AUDIO SWEEPER 7116C

7116C provides pure sine wave with very low total harmonic distortion. (approx. 0.1% THD ).  The total harmonic distortion of 7116C consists of 2nd Harmonic  component only and nearly without higher order harmonic components.  So,  7116C  is very  suitable  to test the sound quality ( spurious noise inspection ) of all kinds of loudspeaker, headphone, receivers,  piezo,  speakers  system…etc.

AUDIO SWEEPER 7116C MANUAL:

        Model-7116C（Audio sweeper ）

The  frequency produced by 7116C is more  stable  than  the  ordinary  beat  frequency oscillator produced.  and  the sine  wave  provided  by 7116C  is  purer  than  the ordinary function generator.  Therefore,  7116C has both advantages of low distortion and high stability.  do  not use the  ordinary  function  generator  to  test  the  spurious  noise  ( rattle and  buzz ) of loudspeaker, loudspeaker, receiver,  etc.…  Because  user  will  easily  neglect the  prohibited  spurious  noise  caused  originally  from the high order  distortion  component of the function generator.

1. Automatic Sweep Generator :

Depress Auto / Manu (8) push button, Then 7116C will sweep forth and back between

the frequencies set by start adjustment knobs and stop knob.

2. Manual Sweep Generator :

Depress start (3) or stop (4) push button, adjust Start / Stop coarse knob.

3. A Constant Frequency Generator :

Depress start (3) or stop (4) pushbutton, And adjust start Coarse / Fine knob (5) / (6)

or stop knob (7) to the frequency desired.

Ⅰ. Power Portion

In case after power on, indicator of Model – 7116C did not light up, no digits

displayed on two Liquid Crystal Displays ( LCD ), and no single function occurred, then,

users are required to check the fuse at the rear panel of 7116C, if fuse was burnt

out, replace a new fuse with the same spec., if fuse is O.K., users may undergo

primary trouble shooting by following the procedures of below- mentioned, to detect

which PCB is faulted, or users may contact either Sunlight’s agent or directly with

Sunlight, to discuss on the matter of how to repair the faulted Model – 7116C.

Remarks :

Burnt out of fuse is usually caused in following circumstances :

A. Internal circuit severely damaged, faulted 7116C should send back to Sunlight for repair.

B. Misconnection of power to higher line voltage, causing the permanent damage of an internal metal oxide varistor, in this case, it is in vain to replace only a new fuse, instead, users should replace first a new metal oxide varistor, then, replace a new fuse, otherwise, the replaced fuse will still be burnt out again. If usershave no 〝 Metal Oxide varistor Ⅱ on hand, they may cut off the metal oxidevaristor, but without the varistor, when misconnection of power occurred, the circuit of Model – 7116C will no longer be protected. ( Metal Oxide Varistor is round in shape, & is about 1 cm. in diameter, it is fixed on the position as below Fig. shown. For 220V and 110 power voltage, a metal oxide varistor with code no.: of 〝 471K Ⅱ & 〝 221K Ⅱ are being used respectively

The lowest resonant frequency of a midrange or a tweeter is a very important parameter when designing the speaker system. And the lowest resonant frequency of a woofer would affect the regeneration of low frequency greatly. Therefore, It’s necessary to measure the Fo value of each kinds of loudspeaker. And 7116C can measure the Fo value manually.

1. Connect the loudspeaker to the output terminal of 7116C.
2. depress the Fo pushbutton (2).
3. Adjust the output voltage to approximately 0.5V.
4. Adjust the start Coarse / Fine knob, To start at 20Hz up to a higher frequency slowly. ( Especially slowly for the woofer ) The voltage value will increase as the frequency increasing. A maximum voltage should be reached at a certain frequency, And the voltage value will fall down when the frequency goes higher again. Please turn the start Coarse / Fine knob back to the frequency at the highest voltage, And the frequency is the lowest resonant frequency of the loudspeaker at that voltage.

5. In EIA standard, It is recommended to test the Fo value with 1.0V ± 10% voltage across the terminals of the loudspeaker. So user should adjust the voltage volume to 1.0V after the Fo value was found. Then repeat steps 1. to 4, To make sure that the lowest resonant frequency found is exactly at the highest voltage of 1.0V± 10%.

Note :

It would obtain the different Fo values at the different voltages. and most countries has their own definition for measuring the Fo value. For example: Taiwan and Japan do not apply 1.0V to test the Fo value. Therefore, It is necessary to define the measuring condition when providing the specification of the Fo value.

6. However, This measuring speed for researching the Fo value is too slow in production line. Using the〝 Digital High Speed Fo Meter Model – 7117K Ⅱ would be the most adequate instrument in the production line for undergoing 100% inspection

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