H.SHIFT H.WIDTH E.W. CORRECTION V.HEIGHT SERVICE V.HOLD. H.PHASE V.PROTECT V.LIN. V.SHIFT LEFT HAND PLATE REMOVABLE SIGNAL INPUT CONTRAST + 115VAC 24V DEGAUSSI FOCUS - G2 DC SB VA SIGNAL INPUT RGB DEGAUSSI COIL 24V 115VAC - + REAR PLATE TOP VIEW WITH TOP COVER REMOVED

17 Test Equipment To carry out the adjustments, the following equipment is required: Digital multimeter to measure up to 2000 Vdc. Quantum colour character generator, model 801C. TV colour analyser. Non-inductive screwdriver for horiontal linearity adjustment. Insulated screwdriver for other adjustments. Stabilied power supply of 24 Vdc +_0.2 Vdc at 2 amps, and 115 Vac 50/60 H mains source for the automatic degaussing circuit. Degaussing coil. NOTE: For adjustments with the monitor installed in the host terminal, the character generator and the power supply/mains source will not be required. In this case, the three modes of operation are obtained by running the diagnostics tests for the monitor to produce the most appropriate test pattern. Set Up of the Character Generator The Quantum character generator is set up to obtain the following data: Mode 1 (640 x 400) Horiontal: Dots/char. = 8 Total chars. = 100 Displayed chars. = 80 Drive delay = 82 Drive width = 12 Vertical: Lines/char. = 12 Total lines/char. = 453 Displayed rows = 32 Drive delay = 34 Drive width = 9 H = kh = MH = Horiontal sync = -ve Vertical sync = +ve. Mode 2 (640 x 350) Horiontal: Dots/char. = 8 Total chars. = 100 Displayed chars. = 80 Drive delay = 81 Drive width = 12 Vertical: Lines/char. = 12 Total lines/char. =

18 Displayed rows = 28 Drive delay = 32 Drive width = 9 H = kh = MH = Horiontal sync = +ve Vertical sync = -ve. Mode 3 (640 x 480) Horiontal: Dots/char. = 8 Total chars. = 100 Displayed chars. = 80 Drive delay = 82 Drive width = 12 Vertical: Lines/char. = 12 Total lines/char. = 525 Displayed rows = 39 Drive delay = 40 Drive width = 2 H = kh = MH = Horiontal sync = -ve Vertical sync = -ve. Warm Up Horiontal Hold Apply power to the power input connector. Apply the cross hatch test pattern, mode 3, to the 15 pin D-connector. Allow the monitor to warm up for 20 minutes before making any adjustments. If the monitor is powered up from 'cold', its automatic degaussing system will demagnetie the CRT. If, however, the monitor is powered up from its 'warm' state and has been moved around, an external degaussing is required. Set the CONTRAST control to 75% of it's maximum, and the BRIGHT control so that no background raster appears. If no image is obtained, refer to the section headed "TROUBLESHOOTI INFO". 1. Short together the two test pins marked P1 and P2 on the scan board. 2. Adjust VR1 (H. HOLD) on the scan board, until the entire display drifts slowly across the screen. Vertical Hold Adjust VR9 (V. HOLD) on the scan board, so that the display gets locked when it is rolling from the top to the bottom of the screen

19 Horiontal Shift Horiontal Phase 1. Adjust VR14 (SUB. BRIGHT) on the scan board so that the background raster is visible. 2. Adjust VR4 (HOR. SHIFT) to horiontally centre the raster on the screen. If the raster is too wide, reduce its width by altering VR12 (HOR. WIDTH) on the scan board. 3. If VR14 (SUB. BRIGHT) was moved, readjust it to obtain -10 Vdc +_2 Vdc, measured between one end of VR13 (BRIGHT) on the scan board, that is jumper J23, and GND. 4. If VR12 (HOR. WIDTH) was moved, readjust it so that the horiontal sie of the display, measured along the centre of the screen, is 180 mm +_2 mm. 1. Set the brightness control (VR9, BRIGHT) to maximum so that the background raster is visible. If the background raster is not visible, adjust VR14 (SUB. BRIGHT) on the scan board until it appears. 2. Adjust VR3 (HOR. PHASE) so that the image is at the centre of the screen (see diagram below). C.R.T. Screen Geometric Distortion Zone of Uncertainty 2.5mm 4 a ) mm Centre Circle b) Centre Point mm NOTE: Total error must extend over half the horiontal and vertical amplitude. 3. If VR14 (SUB. BRIGHT) was moved, readjust it to obtain -10 Vdc +_2 Vdc, measured between one end of VR13 (BRIGHT) on the scan board, that is jumper J23, and GND. Side Pin Cushion Adjust VR11 (E.W.) on the scan board to correct any side pin cushion effects (curved or bowed edges of the display)

20 Horiontal Linearity Using a non-inductive screwdriver, adjust V2 (HOR. L. LIN) on the scan board, until the corresponding vertical columns of the cross hatch pattern are of equal width, measured along the centre of the screen. NOTE: Horiontal linearity is interactive with horiontal width, therefore both HOR. V. LIN and HOR. WIDTH may require adjustment. Horiontal Width Adjust VR12 (HOR. WIDTH) on the scan board, so that the horiontal sie of the display measured along the centre of the screen (assuming that the side pin-cushion and the geometry distortion is correctly adjusted) is 180 mm +_2 mm. Vertical Linearity Adjust VR8 (VERT. V. LIN) on the scan board, so that the horiontal rows of the cross hatch pattern, on the upper and lower halves of the screen, are of equal height. NOTE: Horiontal linearity is interactive with horiontal width, therefore both HOR. V. LIN and HOR. WIDTH may require adjustment. Vertical Amplitude (Mode 1) 1. Apply mode 1 to the monitor. 2. Adjust VR6 (VERT. AMP LINES) on the scan board, so that the vertical sie of the display, measured along the centre of the screen, is 130 mm +_2 mm. Vertical Amplitude (Mode 2) 1. Apply mode 2 to the monitor. 2. Adjust VR5 (VERT. AMP LINES) on the scan board, so that the vertical sie of the display, measured along the centre of the screen, is 130 mm +_2 mm. Vertical Amplitude (Mode 3) 1. Apply mode 3 to the monitor. 2. Adjust VR7 (VERT. AMP LINES) on the scan board, so that the vertical sie of the display, measured along the centre of the screen, is 130 mm +_2 mm. Vertical Shift Adjust VR10 (VERT. SHIFT) on the scan board, so that the display is vertically centred on the screen. Sub-brightness Adjust VR14 (SUB. BRIGHT) to obtain -10 Vdc +_2 Vdc, measured between one end of VR13 (BRIGHT) on the scan board, that is jumper J23, and GND

21 Focus 1. Apply the 'H' pattern to the monitor. 2. Set VR1 (CONTRAST) on the RGB pre-amplifier board, to 75% of it's maximum. 3. Adjust VR13 (BRIGHT) on the scan board to 75% of its maximum. 4. Adjust VR15 (FOCUS) on the scan board for the best focus over the entire screen. Cut-Off (Black Level), G2 and White Balance Adjustment 1. Set the following potentiometers on the video amplifier board fully clockwise (viewed from the top): VR1 - B. BLK. LEVEL VR2 - B. GAIN VR3 - R. BLK. LEVEL VR4 - R. GAIN VR5 - G. BLK. LEVEL VR6 - G. GAIN 2. Ensure that the sub-brightness is adjusted as described in the section headed "Vertical Amplitude (Mode 1)". 3. Set the BRIGHT control to maximum. Set the CONTRAST control (VR1 on the RGB pre-amplifier board) so that there is a signal of 28 Vp-p (black to white) at the collector of TR6 on the video amplifier board. 4. Set the screen grid (G2) potentiometer, VR16 on the scan board, to minimum. 5. Remove the test signal from the monitor by unplugging the signal cable from the D-type connector. 6. Short circuit test points P4 and P5 on the scan board. 7. Slowly adjust VR16 until one colour becomes visible. Take this colour as the reference colour for the cut-off adjustment. 8. Selecting any colour other than the reference colour, adjust the relevant black level control (VR1, VR3 or VR5), until it is as bright as the reference colour. 9. Remove the short between P4 and P Apply a full white page signal. Set the brightness control to give 60 Nits using a luminance meter. 11. Adjust the VR2, VR4 and VR6 (GAIN) on the video amplifier board to obtain the required white balance of 9300 K. 12. Readjust VR13 (BRIGHT) to give 80 Nits +_5% Overvoltage or X-Ray Radiation Protection Adjustment 1. Connect a voltmeter between test point P3 on the scan board and ground. 2. To check that the overvoltage circuit functions, set VR2 on the scan board fully anti-clockwise so that the voltage at the test point is about 5.7V. Adjust VR2 until the voltage at the test point reaches 8.0V, the monitor should switch off. Remove the 24 Vdc supply to the monitor and turn VR2 fully anti-clockwise. Apply the 24 Vdc supply. 3. Turn VR1 (CONTRAST) on the RGB pre-amplifier board to minimum so that there is no display on the screen. 4. Adjust VR2 so that the voltage at test point P3 is 6.8V +0V/-0.1V

22 TROUBLESHOOTI INFO Tools and Equipment To troubleshoot the monitor, the following tools and equipment are required: Digital multimeter to measure up to 2000 Vdc. Quantum colour character generator model 801C. Stabilied power supply of 24 Vdc +_0.2 Vdc at 2 amps, and 115 Vac 50/60 H mains source for the automatic degaussing circuit. Non-inductive screwdriver and insulated screwdriver for adjustments where required. Dual trace scope with 10:1 probes. 110/115 Vac 50/60 H mains source. NOTE: For adjustments with the monitor installed in the host terminal, the character generator and the power supply will not be required. WARNI The CRT anode retains a potentially lethal voltage even when the monitor is turned off. The EHT discharge procedure detailed in the safety section under the heading "ASSEMBLY AND DISASSEMBLY" must ALWAYS be observed prior to disconnection of the EHT cap or any other task which requires the CRT to be handled. The following flowchart is a guide to troubleshooting the monitor

23 No Raster Check +24V Measured on pin 1 of connector C on the scan board. Check 24V voltage source in the terminal Adjust VR2 on scan board completely anti-clockwise to inhibit the overvoltage protection circuit. Turn the 24V supply off and then on. Adjust VR2 as detailed in the overvoltage protection adjustment procedure Measure EHT voltage and waveform at collector of TR5 on scan board Check flyback voltage waveform of 500 Vp-p at pin 10 of T2 Check F1, D19 open, C21 Check 12V at pin 2 of IC4 Check: H. oscillator H. deflection High voltage circuit IC4 Check booster voltage atpin5oft2 C22 Check CRT heater Heater lit Heater not lit R21 on video amplifier. Heater lead from scan board to video amplifier. CRT. Adjust BRIGHT and SUB.BRIGHT Check screen grid voltage G2 = 300V to 750V Too low BRIGHT and SUB.BRIGHT not adjusted CRT. G2 lead to video amplifier. R22, C5 on video amplifier. LOPT T2 failure. Check 12V supply to RGB pre-amplifier and video amplifier. Check ener voltage = 5V1 at D2 on video amplifier. Check B+ on the video amplifier =85Vdc Too low R34, D27, C31, LOPT T2 pin 8 on scan board. D1, C4 on video amplifier CRT failure

24 No Picture - Raster Check RGB input at J9, J8 and R30 on the RGB pre - amplifier = 0.7 Vp - p - Check connection between terminal and monitor Check RGB output at connector B pins 2, 3, 1 on RGB pre -amplifier Check no flyback at C30 on video amplifier. TR7 failed. Check RGB output at collectors of TR1, TR3 and TR5 on video amplifier Check D1, C3, C4 on video amplifier. No 85V B+. CRT cathode failure

25 Low or Loss of R, G or B Check RGB input at J9, J8 and R30 on the RGB pre-amplifier = 0.7 Vp-p Check connection between terminal and Monitor Check RGB output at pin 6 of IC1, IC3 or IC2 on RGB pre-amplifier or low Check TR1, TR5 or TR3 Check IC1, IC3 or IC2. Check D1, D5 or D3. Check RGB output at connector B pin 2, 3 or 1 on, RGB pre-amplifier or low Check D2 / TR2, D6 / TR6 or D4 / TR4 Check RGB output at collector of TR1, TR3 or TR6 on video amplifier CRT cathode failure Check TR2 / TR1, TR4 / TR3 or TR6 / TR5. If low Check white balance

26 Abnormal Video on CRT - Too Bright or Too Dark Check video input Check video output Measured at connector B on RGB pre-amplifier Check RGB output at collectors of TR1, TR3 and TR5 on video amplifier Check B+ = 85 Vdc on video amplifier Low or 0V TR7 faulty, +12V on RGB pre-amplifier Check video bias at D2, +12V on video amplifier R34, D27, C31, on scan board. D1, C3, C4 on video amplifier Check brightness circuit on G1 and - 140V lines - Adjust BRIGHT and SUB. BRIGHT controls R33, D26, C30, D18, TR6 on scan board Check screen voltage VG2 Too low CRT, C5, T2 LOPT 300 to 700V CRT failure

27 No Blanking - Visible Retrace Line on the Back Raster Check blanking circuit Check H.flyback and V.flyback at R22 and R20 on scan board. If no H.flyback T2 LOPT If no V.flyback IC3 Check H and V blanking at collector of TR6 on video amplifier Check D14, D15, TR6 and D18. No 85V. Bad Horiontal and Vertical Synchroniation Horiontal Adjust HOR.HOLD VR1 on scan board Check H.sync. input, pin 12 of IC1 on scan board Check H.sync. at collector of TR3 on scan board Check synchroniation input circuit Check connection between terminal and monitor. Check R2, D3, D1 on scan board IC1, TR3, D2 on scan board. Check +5V on pin 14 of IC1. IC2, C10, C

28 Vertical Adjust V. HOLD, VR9 on scan board Check V. sync input pin 1 of IC1 on scan board Check V. sync. at pin 5 of IC3 Check connection between terminal and monitor. Check R3, D5 and D4 on scan board Check vertical oscillator circuit IC3, C39, D8 Abnormal Vertical Height in 480 Line Mode Check 24 Vdc line Measured after R51 on scan board Low R51, C36, R43 on scan board Check vertical mode circuit by adjusting VR4, VR5, or removing TR1, TR2 Failure of TR1 or TR2 or see Vertical Mode section, below Check vertical deflection circuit Failure of IC3, vertical deflection coil, C34, R65, D7. Readjust VR7 ( VERT. AMP 480 LINES ) on scan board

29 Vertical Mode Vertical Mode Failure condition: - Too small Vertical Height at 400 lines and 350 lines Vibrating Vertical Height - Check IC1, TR1, TR2, D2 on scan board Readjust VR5 ( VERT. AMP. 350 LINES ) and VR6 ( VERT.AMP. 400 LINES ) Side-Pin Cushion Distortion Failure Readjust E.W., VR11 on scan board No field parabola at base of TR8 on scan board Failure of: D22, TR8, C43, C44, TR9, R84, C46, TR10 Poor Focus Readjust FOCUS control, VR15 on scan board. Failure of focus control circuit, focus lead, CRT socket or CRT

30 CONNECTOR ASSIGNMENT Video and Sync Connector Video and sync data is input to the top of the monitor through a 15 pin D-type connector with the following pinout: +24 Vdc Power Input Connector +24 Vdc and its return (GND) is input to a two pin Molex connector on the top of the monitor. The pinout is as follows: V RTN +24V 115 Vac Power Input Connector 115 Vac is input to a three pin IEC 320 connector on the top of the monitor. The pinout is as follows: L N E LIVE NEUTRAL EARTH

31 SCHEMATIC DIAGRAMS 56/588X TEN INCH VGA COLOUR MONITOR (Y0F9151) Fold-out sheet FO-1 details the schematic diagram for the monitor and foldout sheet FO-2 details the schematic diagram for the RGB Pre-amplifier. Foldout sheet FO-3 details the exploded view of the monitor assembly

32