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RP700 REPAIR INSTRUCTIONS
This model doesn't provide an autotest procedure, then in case of electr. fault we suggest to proceed on its repairing as follows:
[1] Switch ON the Piano and check if the led on cabinet is lighted and the led of Grand Piano button is fl ashing after some seconds from the
switch ON phase.
[2] Then, after having opened the RP700 cabinet, check the presence of supply voltages on power board ass.y (+5V, +/-12V, and +/-20Vcc for
power amplifi ers TDA 7296].
[3] POWER ON/OFF, MASTER RESET, MUTE TIMING check
Using dual channel oscilloscope, try to visualise +5V Power Supply, VOK, Reset , Mute signals timing during RP700 POWER ON, as by timing 1;
Starting from the POWER ON event the RP700 remains in Reset condition until the +5V Supply rises 4.75V value on IC17 pin2 (MAX709)
setting the active VOK (after 200ms) and Reset controls; the VOK and Reset signal are connected to pin 209 and to pin 206 of DRAKE Chip
(IC9); the RST delay should be >60uS refer to VOK rise time . The Mute signal is controlled by RP700 O.S., after the fi nish of start-up phase,
it actives the analogue signals on IN/OUT's plugs and on speakers, through RL2 & RL1 relais of 731083 power supply board.
[4] MAIN (CPU) BOARD ASS.Y CHECK
The RP700 Digital Piano provides a main (CPU 761300) board ass.y that requires a specifi c knowledge of DRAKE (Dsp Risc Advanced Keyboard
Engine) custom chip, no easy to extend and to check outside of GM factory; so, we suggest the replacement of main board when the RP700
doesn't work at all or work partially on sounds generation and on keys & controls playng. In any case the following informations can be useful
to locate a specifi c problem on main board, before to replace it:
[4.a] MASTER & BIT CLOCK
The Master clock (MCLK) of main board is generated on DRAKE chip (pin 160-161) with XT1 quartz oscillator (fo =11.2896MHz)that you can
check by oscilloscope on pin 2 IC19 as by fi g. 1: The Bit Clock (BCLK) of main board is generated inside DRAKE chip (pin 230) dividing 4 times
the MCLK; its frequency is: =2.8224MHz that you can check by oscilloscope on pin 26 IC19 as by fi g. 2:
[4.b] CONTROLS PANEL BUS TIMING
It is generated by DRAKE chip (IC9) through the RP700 O.S.; the relative signals can be checked by oscilloscope as shown on timing 2.
[4.c] CPU-KEYBOARD INTERFACE TIMING
It is generated by DRAKE chip (IC9) through the RP700 O.S.; the relative signals can be checked by oscilloscope as shown on timing 3.
[4.d] DRAKE - DAC SERIAL BUS TIMING :
It is generated by DRAKE chip (IC9) through the RP700 O.S.; the relative signals for the D-Sigma stereo D/A converter can be checked by
oscilloscope as shown by timing 4.
[4.e] If the previous checks on main board are OK, the RP700 has to generate sounds; to verify this condition, press the SOUND DATA UP
& DOWN buttons at same time to active the DEMO function with the GRAND PIANO led fl ashing. Now a sound pattern sequence should be
played by CPU board, in line with the O.S. release installed; in absence of sound from speaker verify with oscilloscope the presence of the
audio signal on CN7 connector, pin 14, 16. At last try to reload the O.S. on Main board as by following instruction.
[5] OPERATING SYSTEM UPDATE
The O.S. of main board is preload into (IC2) NAND FLASH Memory from GM factory; the 256Kbit NAND FLASH Memory is formatted and
written with O.S. pattern using PC system with RS232 serial port and hardware interface kit.The update of O.S. must be taken out from
qualifi ed Personal; it requires the opening of RP700 cabinet, the shift of J1 Jumper from E2 to UART position on CPU board, and the proper
installation of an interface kit on main board CN1 connector; to execute this operation, please refer to the separate document O.S. update
installation instructions procedure.
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