Service Manual for Wells-Gardner 19”
Contents
1. DVAGEI 8s vel VOZ NIT sou 99 FIG 14 Desig nator C1 C3 C4 C6 C7 C9 C10 C1 GIZ C13 C14 C 5 C16 C17 C18 C19 C20 C2 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36 A C37 C38 C40 C41 Parts Lists This monitor contains circuits and components included specifically for safety pur poses The two symbols described below are used in the parts lists to mark com ponents that you should replace only with exact factory replacement parts Using substitute parts may create a shock fire radiation or other hazard Only qualified personnel should perform service indicates parts that influence X ray radiation in the horizontal deflection and high voltage circuits the picture tube etc A indicates safety critical parts P447 Main Board Parts List Description Capacitors Capacitor ceramic 22 pF 1096 npo Capacitor electrolytic 10 pF 25 V np Capacitor mylar O22 pF 10 50 V Capacitor electrolytic 33 uF 16 V Capacitor electrolytic 22 pF 25 V Capacitor electrolytic 1 0 LF 50 V Capacitor electrolytic 22 pF 25 V Capacitor mylar 022 pF 10 50 V Capacitor mylar 1 uF 10 50 V Capacitor polyester O1 pF 10 50 V Capacitor electrolytic 1 0 pF 50 V Capacitor pp 0056 pF 2 AWS 500 V Capacitor electrolytic 10 pF 25 V Capacitor electrolytic 1 0 pF 50 V Capacitor electrolytic 47 pF 25 V Capacitor mylar 02. 590 Ya W Resistor 3 3K Q 5 Ya W Resistor 1 2K Q 5 Ya W Resistor 56K Q 590 Ya W Resistor 180K Q 59 0 Va W Resistor 12K Q 5270 Ya W Resistor 220K Q 590 V4 W Resistor 62K Q 5 Va W Resistor carbon 22K Q 5900 Ya W Resistor 68K Q 590 1 2 W Resistor 6 8K Q 59 60 V4 W Resistor 47K Q 59 0 V2W Atari Part No 99 130984 99 130985 99 130986 99 130869 99 130586 99 130369 99 130355 99 130392 99 130870 99 130581 99 130392 99 130871 99 130869 99 130685 99 130643 99 130870 99 130783 99 130572 99 130581 99 130351 99 130392 99 130658 99 130870 99 130658 99 130392 99 130657 995130373 99 130377 99 130351 99 130392 99 130581 99 130392 99 130355 99 130685 99 130351 99 130586 99 130384 99 130578 99 130581 99 130871 99 1905 2 99 130658 99 130871 99 130873 99 130578 99 130685 99 130872 99 130783 99 130677 99 1390395 99 130875 Desig nator R72 R73 R74 R75 R76 R77 R78 R80 R81 R82 R83 R84 R85 R86 R87 R88 R89 R90 R92 R93 R94 R95 R96 R97 R98 R99 R100 R101 R102 R103 R104 R105 R106 R107 R110 R111 R301 Ti T2 VR1 VR2 VR3 VR4 VRS VR6 VR7 VR8 VRQ F1 P447 Main Board Parts List Continued Description Resistor 100 Q 59 6 1 4 W Resistor 10K Q 595 Ya W Resistor 22 Q 5 Ya W Resistor 2 2K Q 525 1 4 W Resistor 47K Q 520
3. P456 P P6 J6 P20i 447 JS cuo p R30 100 M Cu 22 25V 4 4 11I5 R32 R2 100 sex R22 56K R23 IK CONTRAST R33 2501398 XA 6100 I500v RI4 22 C35 9 HORIZONTAL OUTPUT CUTOFF DRIVE CUTOFF DRIVE CUTOFF DRIVE mum ss R98 R99 2 2K IW 2 2K IW 200 v w a YO RED N BLU R207 R208 R209 e cT XA D CN m kn DS n 7 MEE FER GR Va E TT P202 L 3 5 s ALTERNATE CRT AND NECK J202 gt al ES NOTES ALL RESISTORS ARE IN OHMS I 4W SY UN LESS OTHERWISE INDICATED 2 CAPACITANCE VALUES LESS THAN ARE IN MICROFARADS ABOVE I IN PICOFARADS UN LESS OTHERWISE INDICATED CIRCLED NUMBERS INDICATE LOCATIONS OF CERTAIN WAVEFORM READINGS A CAUTION SAFETY CRITICAL COMPONENT aum EREMO GREE CE AS Ge Ca DIG c38 39 R97 L amp 270 3W ous RADIATION RELATED COMPONENT REPLACE ONLY WITH SAME TYPE HOR o POS ie CR En PARTS AS SHOWN IN PARTS LIST ADJUST 017 VERTICAL Md POSITION UM a Gum q 9K7 700 SERIES ya ISK7800 SERIES ISK 7600 SERIES DEFLECTION I9K7900 SERIES NOTE REFER TO OTHER SCHEMATIC DIAGRAMS FOR CERTAIN UNIQUE MOOELS 13
4. Va W Resistor 33K Q 520 V4 W Resistor 1K Q 5290 1 4 W Resistor 5 6 Q 596 2 W Resistor 150 500 ka W Resistor 8202 505 V2 W Resistor 680 Q 595 V2 W Resistor 6 8K Q 520 Ya W Resistor 3 3K Q 520 Ya W Resistor 220K Q 520 Ya W Resistor 330K Q 1096 V2 W Resistor 1 8K Q 500 1 W Resistor mo 3 9K Q 596 5 W Resistor mf 1 22 599 2 W Resistor 1K Q 5 2 W Resistor 47K Q 522 1 4 W Resistor ww 1 8K Q 520 3 W Resistor 2702 5 3 W Resistor mo 2 2K Q 5 1 W Resistor 270 Q 4590 1 W Resistor 6 8K Q 4596 3 W Hesistor 47 Q 5 1 W Resistor 2 7 Q 5 7 W Resistor 150 5 5 W Thermistor Resistor 27K Q 50 Ya W Resistor 1K Q 59 0 V4 W Resistor 27K Q 590 Va W Resistor 4 7K Q 500 1 4 W Resistor ww 220 Q 15W Transformers Transformer flyback Transformer horiz driver Potentiometers Potentiometer 500 Q Potentiometer 10K Q Potentiometer 200 N Potentiometer 200K Q Potentiometer 2K Q Potentiometer 10K Q Potentiometer 2K Q 3 W Potentiometer 200 Q Miscellaneous Fuse 1 5 Amp Slow Blow Final Assembly Parts Purity Convergence Ring Assembly Cathode Ray Tube Philips Type MVA48AB05X 52 Deflection Yoke Atari Part No 99 130351 99 130581 99 130867 99 130373 99 130657 99 130369 99 130392 99 130874 99 130592 99 130868 99 130598 99 130395 99 130572 99 130685 99 130876 99 13084
5. AND SET UP PROCEDURE DEGAUSSING Demagnetize the shadow mask and all surrounding metal parts with an external degaussing coil PURIT Y Adjust the purity magnets and the yoke position STATIC CONVERGENCE Converge Red and Blue on Green in the center of the screen DYNAMIC CONVERGENCE Converge Red and Blue at the edges of the screen WHITE BALANCE Set Gray and White brightness tracking NOTE Purity and convergence adjustment interact DEGAUSSING The monitor is equipped with an automatic degaussing circuit How ever if the CRT shadow mask has become excessively magnetized it may be necessary to degauss it with a manual coil Do not switch the coil OFF while the raster shows any effect from the coil COLOR PURITY ADJUSTMENT 1 For best results it is recommended that the purity adjustment be made in the final monitor location If the monitor will be moved per form this adjustment with it facing west or east The monitor must have been operating 15 minutes prior to this procedure 2 On picture tubes with a 22 5 mm neck diameter set the ring as sembly on the CRT neck with the center line of the purity ring pair over the gap between grids No 5 and 6 See Fig 2A For picture tubes with a 29 mm neck use the gap between grids No 3 and 4 Fig 2B 3 Make certain that the magnetic ring pairs are in their correct start ing positions before beginning this procedure The correct starting position for the purity ring pair is not
6. V Capacitor ceramic 100 pF 10 Z5F 500V Capacitor electrolytic 100 pF 35 V Capacitor polyester 01 pF 10 50 V Capacitor electrolytic 1000 pF 25 V Capacitor tantalum 63 pF 10 35 V Capacitor polyester 01 nF 10 50 V Capacitor polyester 033 pF 5 50 V Capacitor mylar O22 pF 5 50 V Capacitor electrolytic 560 pF 200 V Capacitor electrolytic 22 pF 160 V Capacitor electrolytic 47 pF 160 V Capacitor ceramic 0015 pF 10 Y5P 500V Capacitor ceramic 0022 pF 10 Y5P 500V Capacitor 1 uF 20 125 VAC Capacitor polyester O1 uF 10 50 V Semiconductors D ode 1N914B Diode zener 5 1 V 5 Vo W Diode zener 10 V 5 1 2 W Diode switching Diode Sanyo GFE10R Diode 1 A 600 V Diode boost Integrated Circuits IC video UPC 1397 IC horiz vert LA7823 IC vert output UPC 1378 IC regulator STRZ123 Insulator mica Coils Coil width TODAI Coil linearity TODAI Atari Part No 99 130963 99 130955 99 130964 99 130965 99 130956 99 130966 99 130947 99 130967 99 130968 99 130947 99 130969 99 130970 99 130971 99 130972 99 130973 99 130974 99 130975 99 130976 99 130947 99 130977 99 130978 99 130979 99 130980 99 130981 99 130982 99 130983 99 130987 99 130988 99 130989 99 130991 99 130990 99 130992 99 130993 Desig nator Q1 Q9 Q10 Q11 R1 R3 R4 R6 R7 R9 R10 Ri2 R13 R 5 Ri6 R 7 R1
7. in verted by Q5 and Q6 then applied through D3 D4 and R51 to the sync amplifier Q7 The sync amplifier output is applied through C22 R53 and R55 to pin 14 of IC2 Pin 14 is the sync separation input The sync separator extracts the horizontal and vertical sync from each other providing horizontal sync to the hori zontal AFC circuit in the IC A composite sync output is pro vided at pin 12 This output signal is used for gating IC1 the video interface IC and for triggering the vertical oscillator HORIZONTAL OSCILLATOR AND OUTPUT The horizontal AFC circuit of IC2 receives a horizontal sync input from the sync separator and a feedback signal at pin 1 derived from the horizontal output Slight differences in frequency and phase of the two signals will cause the AFC to generate a correction voltage at pin 2 The horizontal oscillator inIC2 has its free running frequency determined by the RC time constant of C19 R56 R57 R58 and VR2 the horizontal hold control The horizontal hold control varies the horizontal frequency by varying the RC time constant Slight correction in frequency is provided by a correction voltage at IC2 pin 3 which comes from pin 2 through R60 The oscillator output at pin 4 is amplified and shaped by the horizontal drive stage Q10 The drive signal is then coupled to the base circuit of the horizontal output transistor Q11 by the horizontal drive transformer T2 T2is used for impedance transformation to pr
8. tube in all models Therefore wherever vertical appears in this manual or on the monitor it refers to the short dimension of the picture tube wherever horizontal appears it refers to the long dimension of the picture tube TROUBLESHOOTING CHART NO PICTURE SEE NOTE 4 CRT FILAMENT LIT CHECK FOR GATE PULSE AT ICI PIN 12 CHECK FILAMENT CIRCUIT CHECK ALONG VIDEO CHANNEL FROM VIDEO INPUT AT PI TO VIDEO OUTPUT TRANSISTORS ON NECK BOARD CHECK FOR GATE PULSE OUTPUT FROM 1C2 PIN 12 REFER TO NO HIGH VOLTAGE CHART CHECK FOR OPEN HORIZONTAL YOKE CIRCUIT REFER TO SYNC PROBLEMS CHART SYNC PROBLEMS SEE NOTE 8 NO HOR SYNC NO VERT SYNC NO HOR SYNC VERT SYNC OK NO VERT SYNC HOR SYNC OK CHECK SYNC AMPL CKT Q7 CHECK HOR SYNC INVERTER CKT Q6 CHECK IC2 CHECK HOR AFC IC2 PINS 2 AND 3 CHECK IC 2 CHECK IC 2 CHECK VERTICAL OSCIL LATOR AND TRIGGER CKTS IC2 PINS 10 11 12 AND 13 NO HIGH VOLTAGE CHECK B 123V AT IC4 PIN4 NECK BOARD P202 PIN 3 B GREATER THAN 130 VDC NO CHECK AC B INPUT LOOK FOR CAUSE OF SHORTED IC4 OVERLOAD CONDITION SHORTED Q 11 FOR EXAMPLE CHECK FOR SHORTED C4 B4 REGULATOR IC4 PINS 1 4 SHORTED IC4 OK CHECK FUSE IF FUSE IS OPEN CHECK FOR SHORTED HOR OUT PUT TRANSISTOR QII AND SHORTED B REGULATOR
9. 0 99 130926 99 130927 99 130841 99 130657 99 130928 99 130842 99 130687 99 130839 99 130843 99 130838 99 130829 99 130830 99 130931 99 130643 99 130392 99 130643 99 130586 99 130932 99 130994 99 190995 99 130933 99 130934 99 130935 99 130936 99 130937 99 130934 99 130938 99 190939 99 130996 99 131002 99 130815 99 130818 Designator C201 C203 C204 C205 Q201 Q203 R201 R202 R203 R204 R207 R209 H210 R212 H213 VR201 VR202 VR203 VR204 VR205 VH206 SKT201 P456 Neck Board Description Capacitors Capacitor ceramic 470 pF 1020 Z5F Capacitor ceramic 01 uF 10 YSP 500 V Capacitor ceramic 0015 zF 1 5 KV Transistor Transistor 2SC2068LB LBBK Resistors Resistor 2 7K Q 5 Va W Resistor 1502 5 Ya W Resistor 2 7K Q 5 Va W Resistor 1502 590 Ya W Resistor 2 7K Q 59 0 Va W Resistor 150 Q 5270 Va W Resistor metal oxide 6 8K Q 59 9 2 W Resistor 2 7K Q 1096 1 2 W Resistor 68 Q 590 2 W Potentiometers Potentiometer 2 0K Q Poteniometer 200 Q Potentiometer 2 0K Q Potentiometer 200 Q Potentiometer 2 0K Q Potentiometer 200 Q Miscellaneous CRT Socket 49 Part No 99 130998 99 130958 99 130999 99 131000 99 130738 99 130355 99 130738 99 130355 99 130738 99 130355 99 130802 99 130583 99 130997 99 130937 99 130935 99 130937 99 130935 99 130937 99 130935 99 131
10. 0 Pixels x 240 Lines 25 560 Pixels x 240 Lines e Fine Pitch CRT 410 Pixels x 240 Lines 640 Pixels x 240 Lines 640 Pixels x 240 Lines N A SPECIFICATIONS ARE SUBJECT TO CHANGE IN ORDER TO ASSURE YOU THE LATEST IN DISPLAY TECHNOLOGY Copyright 1987 Wells Gardner Electronics Corporation All rights reserved wells Gardner ELECTRONICS 1 N KILDARE CHICAGO IL 60639 CORPORATION 312 2528220 TELEX 25 3286 FAX 312 252 8072 SERVING CONSUMER ANO INDUSTRIAL ELECTRONICS FOR MORE THAN 60 YEARS THIS MANUAL APPLIES TO THOSE MONITORS WITH SERIAL NUMBERS OF 576001 AND ABOVE WARNINGS 1 Power Up Warning An isolation transformer must be used between the AC supply and the AC plug of the monitor before servicing testing or operating the monitor since the chassis and the heat sink are directly connected to one side of the AC line which could present a shock hazard Before servicing is performed read all the precautions labelled on the CRT and chassis 2 X RAY RADIATION WARNING NOTICE WARNING PARTS WHICH INFLUENCE X RAY RADIATION IN HORIZONTAL DEFLECTION HIGH VOLTAGE CIRCUITS AND PICTURE TUBE ETC ARE INDICATED BY w IN THE PARTS LIST FOR REPLACEMENT PURPOSES USE ONLY THE TYPE SHOWN IN THE PARTS LIST 3 High Voltage This monitor contains HIGH VOLTAGES derived from power supplies capable of delivering LETHAL quantities of energy Do not attempt to service until all precautions necessary for working on HIGH VOLT
11. 015 E TT A OR LAT c bato an pew yon Th inerte uen a de i mn n ERA ne MA e Lido e aye Ak PX ete an e a SE Wem nC iur povera K7000 COLOR MONITOR SCHEMATIC DIAGRAM Q 2N3904 Na Q2 R2 2N3904 RI4 C3 22 SA V Ta Q3 RIS 2N3904 K ICI UPCI397C 22 21 20 19 18 wD ow c RE 2N3904 DIO oi R37 GRN 2 Qs 8 2K 1 HUT DOWN BLU 3 Fin A 012 10V GND 4 6 622 RAO Rss vre C20 C21 a x IOO D3 R60 C19 R62 OR SYNC 6 R49 3 3K K AT Rai SR45 56 5600 PP 1 2K K 100K os En VERT SYNC 2C he D4 IOK or E c18 RE HOR SYNC 3 02 2N3904 1 50v 1 8K R47 P R42 an I LA7823 16 15 14 FI LSASB Ha ZOVACI C64 SC 60Hz 125 V AC J3 R84 R85 Eoy 6 8K 3 3K D24 RIO2 R86 47 1W 220K sop th gs 200V I60V DEGAUSSING COIL 2 3 4 5 6 7 8 9 I7 16 15 14 13 8 I312 11 10 9 VRT IOK R24 IO 11 27K 09 R27 12 R68 R69 08 ses Se 22k 68k 2W 1 2K cm R39 C29 R7O R I Or 12K Ol 6 8K 47K 2W c30 C3i Ol OO HOR olo f25c2 482 R77 C49 33K Ol RTICAL Q9 299 Ch IOK R80 5 6 RIOO 1 2W 270 1W R302 IS PRESENT ONLY ON I9K 7600 AND 9K 7900 SE RIES MONITORS 19 50 60Hz ALTERNATE CIRCUIT FOR te LATER PRODUCTION VERTICAL SIZE QI VRi HORIZONTAL 500 POSITION T2 a C36 uu
12. 68 F 10 50 V Capacitor polyester 015 F 10 50 V Capacitor mylar 1 uF 10 50 V Capacitor ceramic 220 pF 10 Z5F Capacitor 5 pF 20 2 KV npo Capacitor polyester 01 pF 10 50 V Capacitor ceramic 001 pF 20 Z5F 500V Capacitor polyester 010 pF 10 50V Capacitor ceramic 100 uF 10 Z5F 500V Capacitor ceramic 0033 pF 10 Y5P 500V Capacitor ceramic 01 pF 10 Y5P 500V Capactor polyester 01 uF 10 50V Capacitor pp 6100 pF 2 1 5 KV Capacitor pp 15 uF 100 V Capacitor pp 39 uF 590 200 V Capacitor electrolytic 2200 pF 35 V Capacitor ceramic 001 pF 20 Z5F 500V Atari Part No 99 130940 99 130941 99 130942 99 130943 99 130944 99 130945 99 130944 99 130942 99 130946 99 130947 99 130945 99 130948 99 130949 99 130945 99 130950 99130951 99 130952 99 130946 99 130953 99 130954 99 130947 99 130955 99 130947 99 130956 99 130957 99 130958 99 130947 99 130959 99 130960 99 130961 99 130962 99 130955 Desig nator C42 C43 C44 C45 C46 C47 C48 C49 C50 C51 C52 C53 C54 C55 C56 C57 C59 C60 C61 C62 C63 D1 D10 D11 D12 D13 D17 D18 D19 D24 D25 IC1 IC2 IC3 IC4 IC4 Li L2 Description Capacitor electrolytic 1000 pF 16 V Capacitor ceramic 001 pF 2096 Z5F 500V Capacitor pp 1 pF 10 100 V Capacitor electrolytic 470 pF 16
13. 9 R20 R21 R22 R24 R25 R26 R27 R28 R29 R30 R32 R33 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R52 R53 R54 R55 R56 R57 R58 R59 R60 R61 R62 R63 R64 R65 R66 R67 R68 R69 R70 R71 Description Transistors Transistor NPN 2N3904 Transistor NPN cc Transistor 25D1398 Resistors Resistor 5 6K Q 5 Ya W Resistor 4 7K Q 5 Ya W Resistor 33K 2 5 V4 W Resisior 1500 5 va W Resistor IK Q 59 0 Ya W Resistor 8 2K Q 506 V4 W Resistor 10K Q 595 Ya W Resistor 1K Q 590 1 4 W Resistor 56K 2 590 Ya W Resistor 5 6K Q 5 1 4 W Resistor 220K Q 590 Va W Resistor 27K Q 596 Ya W Resistor 8 2K Q 500 Ya W Resistor carbon 22K Q 520 Ya W Resistor 3 3K Q 5 Ya W Resistor 10K Q 590 Va W Resistor 1000 5 V4 W Resistor 1KQ 5 Va W Resistor 1 2K Q 590 1 4 W Resistor 8 2K Q 59 6 Ya W Resistor 1 2K Q 590 Va W Resistor 1K Q 590 Va W Resistor 47K Q 590 Ya W Resistor 2 2K Q 5 Va W Resistor 100K Q 59 0 Ya W Resistor 100 Q 59 6 Ya W Resistor 1K Q 5970 4 W Resistor 10K Q 5 Ya W Resistor 1K Q 59 0 Va W Resistor 150 Q 590 Va W Resistor 220K Q 5 14 W Resistor 1000 5970 V4 W Resistor 4 7K Q 5960 Ya W Resistor 1 8K Q 59 0 V4 W Resistor 12K Q 52 0 V4 W Resistor 10K Q 5 Va W Resistor 56K Q
14. AGE equipment have been observed 4 CRT Handling Care must be taken not to bump or scratch the picture tube as this may cause the picture tube to implode resulting in personal injury Shatter proof goggles must be worn when handling the CRT High voltage must be completely discharged before handling Do not handle the CRT by the neck 5 PRODUCT SAFETY NOTICE WARNING FOR CONTINUED SAFETY REPLACE SAFETY CRITICAL COMPONENTS ONLY WITH MANUFACTURER RECOM MENDED PARTS THESE PARTS ARE IDENTIFIED BY SHADING AND BY A ON THE SCHEMATIC DIAGRAM AVERTISSEMENT POUR MAINTENIR LE DEGRE DE SECURITE DE L APPAREIL NE REMPLACER LES COMPOSANTS DONT LE FONCTIONNEMENT EST CRITIQUE POUR LA SECURITE QUE PAR DES PIECES RECOMMANDEES PAR LE FABRICANT For replacement purposes use the same type or specified type of wire and cable assuring the positioning of the wires is followed especially for H V and power supply circuits Use of alternative wiring or positioning could result in damage to the monitor or in a shock or fire hazard AC CONNECTORS AND TERMINALS ALL MONITORS EXCEPT THOSE WITH MODEL NUMBERS ENDING WITH 2 OR 6 WELLS GARDNER END W G Part No Molex Part No Plug 6A0396 001 19 09 2029 Pins Male 30X0759 001 02 09 2101 USERS END Receptacle 19 09 1029 Pins Female 02 09 1101 or 02 09 1116 MODEL NUMBERS ENDING WITH 2 WELLS GARDNER END W G Part No Molex Part No Plug 6A0376 002 03 09 2022 Pins Male 30X0759 001 02 09 2101 USERS E
15. C feedback at C2 pin 9 maintains good vertical linearity at all sizes DC current from the 24V supply flows through R83 and through the yoke to provide downward raster shift Some of this DC current is diverted from the yoke through the col lector of Q9 The amount of this current which is diverted from the yoke can be varied by varying the base drive to Q9 by adjusting VRB the vertical position control thus provid ing manual adjustment of the vertical position of the display The drive signal at IC3 pin 2 is also used to furnish the vertical blanking input to IC1 pin 13 via R63 and C14 AUTOMATIC DEGAUSSING ADG The ADG circuit automatically demagnetizes the CRT This circuit is activated only when the monitor is initially powered up after having been off for at least 20 minutes R105 is a positive temperature coefficient device When it is cold it has a very low resistance As it gets warm its resistance increases If the monitor is cold when AC power is applied then R105 with a low resistance allows current to pass through it D23 D24 and the degaussing coii As current flows through R105 it heats up and eventually has a very high resistance allowing very little current to flow through it The residual current now flowing through R105 produces a voltage drop across R104 of less than O 6 volts This is not enough to forward bias D23 and D24 so there is no current through the degaussing coll The process of initially havin
16. DIV 1V DIV O 2MSEC DIV 1V DIV 0 2MSEC DIV 1V DIV 0 2MSEC DIV 2V DIV O 2MSEC DIV 1V DIV O0 2MSEC DIV auaa mn m m nee er SUCEDE IQSEMENNEBMMNMM E EE IM 1 VW EMEN m Fe VIN we ANLE TROUBLESHOOTING NOTES The troubleshooting chart mentions specific components to be checked It is intended that the entire circuit associated with these components be checked This chart is a guide to servicing rather than a complete list of each component that could fail Therefore troubleshooting should not be limited only to those components mentioned in the chart It is always useful to begin checking a circuit by measuring the DC voltages and then comparing the measurements to those listed in the Typical DC Voltages chart The cutoff controls and drive controls on the neck board and the screen control at the bottom of the flyback transformer have been preset at the factory When servicing the monitor for a lack of video do not adjust any of these controls unless it is suspected that the problem is a result of these controls having been tampered with Otherwise do not adjust these controls if they are so severely out of adjustment that there is a lack of video then there is something malfunctioning The Wells Gardner Service Department does accept telephone calls for servicing assistance Call 1 312 252 8220 between 7 00am and 3 30pm Central Time Ask for the Service Department The Service Department is clo
17. Erden k TM 296 o NA 1st printing Service Manual for Wells Gardner 19 Standard Resolution 52 Video Display Model 19K7901 IN ATARI GAMES Published by Atari Games Corporation e P O Box 361110 Milpitas CA 95035 e 408 434 3950 Telex 5101007850 THE PRISMATIC WELLS GARDNER COLOR SPECIFICATIONS CRT e From 9 to 25 diagonal measure e P22 phosphor e Polished faceplate standard variety of optional faceplates and transmittances available e Stripe trio spacings standard 0 62 mm 9 0 66 mm 13 0 82 mm 19 0 82 mm 25 e Optional finer pitches available INPUT SIGNALS e Video RGB analog 1v to 5v peak to peak adjustable with contrast control 4 7k ohm input impedance 40 usec to 50 usec active video Optional inputs available Negative video RGB analog 0 0 75v 75 ohm input impedance Composite video NTSC Both composite video and RGB analog Both signal sources can be connected to the monitor at the same me Monitor display can be switched from one to he other at anytime at pixel or vertical frame rate e Sync TTL positive or negative going separate or com posite Input impedance 20K ohms for positive going sync 12K ohms for negative going sync HORIZONTAL SCAN e Width Adjustable with just one coil to accommodate active video from 40 usec to 50 usec e Frequency 15 1 kHz to 16 8 kHz standard higher scan frequencies avali
18. IC4 USING VARIAC DECREASE AC INPUT TO ZERO THEN SLOWLY INCREASE AC SUCH THAT B 123 VDC MONITOR STILL DOES NOT OPERATE MONITOR OPERATES CHECK WHETHER HOR OS CILLATOR IS OPERATING CHECK WAVEFORM 8 AND IC 2 PINS 1 2 3 4 AND 16 CHECK RETRACE TUNING CAPACI TOR C36 H V HOLD DOWN CIRCUIT IS PREVENTING MONI TOR OPERATION AT NORMAL AC INPUT CHECK FOR FAULTY CONDITION CAUSING H V TO BE TOO HIGH EXAMPLE C36 DECREASED IN VALUE CHECK H V HOLD DOWN CIRCUIT D10 D12 IC2 VERTICAL SWEEP PROBLEMS SEE NOTE 8 BRIGHT THIN CHECK NO OR VERY WAVY LINE AT LITTLE VERTI 24V VAR CENTER OF CRT CAL SWEEP SUPPLY CHECK FOR OPEN VERTI CHECK CAL YOKE WINDINGS OR IC 3 VERTICAL YOKE PATH CHECK VERTICAL DRIVE AND FEED BACK CKTS IC2 PINS 7 8 9 10 amp 11 DC BLOCKING CHECK VERTICAL POSITION CKT Q9 CAPACITOR C50 VIDEO INTERFACE AND OUTPUT The red green and blue video inputs come into the monitor P1 Isolation and attenuation is provided by emitter followers 1 Q2 and Q3 Forced blanking of the video signals is pro vided by the circuit of Q4 D5 D6 and D7 The forced blank ing causes there to be an interruption in the video signal before it goes to the inputs of IC1 This interruption occurs between scan periods while retrace is taking place it is re quired by IC1 The forced blanking is not necessa
19. L SIZE CONTROL This control must be adjusted slowly if necessary until the picture or test pattern attains the correct vertical proportions VERTICAL RASTER POSITION CONTROL VR3 If the video is off center vertically short dimension of pic ture tube some compensation can be made by turning the vertical raster position control CUT OFF AND DRIVE CONTROLS ON NECK BOARD VR201 VR202 VR203 VR204 VR205 VR206 These controls have been preset at the proper gray scale Before adjusting any of these controls refer to Trouble shooting Note 4 and to the White Balance procedure GREEN ORIVE HORIZ SIZE GREEN CUT OFF E BLU CUT OFF HORIZ RASTER POSITION HORIZ VIDEO SHIFT HORIZ HOLO x VERT RASTER POS E JE 2 VERT SIZE iu E VERT HOLD BRIGHTNESS O H SYNC NO V SYNC GND L CONTRAST FIG 1A BLUE BLUE DRIVE CUT OFF GRN DRIVE GREEN CUT OFF RED DRIVE W i HORIZ RASTER POSITION FUSE TP5 TP4 RED CUT OFF SCREEN HORIZ VIDEO SHIFT HORIZ MOLD VERT RASTER POS VERT SIZE VERT HOLD BRIGHTNESS FIG 1B INSTALLATION AND SERVICE INSTRUCTIONS NOTE All of the following procedures have been performed at the factory and should require no further attention If the monitor is serviced for ny reason it should be observed afterward to determine whe ier any Jf these procedures need to be performed again OUTLINE OF CONVERGENCE
20. ND Receptacle 03 09 1022 Pins Female 02 09 1101 or 02 09 1116 MODELS NUMBERS ENDING WITH 6 WELLS GARDNER END W G Part No AMP Part No Receptacle 6A0402 001 350778 1 Pins Male 30X0761 001 350538 1 USERS END Plug 350777 1 Pins Female 350537 1 or 350851 1 1101 is used for 20 14 AWS wire and insulation diameter range 0 065 0 160 1116 is used for 22 18 AWG wire and insulation diameter range 0 060 O 120 350537 1 is used for 20 14 AWG wire and insulation diameter range O 130 0 200 350851 1 is used for 24 18 AWG wire and insulation diameter range 0 040 0 100 10 11 12 USER ADJUSTMENTS BRIGHTNESS CONTROL VR6 This control has been preset at the factory However when the video signal is applied to the monitor a slight adjust ment may be desired Adjust this control such that the il lumination is just barely extinguished from portions of the display which should be black CONTRAST CONTROL VR7 Adjust the contrast control forthe desired picture intensity FOCUS CONTROL Adjust the focus control located on the high voltage unit T1 for maximum over all definition and fine picture detail HORIZONTAL HOLD CONTROL VR2 With the monitor being driven with the display signal con nect one jumper between TP1 and TP2 and another jumper between TP3 and TP4 Adjust the horizontal hold control unti the picture stops sliding horizontally Remove the jumpers Do not use the horizontal
21. able e Linearity 596 PICTURE SIZE REGULATION e 296 VERTICAL SCAN e Frequency 47 Hz to 63 Hz e Linearity 5 GEOMETRIC DISTORTION e 2 max VIDEO CHARACTERISTICS e Bandwidth 3 db 12 MHz typical e Rise Time Less than 50 nanoseconds e Overshoot max 5 MECHANICAL e The 19 monitor is also available in universal mount brackets The monitor can be mounted in the user s cabinet horizontally or vertically Contact your sales representative for details e The standard Prismatic 25 25 monitor is available as a kit without a frame Custom frames can be furnished e The standard Prismatic 9 9 monitor is available as a kit without a frame Also available in chassis form adaptable to individual customer requirements e Contact your sales representative for details USER ADJUSTABLE CONTROLS AND ADJUSTMENTS e Brightness Contrast Horizontal Hold Horizontal Size Horizontal Raster Position Horizontal Video Position Vertical Hold Vertical Size Vertical Raster Position Focus Custom Control Location available POWER INPUT e 120 VAC 10 15 50 60 Hz 85W max Isolation transformer required furnished with monitor as an option ENVIRONMENTAL CONDITIONS e Operating temperature 0 to 55 C Complies with U L C S A and D H H S radiation performance standard composite video RESOLUTIONS e Standard CRT 9 280 Pixels x 240 Lines 13 400 Pixels x 240 Lines 19 40
22. adjustments 3 Insert three rubber wedges to the position as shown in NOTE 1 Tilting the angle of the yoke up and down adjusts the WEDGE crossover of both vertical and horizontal red and blue lines See Fig 8 a and b 2 Tilting the angle of the yoke sideways adjusts the parallel convergence of both horizontal and vertical lines at the edges of the screen See Fig 9 a and b 3 Use three rubber wedges tapered rubber wedges are used for a purpose 4 The position of each rubber wedge is shown in Fig 7 5 Do NOT force the permanent wedges in They are to be inserted until they just make contact with the yoke after FIG 7 the yoke has been positioned 6 Fix the three permanent rubber wedges with chloroprene rubber adhesive 7 After the adhesive has dried enough to hold the wedges in place carefully remove the temporarily installed wedge PPER UPPER B GR d RG B R B 8 R G G CRT m G G CRT B R R B A RGB UNDER BGR UNDER b TEMPORARILY INSTALLEO DEFLECTION YOKE CRT SCREEN a INSERT RUBBER WEDGE CRT SCREEN INSERT RUBBER WEDGE FROM UPPER SIDE FROM LOWER SIDE FIG 8 P i 6 R R B q b CRT SCREEN INSERT RUBBER WEDGE CRT SCREEN INSERT RUBBER WEDGE FROM LEFT SIDE FROM RIGHT SIDE FIG 9 WHITE BALANCE N Equipment Required An oscilloscope with a DC coupled mode in the vertical amplifier Referring to Fig 1 and 3 do the following adjustments in subdued light after degaus
23. bs aligned with each other and pointing up toward the anode contact of the CRT 4 Vertical raster position control must be at the centerofits rotation 5 Remove the R G B signal from the monitor 6 Turn the Green Cut off Control VR203 on the Neck Board fully CW See Fig 1 7 Turn theRed andBlue Cut off Controls VR201 amp VR205 fully CCW 8 Pull the Deflection Yoke backward so that the Green belt will ap pear See Fig 4 P456 VIDEO NECK BOARD FIG 3A lane GAP GRIDS NO 5 AND 6 DZ ZO 1 NOTD PURITY AND CONVERGENCE PURITY ADJ RING ASS Y RED BLU ADJ SHOW IN START ING POSITION RED BLU ON GREEN ADU TOP VIEW RED BLUE ON GREEN n 10 O CLOCK a RED BLUE 2 O CLOCK Q203 0202 Q20 Gi em ii GRIDS BLU ET NO 3 _ GRN mm AND4 P RED l 9 Ii T O N vi R209 N L G P448 VIDEO NECK BOARD PURITY ADJ RED BLUE ADJ RED BLUE VIEW ON GREEN ADJ CONCENTRIC RED BLUE RED BLUE 10 O CLOCK SHOWN IN ZERO CORRECTION POSITION REAR VIE W PURITY PURITY 9 O CLOCRNI 3 O CLOCK INDIVIDUAL FIG 2B TAB ROTATION TEMPORARILY INSTALLED GREEN BELT 5825 FIG 4 9 Decrease the horizontal width ofthe raster if necessary in order to be able to see the right and left edges of the raster 1 ove the two Purity Magnets with respect to each other in order to center the Green belt on the raster horizontally 11 Push the Deflection Yoke forwar
24. d gradually and fix it at the place where the Green screen becomes uniform throughout 12 Turn the cut off and Drive Controls and confirm that each color is uniform 13 If the color is not uniform re adjust it moving the Purity Magnets slightly 14 Turn all three cut off controls fully counterclockwise CCW Slowly turn up CW the Red cutoff control until a Red raster is just barely visible 15 Slowly turn up the Green and Blue cutoff controls such that their associ ated colors mixing with the Red results in a White or Gray raster 16 Confirm that the white or gray color is uniform throughout the screen 17 Insert a wedge temporarily as shown in Fig 4 and adjust the angle of the Deflection Yoke STATIC CONVERGENCE ADJUSTMENT 4 Pole Magnets and 6 Pole Magnets are for static convergence 1 A cross hatch signal should be connected to the monitor 2 A pair of 4 Pole Convergence Magnets is provided and adjusted to con verge the blue and red beams See Fig 6 When the Pole opens to the left and right 45 symmetrically the magnetic field maximizes Red and blue beams move to the left and right See Fig 5 Variation of the angle be tween the tabs adjusts the convergence of red and blue vertical lines 3 When both 4 Pole Convergence Magnet Tabs are rotated as a pair the convergence of the red and blue horizontal lines is adjusted 4 A pair of 6 Pole Convergence Magnets is also provided and adjusted to converge the magenta
25. e control Repeat steps 10 and 11 until good tracking of white bal ance is achieved End with step 10 With the oscilloscope connected to the collector of the lead color video output transistor See Fig 3 adjust the brightness control to obtain the waveform in Fig 10 BLANKING PULSES FIG 10 IOSV O VDC TYPICAL OSCILLOSCOPE WAVEFORM PATTERNS The waveforms shown below were observed on a wide band oscilloscope The input signal was from a crosshatch generator with a horizontal sync frequency of 15 73kHz and a vertical frequency of 60 Hz If the waveforms are observed on an oscilloscope with a limited high frequency response the corners of the pulses will tend to be more rounded than those shown and the amplitude of any high frequency pulse will tend to be less Each photograph is numbered These numbers correspond to the circled numbers on the schematic diagrams Photographs 12 13 14 15 and 16 are of the red signal at various points along the red video channel The waveforms at corresponding points along the green and blue video channels will look similar sasana Fono dp a lt AS a i am 2V DIV 20 uSEC DIV 2V DIV 10 uSEC DIV 0 5V DIV 20 uSEC DIV 0 2V DIV 5MSEC DIV 10V DIV SMSEC DIV 2V DIV 20 uSEC DIV 1V DIV 20 uSEC DIV 0 5V DIV 10 uSEC DIV E ann ant Mid Tue ua ue HHI wo US AAA MEI wass MWAN buc BOREREND CN 20V DIV 20 uSEC DIV 0 5V DIV 20 uSEC DIV 5V DIV 20 uSEC
26. ft edge This is called retrace Dur ing the second half cycle of the oscillation of C36 and the yoke windings the voltage at the Q11 collector tries to go negative or below ground When this happens the damper diode include in same package with Q11 becomes forward biased The conduction of the damper diode allows energy stored in the horizontal system to decay linearly to zero thus allowing the beam to return to the center of the CRT face The focus voltage and the screen G2 voitage are obtained om the anode voltage with a resistor divider network with in the T1 assembly An auxiliary winding pin 10 provides feedback to the horizontal AFC through R71 R70 and C29 This signal is also used to furnish the horizontal blanking input to IC1 via C28 R69 and R68 The signal from the aux iliary winding at pin 5 of T1 is rectified by D14 and filtered to provide the 12VDC supply for the video interface and sync circuits The auxiliary winding of pins 3and 4 produces a signal which is rectified by D13 and filtered to produce the 24VDC supply for the vertical output circuit The horizontal linearity coil L2 is a magnetically biased coil which shapes the yoke current for optimum linearity The horizontal size coil L1 is a variable series inductor which is used to vary the horizontal size of the display HIGH VOLTAGE HOLD DOWN CIRCUIT The high voltage hold down circuit is part of the main PC board P447 of this monitor The 12V DC s
27. g a large current through the degaussing coil and then having the current decay to zero is what produces the degaussing action The degaussing current decays to zero before the CRT warms up so the degaussing is completed before the picture comes on RT MEER RET ee E EA RES LET AT E 4 TYPICAL DC VOLTAGES WITH INPUT SIGNAL Voltages shown below are for reference only Voltages may vary with input signal and with control adjustment DO NOT MEASURE TRANSISTOR NUMBER Q2 Q3 Q5 Q7 Q10 Q11 Q201 Q202 Q203 ws fv v7 anou oz oze 128 FOE CNN ROO O EO O O EE ICS ate DO NOT MEASURE DIODE NO ANODE CATHODE D1 8 5 9 1 eo fa fofa a TERMINAL NUMBER 6 8 2 6 7 23 6 2 0 0 6 0 8 2 4 0 5 0 2 0 0 3 24 0 2 7 0 9 2 2 2 7 so 1 3 0 3 O O OO N OQO O A wm N 10 4 6 2 439 0 6 N 0 1 3 W 0 55 12 0 2 1 13 7 VI 10 5 0 8 O 12 0 12 8 M 1 7 3 0 1 7 3 0 1 7 0 W NO N NO N G B a 5 ee ICI ING IC4 CONTROL E EM fr co WIDTH ee BOOSTER ls ADJ FIG 11 MAIN PC BOARD LAYOUT 1 NOD 1H9TI48 Q10H A IZIS A SOd A 10H H BBB is XS8 mme VIMOS SOd H 3100 9120 996 23904 O 27
28. hold control for hori zontal centering See 5 NOTE If the sync signal is composite use the horizontal sync input of the same polarity as the composite sync signal HORIZONTAL VIDEO SHIFT CONTROL VR1 Use this control to center the picture horizontally HORIZONTAL RASTER POSITION ADJUSTMENT If the picture is off center horizontally long dimension of picture tube some compensation can be made by moving the horizontal raster position adjustment jumper either to positions R or L HORIZONTAL SIZE COIL L1 The horizontal size coil is a hexagonal tuning tool adjust ment This control must be adjusted slowly if necessary until the picture or test pattern attains the correct hori zontal proportions VERTICAL HOLD CONTROL VR5 Adjust this control until the picture stops rolling and it locks in vertically 50 60 Hz CONTROL VR9 This control is used to limit the range of vertical size This control is preset at the factory and should not require re adjustment unless the vertical size control or vertical hold control are readjusted from their original factory setttings In order to set this control first adjust the vertical size con trol so that the picture is slightly larger than desired Turn VR9so that any vertical foldover which may be present will disappear If the monitor is to be operated alternately at more than one vertical frequency then perform this adjust ment at the higher frequency VERTICA
29. necessarily the one shown in Figure 2 The correct starting position will vary from ring assemblies from one manufacturer to another It will be necessary to determine the correct starting position also known as the zero correction position Figure 2 shows a ring assembly in which each of the rings of the purity ring pair has two tabs one long and one short With some ring assemblies of this type the zero correction position is with the long tab of one ring aligned with the short tab of the other ring On other ring assemblies of this type the zero correction position is with the long tab of one ring aligned with the long tab of the other ring The way to determine which is which is by trying one of these orientations and then rotating the two rings together as a pair without changing their orientation with respect to each other If this rotation of the ring pair causes no change in the purity then itis the zero correction position If the purity does change then try the other orientation A third type of ring assembly has only one tab on each of the two purity rings The zero correction position forthis type ofassemblyis with the tabs of the two purity rings aligned with each other and pointing up toward the anode contact of the CRT Thecorrect starting positions forthe otherring pairs are as shownin Figure 2 For the other type of ring assembly not shown the cor rect starting position for the other two ring pairs is with all of the ta
30. ovide the Q11 base circuit with the low impedance source that it requires The horizontal output transistor Q11 is operated as a switch It is either on or off It is turned on and off at the scan rate which is determined by the horizontal oscillator frequency which is ultimately determined by the incoming horizontal sync frequency A yoke current with a sawtooth waveform is needed to deflect the beam linearly across the CRT The beam begins at the center of the CRT and is deflected from center to right This center to right deflection occurs when Q11 is turned on The deflection yoke coupling capacitor C38 also known as the S shaping capacitor begins to dis charge through the yoke the discharge current causes the beam to be deflected to the right CRT edge At this time Q11 is turned off and the current provided by C38 stops As the current falls to zero a voltage is induced across the yoke windings as the magnetic field collapses an oscilla tion is produced by the yoke windings and C36 the retrace tuning capacitor During the first half cycle of oscillation the induced voltage is impressed on the collector of Q11 C36 and the primary of they flyback transformer T1 This induced voltage is stepped up by the flyback transformers secondary winding This high voltage is then rectified and appliedtothe high voltage anode of the CRT When this induced voltage occurs the electron beam is deflected from the right edge of the CRT face to the le
31. red blue to green beams See Fig 6 When 2 Pole opens to the left and right 30 symmetrically the magnetic field is maximized Red and blue beams both move to the left and right See Fig 5 Variation ofthe opening angle adjusts the convergence of magenta to green vertical lines 5 When both 6 Pole Convergence Magnet Tabs are rotated as a pair the convergence of magenta to green horizontal lines is adjusted ANODE CONTACT RUBBER WEDGE YOKE FIG 6 6 POLE CONVERGENCE MAGNETS 4 POLE CONVERGENCE MAGNET PURITY CENTERING MAGNETS MAGNET ASS Y DEFLECTION GREEN GUN IS THE CENTER GUN CONVERGE THE REO ANO BLUE THEN CONVERGE RED AND BLUE ON GREEN VERTICAL CONVERGENCE BLUE amp RED HORIZONTAL CONVERGENCE BLUE amp RED 3 ROTATE BOTH MAGNETIC RINGS TOGETHER VERTICAL 6 POLE CONVERGENCE MAGNETS BLUE amp RED ON GREEN 4 SLIDE MAGNETIC RING TABS TOWARD OR AWAY FROM EACH OTHER L lm IS f RED BLU RED BLU f HORIZONTAL 6 POLE CONVERGENCE MAGNETS BLUE Q RED ON GREEN 5 ROTATE BOTH MAGNETIC RINGS TOGETHER REPEAT 3 28 3 3 IF ALL LINES ARE NOT CONVERGED AT CENTER FIG 5 CONVERGENCE PRECISE ADJUSTMENT OF DYNAMIC CONVERGENCE 1 Feed a cross hatch signal to the monitor 2 Insert wedge temporarily and fix the Deflection Yoke so as to obtain the best circumference convergence See Fig 8 and 9 NOTE The wedges may need to be moved during
32. ry for most video signals since they already have an interruption of video blanking between scan periods Some do not it is to ac commodate such signals that the forced blanking circuit is included The red green and blue signals go into IC1 at pins 2 4 and 6 Their levels are controlled by the gain of separate channels of the contrast amplifier The gain is controlled by a DC volt age input to pin 11 which varies with the setting of the con trast control IC1 provides blanking of the video during retrace in response to blanking pulses at pin 13 derived from the horizontal and vertical sweep circuits IC1 also requires a gating signal at pin 12 in order to provide red green and blue outputs at pins 21 19 and 17 If the gating signal is not present IC1 will not provide video output signals The gating signal comes from IC2 pin 12 and is derived from horizontal sync The brightness is varied by varying the DC level of the out puts at pins 17 19 and 21 This is accomplished by varying the DC voltage input to pin 14 The video outputs from IC1 are provided via R30 R31 and 2 to the neck board where they are amplified by the video output stages Q201 Q202 and Q203 before being applied to the cathodes of the CRT through R10 R11 and R12 SYNC Sync is applied at P1 positive sync or at P2 negative sync Composite sync should be applied only to the horizontal sync input of the appropriate polarity Positive sync is
33. sed during the first two weeks of July Telephone assistance is not available during this period Before calling be sure to have available the model number of the monitor being serviced and the schematic diagram of the monitor being serviced Replacement parts may be ordered from the Service Department between 7 00am and 4 30pm Central Time All monitors are equipped with automatic degaussing coils which demagnetize the picture tube every time the monitor is turned on after being off fora minimum of 20 minutes Should any part of the chassis become magnetized it will be necessary to degauss the affected area with a manual de gaussing coil Move the coil slowly around the CRT face area and all surrounding metal parts Then slowly withdraw for a distance of 6 feet before turning off Horizontal vs Vertical Some models have the picture tube mounted vertically rather than horizontally That is the picture tube is mounted in the frame such that the long dimension of the tube is up and down Examples of this include but are not limited to Models 13K7851 and 19K7951 Other than the physical orientation of the picture tube there is no electrical difference between these models and their horizontal counterparts The same circuits the vertical circuits produce and control deflection along the short dimension of the tube in all models The same circuits the horizontal circuits produce and control deflection along the long dimension of the
34. sing and setting the purity of the CRT Ground theR G B video inputs Apply sync signals to the sync inputs Set all three drive controls VR202 VR204 amp VR206 to their midpoints of rotation Set the screen and R G B cutoff controls to their mini mum fully CCW positions Connect the oscilloscope to the collector of a video out put transistor Q201 Q202 or Q203orto the end of R207 R208 or R209 indicated on Figure 3 as Red Green or Blue If this white balance procedure is required because the CRT or neck board was replaced then leave the con trast control at its original setting If the contrast con trol is known to be grossly out of adjustment then set it to its center of rotation Adjust the brightness control VRG to obtain the waveform shown in Figure 10 Now remove the scope probe 8 Slowly turn the screen control CW until the raster is just visible The color of this raster is called the lead color gun DO NOT adjust its associated cutoff control It must remain fully CCW 9 Adjust the screen control CCW until the raster is just extinguished 10 Adjust the brightness control for a dim raster Adjust the two remaining cutoff controls NOT the lead color gun cutoff control for best gray uniformity 11 Adjust the brightness control for a bright raster but not 12 13 maximum brightness Adjust the R G drive controls if necessary for best neutral white Try not to adjust the blue driv
35. upply is sensed via D10 Since the 12V DC supply is flyback pulse derived the 12V DC supply will rise as the high voltage rises If the 12V DC exceeds a threshold which is set with VR8 then D12 will conduct thereby providing drive to IC2 pin 5 holddown input of deflection oscillator IC The drive being applied to pin 5 causes the horizontal oscillator within the IC to shut down thus preventing the generation of high voltage The horizontal oscillator will remain in its OFF state even the input to IC2 pin 5 is removed unless and until AC power is removed from the monitor input The power may then be reapplied VERTICAL OSCILLATOR AND OUTPUT The composite sync ouput of IC2 pin 12 is filtered through the network of R65 C25 C24 and R66 so that only vertical sync is applied to the vertical trigger input at pin 11 The verti cal oscillator frequency is controlled by the vertical hold con trol and its input to pin 10 The vertical drive output at IC2 pin 7 is applied to pin 4 of IC3 the vertical output IC Output current from IC3 pin 2 flows through the yoke to cause vertical deflection During upward deflection current flows out of pin 2 through the yoke and into C50 to charge it Downward deflection is caused by C50 discharging through the yoke in the opposite direction and back into IC3 pin 2 AC feedback is provided through the wiper of the vertical size control VR4 to IC2 pin 8in order to control the drive amplitude D
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