LG Electronics TL-AT130M Servo Circuit, Video is unstable in PB mode, Drum motor stops

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SECTION3 ELECTRICAL

ELECTRICAL TROUBLESHOOTING GUIDE

2.SERVO CIRCUIT

(1)Video is unstable in PB mode

In PB mode

Does noise level on the screen

change periodically?

YES

Does CTL pulse appear at

NO

IC501 Pin 76?

YES

NO

Does CTL pulse move on tracking?

YES

Does Video Envelope wave form NO appear at IC501 pin 86?

YES

Replace IC501.

Is adjusting height of CTL

head accurate?

Replace IC501.

Check the Pre-Amp circuit

NO

Readjust the height

of CTL fead.

(2) Drum motor stops

When the drum moter stop

NO

Is there 12V at PMC01 Pin8?

YES

Check Power circuit

Is there 2.8V at PMC01 Pin12?

YES

Check the Ass’s between

connector(PMC01) and Drum motor

NO

Does Drum PWM pulse	NO
Does Drum PWM pulse
appear at IC501 Pin34?

YESYES

Aren’t pattern or componets between

IC501 Pin34 and PMC01 Pin12 short?

Does DFG pulse appear at

NO

IC501 Pin65?

YES

Does DFG pulse appear at

PMC01 Pin3?

NO

Check the Ass’y between

junction PCB and Drum motor

Aren’t pattern or componets between

IC501 Pin34 and PMC12 Pin1 short?

Does Drum PWM pulse appear	NO		Replace IC501
at IC501 Pin34?

YES

Aren’t pattern or componets between

IC501 Pin34 and PMC01 Pin12 short?

3-4

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Contents KEY Table of Contents Summary Front RearIndicator Panel VCR Function IndicationTerminal Signal Levels IN/OUT DescriptionSummary Critical Parts Replacing Time Table Cabinet & Main Frame Exploded Views Cabinet & Main Frame Section Parts list Cabinet and Main Frame SectionPacking Accessory Section Parts list Packing & Accessory SectionPG Adjustment Connection chart of PG adjustmentPower CircuitSMPS No 5.3 a No 24No 5.2 a to AVCP, Bias When the drum moter stop Video is unstable in PB modePB mode Servo CircuitWhen the capstan motor stops Capstan motor stopsC Circuit No Video in EE ModeNo Video in EE Mode Clean the Drum Check the System Circuit IC501 Pin Pin 16, 40, 55, 58, 87?Is the EE signal normal? Is 5V applied to the IC301 Pin 16, 40, 55, 58, 87?No sound in PB Mode No sound in EE Mode No sound in PB ModeNo sound in EE Mode Audio CircuitNo sound in REC Mode No sound in REC ModeAuto Stop SYSTEM/KEY Circuit Auto StopNo cassette tape loading No OSD display No Key displayOSD Circuit No F.OSD displayElectrical Block & Circuit Diagrams Power Block Diagram Power Clrcuit Diagram Audio Block Diagram C Block Diagram V Circuit Diagram Electrical Block & Circuit Diagrams System Block Diagram Electrical Block & Circuit Diagrams System Clrcuit Diagram Jack Clrcuit Diagram KEY-BOARDCLRCUIT Diagram Electrical Printed Circuit Diagrams KEY 1 P.C.BOARD KEY 2 P.C.BOARD Jack P.C.BOARDMechanism Top View Bottom View Part Fixing TypeDrum Assembly Fig. A-1-1 Drum MotorPlate Top Fig. A-2-1 Fig. A-2-4Bracket Assembly L/D Motor Fig. A-2-4 Gear Assembly Rack F/L Fig. A-2-5Holder Assembly CST Fig.A-2-2 Arm Assembly F/L Fig. A-2-6Base Assembly A/C Head Arm AssemblyCleaner Head F/E Fig. A-3-2Arm Assembly Tension Fig. A-4-3 Brake Assembly T Fig. A-4-1Brake Assembly RS Fig. A-4-2 Reel S / Reel T Fig. A-4-4Lever T/up Fig. A-5-4 Arm T/up Fig. A-5-5 Arm Assembly Pinch Fig. A-5-3Opener Lid Fig. A-5-2 Brake Assembly Capstan Lever F/R Fig. A-6-3Lever Spring Fig. A-7-6 Gear Sector Fig. A-7-3Lever Tension Fig. A-7-5 Just lift the Plate Slider upGear Assembly P2 Fig. A-8-1/ Gear Assembly P3 Fig. A-8-2 Base Assembly P2 Fig. A-8-3/ Base Assembly P3 Fig. A-8-4Base Tension Fig. A-9-2 Base Loading Fig. A-9-1 Arm Assembly Idler Fig. A-9-3Arm Assembly Idler Base Tension Base LoadingDeck Mechanism Adjustment Mechanism Alignment Position Check Fig. C-1Mechanism Condition Checking TorqueTest Equipment/ Fixture Test Conditions Torque Gauge 600g.cm ATG Cassette Torque Meter SRK-VHT-303Guide Roller Height Adjustment Head Assembly Audio/Control A/C Head AdjustmentAdjustment Procedure/Diagrams Head BaseAdjustment Procedure Adjustment Diagram Value AdjustmentPrecise Adjustment Azimuth adjustment 1KHZ 7KHZAdjustment after Replacing Drum Assembly Video Heads Check the Tape Travel after Reassembling Deck AssemblyCheck before starting repairs Maintenance Procedure Required MaintenanceScheduled Maintenance CleaningGear Sector Gear Cam Base Loading Gear Drive GreasingChassis Bottom Chassis Top Base, Tension Lever, F/R, Base, TensionGear AY, P2 & P3 Mechanism Troubleshooting Guide Auto Stop PLAY/CUE/REV Nono Is the Belt ok?Front Loading Mechanism Cassette does not load Exploded Views Moving Mechanism A11 Parts Section NSP Not Service PartRUN Date LOCA.NO Description Specification Remarks Description SpecificationAssembly Section Remarks ScrewBuzzer LOCA.NO Description Specification Remark BATTERY,LITHIUMElectrecal section CapacitorLOCA.NO Description Specification Remark NP0 TS Coil DiodeFuse DigitronFilter HolderR121 0RD1800F608 R3G6 0RD1800F608 R553 0RD2200F608 R610 0RD2701F608 Switch LOCA.NO Description SpecificationRemote Controller Receiver Remark RESISTOR,DRAWINGTAL TransformerVaristor Zener Diode