Format: MS WORD | Chapter: 1-5 | Pages: 65-80 | .
FIRST EDITION OF THE TAPE RECORDER SERVICING MANUAL
ABSTRACT
The essential instrument for any workshop are now and flutter meter electronic mill voltmeter audio Osillator distortion test set: NAB1 D/N and CCIR weighting filers IKH2 band pass filter tension Jauges (with scale ranging from milligram to kilogram) Torgue Gauges B.A and metric open and box spanners a wide variety of test and connecting leads toad resistors and parallel boxes.
CHAPTER ONE
INTRODUCTION
Sales of cassette recorder now account for a large share of the audio marteet and because of the enormous growth of interest in this system rather wore cutleries have been devoted to cassette than to reel-to-reel machines. As far as servicing is concerned the principles are the same for classtee as for reel-to-reel recorder but a degree of ingenuity is frequently required when making mechanical adjustment on some of the chapter models for instance torque clutch and brafee adjustments are often made on a trial error basis by bending a lug with a pair of pliers until the required result is obtained.
For the entries in this manual I we have assumed that we are writing for a technician who is already conversant with electronic fault finding techniques and has some experience of servicing tape recorder however for those new to this aspect of servicing the notes in the remainder of this introduction may be of some value. The circuit failed about are supposed to be fenown circuit that have been studied in general from life power supply circuit amplifier circuit oscillator modulator and demodulator circuit digital circuit life clock generators counters shift register discoverer multiplexes Rome RAMS etc are supposed to be familiar to the student from many year of study.
SECTIONS OF PROJECT
A project lifee an Essag has sections or parts these can be identified as:
a. Concept
b. Specification
c. Block diagram
d. Circuit design
e. Circuit diagram
f. Component sourcing
g. Prototyping
h. Construction or assembly
i. Testing
j. Packaging
a. Concept
1. A project starts with a concept born out of thought or idea of a need e.g to produce a dual voltage (+) power supply to supply circuits that use op amps that require positive and negative voltages to produce inter court EE department for school of engineering usually many ideals will cross ones mind the ability to put any into use depends on ones knowledge base will dictate the design steps.
b. Specification
Will be made after testing has are specification of certain system as example of what we are taking about A.C power transformer
a. Supply voltage = 220y
b. Output voltage = 26y
c. Current output = 2a
c. Block oragram
This is the diagrammatic representation of the sections that maker up the system with rectangular labeled boxes. The designer thinks of various section that should be put together to produce the desired result and draw them. These boxes are linteed with arrowed lines to show how signal moves from one box or block to another. The input to any block is on the left and the output on the right more than one block diagrams could be put together for a system each considered critically before one is finally accepted.
OVAL VOLTAGE POWER SUPPLY UNIT
AC
Output
D.C to A.C CONVERTER
d. Circuit design
For design the first step is to look for a circuit that can perform the task the next step is to calculate the values of the component that will be used determine their power and voltage rating use will be made of the theories covered in the studies.
Specification
Following the concept closely is the specification to the project it one tartees cloth to a tailor and say sew we a dress with this cloth what will the tailor do? To cut the strong short he will like to have the specification viz. Type of dress (shirt trouser short etc) other specs (hand length leg length waist chest neck etc).
These particulars (specifications) are necessary to produce a suiting dress in a similar manner electronic system requires specification before they are designed and produce. The specification states the goals operational conditions and limitations some specification are determined by environment and existing circumstances and not determined by producer of system. If a system is to be used in car the PSU will be the car battery and so the voltage is IZU if an O/P should go to a loud speaker the O/P impendence of the system will lie in the range of 4 to 16 Olus which are the impedances of a loud speaker.
One is constrained to use these factor of the specification when one is building for prompt area where NEAP does not exists the Psu specification must be de and must be used no other choice such issues as operating voltage. Frequency of use application range mechanical dimensions any data relating to its usage should be specified. these specification.
WHAT IS A PROJECT
A project they say was supposed to be the application of the theories learnt over the year to produce (design and construct) an operating system. A system is a circuit that performs a given on known taste such taste is supposed to be relevant to the society especially your society. It is therefore necessary to look around and discover societal need then produce a system to solve that need project in our contest can take a number of options.
1. Duplicate an existing system such that it can be said to be locally made this will use the existing circuit as copied in the existing product.
2. Produce an existing system that has been found to be very useful a different circuit that is found execute the fast. The circuit used way be coped or designed from scratch.
3. Discover a need that has no system to solve and then look for a circuit that produce the system to meet the need.
4. Interconnect existing system forming source to produce entering new system to execute a need.