Technics SX-PX552, Руководство по обслуживанию

Страница: 16 / 87

No. PCB TEST MODE Procedure
6 MKB Keyboard ROM (IC1)
check Press and hold the two A keys shown below, and then turn
power switch.
If the keyboard ROM (IC1) is OK, the TOUCH SENSITIVITY LIGHT LED only flashes on
control panel.
If it is defective, the LEDs (LIGHT and NORMAL, or LIGHT, NORMAL and HEAVY) flash.
Connection between serving CHECKING DEVICE and MAIN P.C.B.
12. MIDI Implementation chart
13. PRECAUTIONS BEFORE SERVICING
13.1. Precautions for measuring of the output waveforms
1. The waveform was measured with a “National Digital Storage
Oscilloscope VP-5730A”. Therefore the waveforms of musical
tone signals shown may differ somewhat due to the difference in
the timing of triggering.
2. Since the 1/10 test probe is used, the indicated voltage value on
the bottom part of each waveform illustration is 1/10 of the actual
value (e.g. 0.2 V/cm should be 2.0 V/cm).
3. To measure the waveforms, first set this unit to the service
diagnostic mode (refer to “WAVE ROM test”). The WAVE ROM
output will then be output as a sine wave to facilitate the servicing
check.
16