Zenith SM-ZVM-122, Service Manual

Page 1: ...Copyright 1983 Zenith Data Systems All R gt ts Reserved SM ZVM 122 123 Video Monitors Service Manual aN data systems SAINT JOSEPH MICHIGAN 49085 585 33 01 Printed in the United States of America ...

Page 2: ...rd in place It slides into slots which are molded into the cabinet and the cabinet back holds it in place SAFETY CHECK After the original service problem has been cor rected check for the following FIRE SHOCK HAZARD 1 Be sure that all components are positioned in such a way to avoid the possibility of adjacent component shorts This is especially impor tant on those chassis which are transported to...

Page 3: ...nt Monitor is the picture tube How ever this tube does not emit X rays when the 2 III earth ground water pipe conduit etc and the exposed metallic parts one at a time Mea sure the AC voltage across the combination 1500 ohm resistor and 0 15 JLF capacitor Re verse the AC plug and repeat AC voltage mea surements for each exposed metallic part Voltage measured must not exceed 0 75 volts rms This corr...

Page 4: ...part ment and all metal shields where used must be kept in place whenever the chassis is operating If a shield is missing it should be replaced at once as a standard servicing pro cedure TIPS ON PROPER INSTALLATION 1 Never install a Monitor in a closed in recess cubbyhole or closely fitting shelf space 2 3 4 5 6 Never install a Monitor over or close to a heat duct or in the path of heated air flow...

Page 5: ... 1 1 Service Procedures 6 1 Specifications 2 1 Replacement Parts List 7 1 Installation and Set Up 3 1 Semiconductor Identification 8 1 Theory of Operation 4 1 Circuit Board X Ray Views 9 1 Disassembly 5 1 Schematic Diagram fold out ...

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Page 7: ...al Hold and Vertical Height These Monitors are certified to comply with the limits for class B computing devices pursuant to sub partJof part 15 of the FCC rules Service of these monitors is to board level When you have determined that a circuit board is at fault it must be replaced Return the defective board to your Zenith Data Systems Distributor You will need the folowing tools and test equipme...

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Page 9: ...acter Width 120 VAC 60Hz 0 3 Amps 28 Watts 13 okV 4 0 Amp type FX3201 Standard 15 MHz 50 nanoseconds 12 diagonal ZVM 122 Amber ZVM 123 Green 8 x 10 matrix 40 or 80 per line Zenith Data Systems reserves the right to discon tinue products and to change specifications at any time without incurring any obligation to incorporate new features in products previously sold Page 2 1 ...

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Page 11: ...se vents are not blocked CABLE DESCRIPTION The video output cable from the computer to the Video In jack on the Monitors is a single conductor cable HE 134 1319 Refer to Figure 3 1 for cable connection to the Monitor WIDTH CONTROL The Width control is soldered to the input board and is accessible from the rear panel Refer to Figure 3 1 40 80 CHARACTER SWITCH The 40 80 Character switch is an SPST s...

Page 12: ...he Vertical Size control is located on the front of the Monitor behind the access door Refer to Figure 3 2 VERTICAL SIZE VERTICAL HOLD CONTROL The Vertical Hold control is located on the front of the Monitor behind the access door Refer to Figure 3 2 HomZONTALHOLDCONTROL The horizontal hold control is located in front of the monitor behind the access door Refer to Figure 3 2 ON OFF SWITCH The ON O...

Page 13: ...lity to switch from a regulator to an active filter at low line volt ages The voltage at the collector of Q702 is propor tional to the available input voltage to the regulator When the input is too low to maintain 12 7 volts the voltage at the collector of Q702 drops below the reference zener voltage causing CR705 to conduct This additional current sinking through R701 dis ables the zener referenc...

Page 14: ...positive going fly back pulse from the emitter charges C606 and C60B through Q601 The capacitors discharge through their respective resis tor networks Capacitor C606 discharges during the trace interval to 0 6 volts below the emitter voltage of Q601 At this point Q601 conducts and turns off the amplifier stages This causes the yoke voltage to fly up and repeat the cycle The presence of a sync sign...

Page 15: ... to a trip voltage set in the inte grated circuit When this trip voltage is reached the capacitor is discharged to a new trip value This pro cess is repeated producing a sawtooth waveform The output of the phase detector controls the oscil lator through resistive coupling from pin 5 to pin 7 The Horizontal Hold control is also connected at pin 7 The two 100 kfl resistors in the horizontal hold cir...

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Page 17: ...the back cover Remove the power cord from the power source Disconnect the video cable Remove the three screws A Remove the two screws B across the bot tom Remove the one screw C on the rear panel Slide rear panel through its opening to re move it from the back cover Remove the back cover J 1111111111111111111111111111111111 m Figure 5 1 Back cover removal ...

Page 18: ...trols are mounted to circuit board which is secured to the front of the main chassis To remove this board Remove the back cover Remove the input transformer assembly Remove the main board Remove the three screws E that secure the board to the front panel Remove the board ON OFF SWITCH Refer to Figure 5 2 The On Off switch is located on the front panel To remove this switch Remove the back cover Re...

Page 19: ...o o Q FU SE I_A_ _ _ _ _O__ _ _J FUSE JUST I It I f 1m Figure 5 2 Component removal Page 5 3 ...

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Page 21: ...ach to diagnosing the problem If you encounter a problem not listed in this chart analyze where the problem is located by the way the circuits relate to each other AREA TO CHECK Line cord and power source Fuse FX201 or FX701 Transformer TX201 SWitch SX201 or wiring at switch Shorted diode CR701 CR704 Q701 o703 or associated circuitry LED open CX707 R707 and R706 interchanged CR701 CR704 one open C...

Page 22: ...U190 you may use the Display Keyboard Test to fill the screen When the prompt appears type T Select the Keyboard Test Type any character and it will fill the screen Press the DELETE key to exit AREA TO CHECK 0601 0602 0603 0604 0606 Yoke TX202A open Yellow and black wires on yoke interchanged Red and blue wires on yoke interchanged 0801 0802 C8010pen 0806 0805 Wiring between boards ZBASIC PROGRAM ...

Page 23: ...el Refer to Figure 6 1 Adjust this control as required for a stable display VERTICAL SIZE Page 6 3 VERTICAL HOLD The Vertical Hold control is located behind the front access panel Refer to Figure 6 1 Adjust this control as required for a stable display VERTICAL SIZE The Vertical Size control is located behind the front access panel Refer to Figure 6 1 Adjust this control so the display is equal on...

Page 24: ...just this control so the display is equal on both sides The Character switch is located on the rear panel Refer to Figure 6 2 Set the character switch for 40 or 80 characters per line 1111111111111111111111111111111111 40 80 CHARACTER SWITCH D il Ji l t n WIDTH CONTROL e Figure 6 2 Rear panel VIDEO CABLE CONNECTION ...

Page 25: ...DJUSTMENT The B adjustment is located on the main board o Page 6 5 at RX709 To adjust B voltage remove the rear cover Then connect your voltmeter to ground and the positive lead to the B side of RX709 Refer to Figure 6 3 Adjust the control for 12 7 VDC CRT CENTERING MAGNETS The CRT Centering magnets are located in front of the yoke on the neck of the CRT Refer to Figure 6 3 Adjust the centering ma...

Page 26: ...lent reference for sync and video signals Video Input Figure 6 4 Video input Video Output Q201 Figure 6 6 Video output 5 v div 5 ms div 10v div 5 ms div Video Driver Q805 Figure 6 5 Video driver Vertical Oscillator Q601 Figure 6 Vertical oscillator 1 v div 5ms div 2 v div 5 ms div ...

Page 27: ...pe numbers Example 74LSI53 refer to the Semiconductor Identification Chart t1 l 4V 602 Clltl ik 1 0604 IIV VERT OUTPUT I 623 0 RIll 1 1 0603 11 R607 0601 C611 VERT T1 4V J x I I MEG VERT T 0602 AM _l 0606 I I w OSC cooo VERT AM VERT I I L J jt OUTPUT II 02 o 0 C608 R613 1 G JIi _ro j1 i o1_ _I C 4 J 1 6201 1l R821 L F N6 609 271 1 f V Sll 4 J 8 12 4 B 24V VERT BLANK L __ l_ _ _ _ _ _ _ _ _ _ _ _ _...

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Page 29: ...S HE 234 333 300 kll vertical size control R501 HES 221 12 220ll RS18 HES 103 12 10 kll R502 HE S 222 12 2200ll RS19 HES 473 12 47kll R503 HES 103 12 10kll RS20 HES 331 12 330ll R504 HES 123 12 12 kll RS21 HES 273 12 27kll R505 HES 105 12 100 kll RS22 HES 243 24kll R50S HES 153 12 15 kll RS23 HES 1oo 12 1ll R507 HES 270 12 27ll RS24 HE S 689 12 6 8 II R508 HE 6 333 12 33kll RS2S HES 132 12 1 3 kll...

Page 30: ... pF R822 HE S 221 12 2200 CX514 HE 234 403 027 F R823 HE 6 681 12 6800 C515 HE 21 140 001 F R824 HE 6 272 12 27000 C51S HE 234 401 10 F R825 HE 6 273 12 27kn C517 HE 25 861 220 F R82S HE 6 752 12 7500kn C518 HE 234 408 4 7 F R827 HE 6 105 12 1 MO 10 C519 HE 21 56 4700pF R828 HE 6 273 12 27kO C520 HE 234 401 10 F R829 HE 6 511 12 5100 C521 HE 21 56 4700pF R830 HES 333 33 kn 10 1 2 watt C522 HE 25 9...

Page 31: ... 234 387 Width coil LX508 HE 234 342 Choke coil TX201 HE 234 385 Power transformer TX202 HE 234 386 Deflection yoke T501 HE 234 350 Transformer horizontal driver TX502 HE 234 398 Sweep transformer Page 7 3 MISCELLANEOUS IC501 HE 234 368 Horizontal processor IC E201 HE 234 336 Spark gap E202 HE 234 336 Spark gap E203 HE 234 336 Spark gap E204 HE 234 336 Spark gap FX701 HE 234 366 Fuse normal lag 2 ...

Page 32: ...inet front Cabinet rear Plastic rail left Plastic rail right Power supply bracket Control cover One conductor video input Line cord HE 234 390 HE 234 391 HE 234 393 HE 234 388 HE 234 389 HE 234 392 HE 234 394 4 24 x 312 screw 6 20 x 312 screw 6 20 x 375 screw 6 20 x 5 screw 8 18 x 625 screw 8 18 x 75screw 8 18 x 625 screw SEMICONDUCTORS See semiconductor identification ...

Page 33: ...504 103 295 02 CR506 103 261 04 CR507 HE 234 299 CR508 103 263 CA509 103 295 CR601 103 142 01 CA602 103 142 01 CR603 HE 234 299 CA604 HE 234 299 CR605 HE 234 299 CAX701 HE 57 42 CAX702 HE 57 42 CAX703 HE 57 42 CAX704 HE 57 42 CR705 HE 234 299 CA706 103 279 09 CR801 103 142 01 CA804 103 142 01 CA805 103 142 01 CIRCUIT ZDS COMPo NO PAAT NO Transistors 0501 OX502 0601 0602 Q603 Q604 0606 0607 0701 07...

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Page 35: ...same number in the Circuit Compo nent Number column A Find the circuit component number Cl0l Rl04 etc on the proper X ray View C Adjacent to this circuit component number you will find the ZDS PART NUMBER CONTROL PANEL BOARD Shown from the component side CRT SOCKET BOARD Shown from the component side INPUT BOARD Shown from the component side MAIN BOARD Shown from the component side ...