XL-55 (serv.man22) - Sharp Audio Service Manual (repair manual). Page 12

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1. Outline of tuner (radio) test mode
    The tuner test mode is intended to store the adjustment and measurement frequencies in the preset memory CH without

frequency setting by adjusting personnel when the tuner section is adjusted in the production line.

2. Details of tuner test mode
     When the power is turned on by using the ON/STAND-BY button while the BASS/TREBLE and REW/REV buttons are held

down in POWER OFF state, the frequency for adjustment and measurement of destination specified by the AREA terminal
is preset and stored in the preset memory CH. However, Ordinary 1 and Ordinary 2 are set to the designation (destination
selected by SPAN switching operation) set when the test mode is obtained.(Memory/Set+Function Key Span Charged) (As
for frequencies to be preset and stored for each destination, refer to item 3.)

    The tuner test mode is started from preset No.1.
    The operations of test mode are identical with the ordinary operations of TUNER function. However, FUNCTION switching

is invalid.

     Since it is necessary to discard the content of preset memory when the tuner test mode is ended, "0000" or "1111" bits are

written in the memory to be checked in case of memory check (in case of initial setting) so that memory abnormality is detected
in case of initial setting so as to ensure memory initialization.

When the tuner test mode is turned on, the following indication lights for one second.

• The TUNER TEST2 mode is set as a result of BASS/TREBLE+ REW/REV. -> POWER OFF -> IF AC is set to OFF in the TEST2

       mode, the initial state is restored.

When POWER is set to OFF, the memory of TEST2 mode is protected.
When the power is turned on again, the ordinary operation is enabled while the data is stored in the
memory (besides TUNER).

If AC OFF state is maintained in this state for about 1/2 day, start is executed in the initial state.

• To clear the whole memory, insert the AC cord, holding down MEMORY + STOP.

When the following operation buttons are pressed in this sate, the operation is executed as follows.

"ON/STAND-BY" ...... The test mode is turned off, the power is turned off, and the ordinary standby mode is set.
"FF/FWD" ................. The pickup slides toward the outer periphery while this button is held down.
"REW/REV" .............. The pickup slides toward the inner periphery while this button is held down. However, if PU-IN is on, input

is invalid.

"PLAY" ..................... Invalid
"STOP" ..................... Return to step 1

*If the focus is disturbed, the process returns to step 1.

Other cautions
• TOC IL is not executed in the test mode.
• As for button operations other than those shown above, only the sound volume operation (with JOG) is accepted.

The CD initialization operation flow is executed to the end, the mute is set to off, and playback is started. Even when the
playback reaches the outermost periphery of disc, the operation does not stop. The LCD display indicates the playback past
time as in case of ordinary CD playback.