Zanussi 22ZT907 Service Manual Download Page 3

Page: 3 / 64

CONTENTS

GENERAL FEATURES

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CONTROLS ON THE RECEIVER

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ACCESS TO INTERNAL COMPONENTS

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VIEW OF CHASSIS AND OF DISCONNECTED

PLUG-IN TYPE P.C.BOARDS

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REFERENCES FOR MAIN ADJUSTMENTS

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TRANSISTORS

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INTEGRATED CIRCUITS

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MAIN COMPONENTS

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ADJUSTMENT PROCEDURE

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TELETEXT TRANSMITTER

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PROCUCT SAFETY NOTICE

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Summary of Contents for 22ZT907

Page 1: ...TIP ZANUSSI ZANUSSI Model Chassis 22ZT907 BS 400 2 CHASSIS ZANUSSI SERVICE MANUAL ...

Page 2: ...ETCO ACF Model 22 ZT 907 C 430 2 1982 UK 54 Zanussi Elettrorrica S p A reserve all legal rights to the exclusive ownership of this document and hereby prohibit reproduciion or disclosure of the same without their prior permission ...

Page 3: ...ACCESS TO INTERNAL COMPONENTS 4 VIEW OF CHASSIS AND OF DISCONNECTED PLUG IN TYPE P C BOARDS 5 REFERENCES FOR MAIN ADJUSTMENTS 6 TRANSISTORS 8 INTEGRATED CIRCUITS 10 MAIN COMPONENTS 12 ADJUSTMENT PROCEDURE 16 TELETEXT TRANSMITTER 24 PROCUCT SAFETY NOTICE 33 ...

Page 4: ...ctronic voltage synthesis type 16 TV programmes and VCR on programme 16 Insertable through pushbutton IR type Max range approx 8 m TRANSMITTER In stand by 20 uA In operation 9 mA Electronic programmable type with digital hours and minutes indication AUXILIARY OUTPUT JACKS LOUDSPEAKER AUDIO OUTPUT STANDARD DEGAUSSING DIMENSIONS WEIGHT Headphones jack 8 Ohm DIN 45327 Tape recorder 47 kOhm DIN 41524 ...

Page 5: ...trol receiver 8 Clock brightness control 9 Clock reset hours H 10 Clock reset minutes M 11 Volume 12 Tone control treble 13 Tone control bass 14 Brightness 15 Colour control 16 Contrast 17 Clock programmer 18 UHF band indicator light 19 AFC indicator light 20 AFC pushbutton 21 Station scanning control S 22 Fine tuning regulation 23 Tuning sequence lights 24 Recording jack 25 Output jacks foldback ...

Page 6: ...Rear sockets 27 Auxiliary speaker jack 28 Aerial socket 29 Clock battery recess 3 ...

Page 7: ..._ i ACCESS TO INTERNAL COMPONENTS To remove back panel 1 Insert a blade screwdriver into A 2 Push down retaining lug B 3 Release bottom part and remove panel i a_ ...

Page 8: ...PE P C BOARDS BS 400 LEGEND BS 400 2 BS 417 BS 395 BS 396 BS 418 BS 399 BS 398 BS 397 Chassis Power supply p c b Line output p c b Synchro separator and pincushion correction p c b CRT discharger p c b Video p c b IF unit p c b Vertical deflection p c b A BS 417 BS 395 BS 396 5 ...

Page 9: ...l amplitude adjustment potentiometer Raster adjustment potentiometer Potentiometer for grid 2 adjustment of picture tube CRT discharger p c b Switch for blue electron gun Switch for green electron gun Focus adjustment potentiometer Switch for red electron gun Power supply p c b Potentiometer for adjustment of 12 6v DC Potentiometer for adjustment of 15OV DC Oscillator frequency adjustment potentio...

Page 10: ... b Video p c b Peak to peak adjustment potentiometer blue Black level adjustment potentiometer blue Peak to peak adjustment potentiometer green Black level adjustment potentiometer green Peak to peak adjustment potentiometer red Black level adjustment potentiometer red Potentiometer for adjustment of direct signal level Burst phase adjustment coil Capacitive trimmer for oscilloscope adjustment ...

Page 11: ...cillator convertor UHF UHF amplifier IF amplifier Audio amplifier Impedance matcher Automatic control of p p luminance signal Brightness control fixed level setting for adjustment of the output video amplifiers T 101 driver Suppressor of unwanted reflections on the burst signal delay line LR 102 of the chrominance channel Active load Video output Active load Video output Active load Video output O...

Page 12: ...T 803 BC 413 C Amplifier T 804 BC 253 C Amplifier T 805 BC 170 C T 806 BC 320 B T 807 BC 320 B T 808 BC 320 B Square wave shaping Driver for display s lit spot Driver for display s lit spot Driver for display s lit spot T 809 T 8i0 T 811 T 812 T 813 BC 548 B BC 548 B BC 320 B BC 548 B BC 548 Colour adjustment Volume adjustment Muting Muting Output impedance matcher T 814 T 815 BC 548 BC 548 Output...

Page 13: ...rocessing Brightness contrast and colour controls Beam current limiter Colour subcarrier regeneration PAL switching Identifier Killer AFC and automatic phase control ACC Burst TDA 2161 R Y B Y demodulators G Y matrix Luminance matrix Continuous path control adjustment of treble bass and volume TDA 2030 TDD 1618 MC 14013 Audio amplifier l8V stabilizer Switch ON reset TV start signal 24h clamp pulse...

Page 14: ...4429 UAA 1008 4071 BE 4049 D 4013 SN 16889 P SAA 1051 SAA 1050 Electronic functions It drives DI 651 display Memory for 8 programmes Memory for 8 prograinmes Control unit Band decoder Coincidence detector Operational amplifier AFC processing Two input OR Inverting buffer Double flip flop Tuning indicator It processes information coming from remote control Remote control transmitter ll ...

Page 15: ...s the audio signal not adjusted in volume coming from p c b BS 398 it adjusts it in amplitude and tone it amplifies it and sends it to drive the two receiver s loudspeakers tweeter and woofer Through jack PR 201 it is possible to connect externally an auxiliary 2 7 Ohm loudspeaker with or without the exclusion of the internal loudspeakers Furthermore the p c b transferes the audio signal not adjus...

Page 16: ... a voltage proportional to the beam current BS 396 Synchro separator and pincushion correction p c b The p c b processes the video signal Said process consists in separating the horizontal signals from the video composite signal The pincushion correctionl section receives a sawtooth shaped signal and converts it into a parabolic shape for E W correction BS 395 Horizontal deflection p c b This p c ...

Page 17: ... p c b It converts IR pulses coming from the transmitter into electrical pulses These are amplified and appropriatly clipped No adjustments needed BS 389 Remote control receiver p c b It receives the command signals coming from the sequential programme pushbutton it processes them and converts them into control signals Tone and contrast controls also pass through this p c b said control signals be...

Page 18: ...nd decrement Inclusion exclusion of the AFC circuit with LED display Band indication displayed on three LEDs Tuning level indication with five LEDs Memorization of 16 selected programmes manually or with remote control No adjustments needed BS 414 a b Remote control p c b This p c b enables remote control of the following functions selection of 16 programmes or volume adjustment brightness and sat...

Page 19: ...pe 10 MHz pass band IF signal video carrier 39 5 MHz and audio carrier 33 5 MHz with 100 standard video modulation bar modulating signal 20 white level 76 black level Audio carrier modulated at 1 kHz with 50 kHz of deviation at 50 us of preemphasis Voltmeter 15V setting Note See legend of test points TP at the end of adjustment procedure Preliminary operations Supply the p c b with 12 6V at termin...

Page 20: ... probe on collector of T6 See figure below 6PF SFD104 390 r q q _ 1 ADJUSTMENTS Adjustment of RF unit output filter l Adjust L40 and L49 for a curve as that shown in figure corresponding to best coupling and balancing 37 125Mt k ______ I _ J 30MHz _ 3d6 _ _ _ 2 Disconnect the probe from collector of T6 IT ...

Page 21: ...e a max 12V bias to the volume control terminal A 2 3 Connect a 10 kOhm resistance between pin 13 of TBA 120 U and the 12V and read the DC voltage 4 Disconnect the 10 kOhm resistance 5 Adjust L47 until the DC voltage corresponds again to value measured previously Audio adjustment l Move the oscilloscope probe to terminal A 3 2 Maintain on the TP 1 the IF signal with modulated audio carrier 3 Adjus...

Page 22: ... AGC voltage for RF unit l Connect a voltmeter to TP 5 2 With the signal at 15 mV video IF adjust P 1 until voltage is reduced to 8V Correspondence between TP test point and wiring diagram TP 5 R50 51 node TP 1 L20 24 node 1 g ...

Page 23: ...o Oscilloscope s Adjust P107 to Oscilloscope s Adjust PlO9 to probe on red output H4 set the reference level see figure 4 to 170V DC probe on green output H2 set the reference level to 170V DC probe on blue output Hl position the reference level to 170V DC Colour bar signal in antenna Correct tuning Saturation to max Oscilloscope s probe on TP102 Apply a 1 V DC voltage to TP103 Adjust LlOl for max...

Page 24: ...eference the colour of the prevailing electron gun of this line accurately adjust black level potentiometers of the other two electron guns P105 for red P107 for green P109 for blue until the horizontal line is perfectly white Adjust P551 up to the point in which the white line fades out cut OFF Reconnect SW501 If a predominance of a colour is noticeable on the screen eliminate it by re adjusting ...

Page 25: ... the test picture are straight Adjust P 403 to obtain a correct horizontal amplitude PCB BS 393 Denomination Picture tube Adjustment procedure SW 551 552 553 Switches for exclusion of picture tube electron guns P 551 Grid 2 adjustment of picture tube P 552 Focus adjustment PCB BS 417 Denomination Adjustment procedure Power supply Adjust P 301 to obtain 150 V DC at terminal N 5 Adjust P 303 to obta...

Page 26: ... Adjust P 352 to obtain a correct frame synchronization Grossly adjust vertical centering P 354 vertical amplitude P 353 and linearity P 351 Adjust P 354 for correct picture centering Adjust P 353 to obtain a correct vertical amplitude Adjust P 351 to obtain the best vertical linearity 23 ...

Page 27: ...l in MIX and CANCEL operations Superimposes teletext on to normal television programme on the screen This command displays concealed information as long as the button is depressed Used for quizzes puzzles etc This allows an Alarm Page I to be received at a predetermined time Select the page number required and press TP ON TOO00 will appear at the top right hand corner of the screen Select the requ...

Page 28: ...n large characters Commands TEXT HOLD TP ON TP OFF restore the mode into the upper half page FULL Restores the character size to normal CANCEL This command suppresses the TEXT display restores Video picture while the system remains in Teletext mode giving the possibility of selecting Pages using TP ON Alarm pages TEXT and MIX will cancel the command PICTURE Returns to TV picture from Teletext mode...

Page 29: ...BC 548 B BC 548 B BC 548 B BC 548 B BC 548 B BC 548 B BC 548 B Video preamplifier Video preamplifier Video input signal switch T3 switch enabler Teletext synchro switch Synchro signal emitter follower Command inverter B signal emitter follower C signal emitter follower R signal emitter follower Blanking signal emitter follower Brightness signal emitter follower 25 _ ...

Page 30: ... SN 74 LS 161 AN SN 74 LS 161 AN MCM 21 L 14 C 45 MCM 21 L 14 C 45 SAA 5050 TROM GB Electronic functions 12V stabilizer 5V stabilizer Programmable adaptor for teletext Teletext video processor Teletext acquisition and control circuit Teletext timing chain circuit Two input NOR 4 bit adder 4 bit synchro counter 4 bit synchro counter 4096 bit static RAM 4096 bit static RAM Teletext ROM character gen...

Page 31: ...eletext information and transfers data into memory CI 11 and CI 12 it generates timing signals for displaying and reading data stored in memory CI 6 It converts data retreived from memory into video signals to be forwarded to the CRT CI 13 it supplies blanking and synchro pulses to be forwarded to the TV set synchro separator when teletext information is diplayed The p c b is supplied with 5V and ...

Page 32: ...video input processor SAA 5030 is adjuted through trimmer PlT The video signal phase TP8 and in particular the portion including the vertical synchro signal must be compared on the oscilloscope against the output signal taken from contact 13 of IC SAA 5030 TP 10 The trimmer is adjusted so as to delay the leading edge of the video signal pulse on contact 13 48 2 5 H with reference to the start of t...

Page 33: ...ans of this resistance from approx 0 5 kHz to over 6 MHz this assuring that signal quality detector provided in circuit SAA 5030 operates in the best manner B Method For capacitive trimmer adjustment it is also possible to use the same teletext reproduction Once again it is necessary to connect the short circuiting jumper and the 5 6 MHz resistance as described above By means of remote control the...

Page 34: ...loscope s probe to pin 18 of SAA 5030 CLOCK output and synchronize it externally with clock signal of teletext generator Adjust L4T for a stable clock signal Final check Select page III check for completeness and exactness of the heading line and of page characters Check functions of TELETEXT transmitter Testing of teletext p c b 1 Check supplies a 12 5 61 280 mA b 5V z 5 TP5 380 mA 2 Test transco...

Page 35: ...l 2 Adjust P2T on B so that the character reaches the 110 V DC level 2 11OV DC____ B level Yj Line blanking 1OOV DC R G levels _ _ 0 V DC Fig 2 I a After white adjustment visually inspect that white characters have correct tint otherwise retouch one or two of the potentiometers P2T P3T and P4T reducing amplitude of dominant colours so as to obtain characters having correct white 32 ...

Page 36: ...ing servicing Therefore the following checks are recommended for the continued protection of the customers and service technicians INSULATION Insulation resistance should not be less than 2 MOhm at 500 V DC between the mains poles and any accessibe metal parts HIGH VOLTAGE High voltage should always be kept at rated value of the chassis no higher Operating at higher voltage may cause a failure of ...

Page 37: ... ___ 7 6 i _ _ _ _ _ _ __ _ _ _ The Manufacturers reserve all legal ri z to the exclusive ownership of this document and hereby prohibit reproduction or disclosure of the 8ame without their prior permission _ 46 0011 23456789101112 8 2 ...

Page 38: ...j I I i i j I i j I i i j I i i j I i i i i r i 1 I j I i i i i i i i i i i i 1 6 ...

Page 39: ...Teletext printboard ___ _ _ _____ _ _ _ _ _ __ _ I r I I I I I I I I I 1 I I _ ...

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