Zenith IQB36B86R Manuel de service

HIGH VOLTAGE AND X-RADIATION PROTECTIONA potential source of x-rays is the picture tube, if the highvoltage (HV) is out of specification. When the HV

CA-6CA CIRCUIT DESCRIPTIONSFor those CA chassis that have the keyboard and IR detector built onto the module, the schematics areincluded. Keep in min

CA-7Microprocessor Controltypes of on-screen display (OSD). Neither sync pulses come directly from the video processor where theyare first produced.

CA-8CA CIRCUIT DESCRIPTIONSMemoryThe EEPROM, IC6001, is a small but vital part of the CA receiver. This 512 byte memory chip is respon-sible for stor

CA-9IF ReceiverTunerCable or off-air signals are received into the television by way of the antenna jack of the tuner, TU6000.The input and output imp

CA-10CA CIRCUIT DESCRIPTIONS<<Figure CA-9>>ICX2200 powers its IF section using +9VPIF (pin 9) and +9VSIF (pin 48). The ICs main VCC is a

CA-11Video ProcessingIntroductionICX2200 has numerous duties involved in television image and sound production. As mentioned above, itprocesses sound

CA-12CA CIRCUIT DESCRIPTIONSswitching channel of this IC switches the PiP between external and internal video sources based on the PiPSwitch1 signal (

CA-13Video ProcessingRGB output, this circuit helps to prevent blooming. Excessive current draw in the picture tube will lowervoltage and hence decre

CA-14CA CIRCUIT DESCRIPTIONSthe PIPB1 connector provide sync to the PiP processor. Pins 9 and 10 of the same connector allow I2Cbus communication bet

CA-15Video Processingpowered by the +215V source derived from the sweep transformer, but the actual DC voltage at thecollectors will be lower (+130 vo

CA-iiiPrefaceThis manual has been designed as a supplement to the CM-151 CA/CB training manual (923-3351TRM).It provides circuit descriptions as well

CA-16CA CIRCUIT DESCRIPTIONSDeflection ProcessingThe last portion of the video processor to be discussed is the deflection section. This is the part

CA-17Deflection ControlIntroductionAfter deflection control signals are produced by ICX2200, they need to be modified and amplified beforethey are out

CA-18CA CIRCUIT DESCRIPTIONSA number of secondary voltages are also provided by the sweep transformers action. Particularly, +215volts is supplied f

CA-19Deflection Controlvoltage. The HV shutdown circuit utilizes a rectified DC voltage across CX3003. This voltage is applied toa zener diode, ZDX3

CA-20CA CIRCUIT DESCRIPTIONSresulting waveform for yoke current is a sawtooth with rounded peaks.Vertical AmplificationMost of the vertical signal amp

CA-21Deflection ControlCRT ProtectionCRT protection is provided for the CA in circuitry off the vertical amplifier. In case of a damaged IC2100or a s

CA-22CA CIRCUIT DESCRIPTIONSAudio AmplificationThere are three audio circuit configurations used in the various CA chassis: mono, stereo, or MTS (Mul

CA-23Audio DevelopmentIn the mono circuit, composite audio is fed directly from pin 2 of ICX2200 into the audio amplifier circuit.However, on stereo a

CA-24CA CIRCUIT DESCRIPTIONS<<Figure CA-23>>IC1402 is powered by the +18AUD at pin 4. Pins 5 and 8 receive the audio input, while the out

CA-25Audio Development123456789101112131415161718192021222324253626272829303132333435373839404142434445464748BASSL2TRE-RTRE-LSURRINSURROUTLSOUT-RLSOUT

CA-ivTable of ContentsSection 1General Safety Guidelines ... CA-iCA Ch

CA-26CA CIRCUIT DESCRIPTIONSExternal Audio OutputThe output pins here also feed the variable audio output circuitry. This common emitter amplifier ha

CA-27FlowchartsStart1. No PowerPlug receiverinto AC source.ReplaceFX3401.ReplaceFX3402.ReplaceTX3401.Replace ICX3400,QX3401, DX3406,DX3407, DX3408.Re

CA-28CA TROUBLESHOOTING2. ShutdownStartDoes the setpower up formore than 2seconds?Does the DClevel at pin 29,ICX2200 riseabove 3.5 volts?Checkmicropr

CA-29Flowcharts3. No TuningStartAre all tunervoltagespresent? (Referto schematics.)Check tunerpower supplies.Is IF present atpin 11, TU6000?Does cha

CA-30CA TROUBLESHOOTING4. No VideoStartIs raster presenton the screen?Is 1.07 kVp-psignal present oncollector of HOT?Is regulated B+present acrossCX34

CA-31FlowchartsCheck audiopower supply.Is +18AUDvoltage presenton pin 9, IC804?StartDoes Q800 testOK?Does DC levelchange at pin 14,IC6000, whenspeaker

Section 2:CB Chassis

CB Chassis Safety GuidelinesX-RADIATIONTo prevent possible exposure to radiation caused by excessive CRTAnode voltage, the CB Chassis incorporates a 

CB-1Power SupplyIntroductionThe CB chassis is a cold chassis designed to support 27, 32, and 36 receivers. Its power supplyfeatures a controlled t

CB-2CB CIRCUIT DESCRIPTIONSbriefly drop. However, as the regulator begins to operate, it drives the chopper, and power derived frompin 13 of the tran

CB-3Power Supplycurrent ramp is input into pin 1 of ICX3412. This signal is then used to determine how regulation shalloccur as described below. OCP

CB-4CB CIRCUIT DESCRIPTIONSThe B+ provides power for deflection via the horizontal output transistor (HOT), QX3204, and for thetertiary voltages that

CB-5Microprocessor ControlIntroductionThe CB chassis employs IC6000 as its microcontroller. All end user and servicer controls are accessedusing this

CB-6CB CIRCUIT DESCRIPTIONSsor from pin 49 along with the processed RGB. An exception to this occurs when Gemstar® is displayed.Under that circumstan

CB-7Microprocessor Controlthe corresponding tuner to allow for clearer channel reception. The ideal voltage level here should bebetween +2.25 and +2.

CB-8CB CIRCUIT DESCRIPTIONSsignals entering IC2200 at pins 4 and 2 respectively and component video entering at pins 37 through 39.Note here that comp

CB-9IF ReceiverIntroductionThe CB chassis utilizes two tuners in order to provide PiP without requiring a second external source. Thisis with the pro

CA-1Power SupplyIntroductionThe CA chassis is a cold ground chassis deriving its power from a switch-mode, flyback type, powersupply. It features ind

CB-10CB CIRCUIT DESCRIPTIONScomes from pin 11 of the tuner, is filtered, and is fed into pins 5 and 6 of the IFP. AGC (automatic gaincontrol) voltage

CB-11IF ReceiverThe remaining outputs of the IF processor are the AFC control to IC6000 from pin 14 and the IF videosignal which passes through the AV

CB-12CB CIRCUIT DESCRIPTIONSJack-PackThe CB chassis provides multiple means for connecting external sources that supply video and audio signal.These p

CB-13A/V SwitchingSuppose the user has composite video connected to the Video 1 input and S-Video connected to the S-Video 1 input. If the user selec

CB-14CB CIRCUIT DESCRIPTIONSComponent VideoComponent video is handled differently than the other jackpack inputs. The CB lacks conversion circuitryto

CB-15A/V SwitchingOn sets using the digital comb filter, CV is fed into an A/D converter at pin 5 of IC2400. This IC is pow-ered by the +5VTune at pi

CB-16CB CIRCUIT DESCRIPTIONSIntroductionThe CB chassis video features include two-tuner PiP, comb-filtered video, auto kine bias, half-tone video,and

CB-17Video Processinglimiter threshold (1.5 mA for 27, otherwise 1.6 mA), the corresponding voltage across C2204 triggers thelimiter circuitry intern

CB-18CB CIRCUIT DESCRIPTIONSBefore this processed video is pre-driven by transistors Q2205, 2206, and 2207, the video signal can bedimmed by the half-

CB-19Video ProcessingAKB signal is derived from the collectors of Q5124, 5144, and 5164. These are fed back to the AKBcircuit via pin 5 of the 5C2 co

CA-2CA CIRCUIT DESCRIPTIONS<<Figure CA-2>>Another winding from the chopper (pins 13 and 16) provides feedback to the regulation loop in IC

CB-20CB CIRCUIT DESCRIPTIONSC5101 causes the G1 to become more positive. Since G1 is otherwise considered ground for the CRT, thisaction reduces any

CB-21Video ProcessingD2205R2224MR2222MR2223MPROVC2241MC2214MPROVC2215MPROVShutdownDC Levelfrom QX3001FlybackPulseTo ShutdownPin 18, IC2200<<Figu

CB-22CB CIRCUIT DESCRIPTIONSIntroductionThe CB chassis was developed to support CRTs ranging from 27 to 36. Major component of the deflec-tion circ

CB-23Deflection Controlment voltage, which is fed into pin 1 of the 2F5 connector, and pin 8s ABL signal. For the filaments part,since this voltage

CB-24CB CIRCUIT DESCRIPTIONSHigh Voltage ShutdownThe x-ray protection (high voltage shutdown) circuit uses the current from pin 6. DX3002 and CX3003c

CB-25Deflection ControlBoth positive and negative vertical ramp signals are required for operation. IC2200 supplies these to pins 4and 5 of the amp a

CB-26CB CIRCUIT DESCRIPTIONSWidth and Geometry CorrectionEast/West pincushion correction is performed by circuitry built into 32 and 36 sets. The w

CB-27Audio DevelopmentAudio ProcessingThe CB chassis uses IC1400 to process audio. This IC features true MTS (Multi-channel TelevisionStereo) sound,

CB-28CB CIRCUIT DESCRIPTIONSAudio BoostThose sets that have the audio boost feature output audio signal on pins 43 and 44 to IC1401. This IC ispowere

CB-29Audio DevelopmentThe +22VSB is supplied to pin 10. Pins 4, 9, and 12 are grounds for the amp. Pins 5 and 2 input left andright (L/R) channel au

CA-3Power Supplyvoltage at the base of QX3401 will switch that transistor on, shunting the regulator ICs base drive toground. Such an action kills t

CB-30CB TROUBLESHOOTINGStart1. No PowerPlug receiverinto AC source.ReplaceFX3401.ReplaceFX3402.Check RX3423.Replace TX3401 ifnecessary.Check DX3406,DX

CB-31Flowcharts2. ShutdownStartDoes the setpower up formore than 2seconds?Does the Vp-plevel at pin 18,IC2200 staybelow 1.0 volts?Checkmicroprocessorc

CB-32CB TROUBLESHOOTING3. No TuningStartAre all tunervoltagespresent? (Referto schematics.)Check tunerpower supplies.Is IF present atpin 11, WT1200?

CB-33Flowcharts4. No VideoStartIs raster presenton the screen?Is 1.07 kVp-psignal present oncollector ofHOT?Is regulated B+present at pin 3of TX3204?

CB-34CB TROUBLESHOOTINGCheck audiopower supply.Is +22VSBpresent on pin10, IC804?StartDoes DC levelchange at pin 14,IC6000, whenspeaker cut-off istoggl

CA-4CA CIRCUIT DESCRIPTIONSICX3402 regulates from the +18 VSB to provide +5 VSB. The +5 VSB powers the microprocessor,IC6000, and the tuner, TU6000.

CA-5Microprocessor ControlIntroductionThe CA chassis employs IC6000 as its microcontroller. All end user and servicer controls are accessedusing this