IDENTIFYING THE FAULTY STAGE,Audio & video system
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This document discusses identifying faulty stages in audio and video systems. It describes four types of circuit configurations: sequential, divergent, convergent, and closed loop circuits. For sequential circuits, common methods for identifying the faulty stage include signal injection and tracing, signal substitution, and short circuiting inputs. The split half method can also help locate the faulty stage. Divergent circuits have one input and multiple outputs, while convergent circuits have multiple inputs and one output. Fault diagnosis techniques include isolating inputs. Once the faulty stage is identified, measuring component values and substituting components can identify the faulty component. Common component and PCB faults are also outlined.
IDENTIFYING THE FAULTY STAGE,Audio & video system
- 1. AUDIO & VIDEO System IDENTIFYING THE FAULTY STAGE Presented by: PRANAV VEERANI (130280111117) Submitted to : PROFESSOR PRATIK GIRI GOSWAMI
- 2. IDENTIFYING THE FAULTY STAGE Stages are connected in four types of circuit configurations: 1.Sequential stages 2.Divergent circuits 3.Convergent circuits 4.Closed loop(feedback) circuits
- 3. SEQUENTIAL STAGES There are three method of this stage . Stages are in series one after the other. 1.Signal Injection & Tracing 2.Signal substitution 3.Short circuiting the input
- 4. SEQUENTIAL STAGES 1.Signal injection & tracing : In this method signal is injected at the input of the system & its presence is detected by signal tracer at different stages. Signal tracing can be done by a diode tracer, or a cathode ray oscilloscope(CRO). 2.Signal substitution : In this method , Signal is given at the inputs of different stages & the final output is checked. 3.Short circuiting the inputs : One by one for locating the source of noise(like self oscillations).
- 5. SEQUENTIAL STAGES In sequential circuit , the quickest method of finding out which stage is faulty is split half method . Split Half Method : In this method , the output at a stage in the middle of the sequential stages is checked. If it is correct, the first half of the stages is alright & the defect lies in the second half. Then, the output at the middle stage of the second half is checked to find out which portion is defective & so on ,until we reach at the correct stage . Figure of this method is shown below:
- 6. SEQUENTIAL STAGES Split Half Method
- 7. DIVERGENT CIRCUITS The circuit which has one input path , but the output takes several paths is called divergent circuit. One such circuit of power supply output , which sends power to several stages from its output point.( )
- 8. DIVERGENT CIRCUITS Several loudspeakers connected to one output of final power amplifier stage.(1) Switching circuit with one input and several output.(2) DE multiplexer circuit which receives one input but gives several outputs.(3) Video detector input is one but there are several outputs, like sound section, luminance , chroma and raster sections.(4)
- 10. CONVERGENT CIRCUITS The circuit which has several input but only one output is called convergent circuit. Mixer stage for microphone in the PA system in which several microphone are connected in the input and there is only one output for feeding to the amplifier(1) 1
- 11. CONVERGENT CIRCUITS • Multiplexer which takes several signals in its input and gives out only one signal.(2) • Logic gates(except NOT gate) which give one output for two or more input.(3) • Switching circuit with several inputs and one output.(4) 2 3 4
- 12. CONVERGENT CIRCUITS Fault diagnosis in convergent circuits will also be done in the same way as in divergent circuits . Each input circuit will be isolated to find the output . If expected output is obtained after isolating a circuit in the input, than that circuit is faulty.
- 13. CLOSED LOOPCIRCUITS Feedback circuits from a closed loop. Negative feedback(1) Servo controlled devices(2) Positive feedback(3) Automatic gain control(4)
- 15. FAULTY COMPONENT • Faulty component in the Faulty Stage: 1.Measurement of resistance, dc voltage and ac signal voltage at the specified test points. 2.Substitution of the suspected component by a good one. Passive and active components may become open or leaky or short. The causes for components to become faulty are many . But voltage fluctuation, transients , dust , temperature variation , grease between tracks of PCB, dry or cold solder joints, vibrations/shocks, mishandling , expiry of life ,etc. are the most common causes for failures. Dust is the biggest enemy of an electronic equipment because it prevents radiation of heat from the ICs and other components.
- 16. FAULTY COMPONENT Some common faults: Resistor(open) Capacitor(open , short , leaky) Inductor(open , short) Transformer(leaky) Diode(open , short) Transistor(open , short , leaky)
- 17. FAULTY COMPONENT Common faults in PCB: 1.Solder bridge between adjacent tracks 2.Pin holes 3.Break in plated through hole(PTH) 4.Loose connection in connectors 5.Dry or cold solder joint
- 18. REFERENCE AUDIO AND VIDEO ENGINEERING SYSTEMS BY R G GUPTA
- 19. THANK YOU
Editor's Notes
- #7: Output at Ais checked.if alright, the stages from microphone to IV stage are correct.the output B is checked. If ,no output either the V or the VI stage may be defective. Then , output at C is checked which will finally decide whether the stage V is defective or the VI .
- #9: Trouble shooting in divergent circuits is done by isolation technique.