Heathkit IT-12, Assembly Manual, Page: 23 / 30

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There is practically no limit to the variety of useful applications afforded by this feature of the signal tracer. It is suggested
that the service technician further investigate other test procedures where application of a DC voltage to a component in
conjunction with a high gain amplifier will permit observation of voltage action.
Panel Connections
For additional flexibility of operation, the signal tracer panel features
five binding posts. These binding posts differ slightly from the
conventional type, in the respect that it is possible to insert a banana
plug into the top of each jack. They will also accommodate alligator
clips, spade lugs and conventional hook-up wire. Test leads such as
used in the VTVM can be used interchangeably with this instrument
when required. The panel arrangement of the Signal Tracer will permit
the utilization of other shop equipment for test procedure. For an
example, a VTVM can be connected either from B+ to plate or from
plate to common ground terminal. The VTVM will of course be
switched to the AC position and the calibrated scale of the meter could
be read directly for precise measurements during alignment procedures
and gain calculation. The output trans-former secondary connections
should be utilized if the test requirements required the elimination of
the DC voltage present in the primary circuit. A reduction in gain
indication should be expected.
Test Speaker
In service work it is frequently necessary to remove the chassis of a radio or TV receiver to the repair shop in order to
properly complete repair work. In many instances the speaker is a separate piece of equipment, and in some cases it is
installed in a rather inaccessible cabinet location. With the Signal Tracer at your disposal, it is not necessary to remove the
speaker in view of the fact that the output transformer and speaker are available as test or substitution units. In the
majority of cases, the original receiver circuit requirements specify the use of a permanent magnet type speaker and
therefore, the substitution can be readily made. The advantage of this feature of the signal tracer is readily apparent when
consideration is given to the time and effort conserved by eliminating the necessity for speaker removal and reinstallation
on every service job. In addition, the possibility of damage to the speaker cone during the handling process is eliminated.
Audio System
Quite frequently the service technician will be called upon to service automatic record-changers or phono mechanism. Of
course this equipment is usually removed from the cabinet of the receiver and transported to the service shop. On making
mechanical repairs or adjustments on the changer mechanism, it is frequently desirable that the output of the phono
cartridge be checked and actual conditions of tone reproduction simulated. Here again, it is.a relatively simple matter to
connect the audio input of the Signal Tracer to the output cable of the record changer. The changer output as heard in the
speaker of the tracer will permit detection of any irregularity in mechanical operation, such as turn-table wow or thump,
or any objectional noise that could be transmitted through the phono cartridge and reproduced as an undesirable condition.
This same procedure could be used in checking microphones and musical instrument pickups, and here again the results
obtained are interpreted on the basis of comparison made with previous tests on similar equipment. The signal tracer can
be used in checking FM tuners or other equipment requiring the use of an audio system