Kurzweil SP2X digital piano DSP issues and flash Eeprom recovery

Thread Starter

alfrfedoalejandro

Joined Sep 29, 2023
2
Hi Folks, here with a question about firmware recovery. I have a strange issue with a Kurzweil SP2X digital piano. The main question is how to connect a TL866 programmer to flash the mainboard soldered TSOP48 Eeprom chip using the 50 pins connect_boot on schematics.



The equipment is a dead non working unit that came years ago for repair from other service center. Unfortunately the DSP unit is partially damaged with random issues caused by the extreme working temperature of the ASIC sound DSP array. At the beginning the main problem was a faulty capacitor that entered in short circuit fusing a protection +Vcc resistor on the display and switches panel board. I replaced that and the unit started to turn on again supposedly without issues. I also checked voltage regulators replacing the 7805 and 7812 on the MIDI and 88 keys Fatar scanner board with new ones and tested the 3,3V and 2,5 and 1,8 volts SMD regulator on the main board, everything was fine. But after 1 hour of usage the sound started to distort with a white noise like a FM weak radio station. Sometimes the noise affected only the left channel, then the right channel or both in an randomly way. I suspected first a clock frequency drift on main Xtal 24,576 Mhz but with the oscilloscope the frequency is 100% accurate without drift issues, also checked the 12,288 Mhz Kurzweil MARA proprietary DSP clock out. Also checked the 6 Mhz secondary Xtal for the USB and 4Mhz clock fot the MIDI RS232 serial to parallel transceiver. Because everything was fine I suspected data corruption in the mask ROM chip were samples are stored or issues on the DRAM for the effects unit. With the heat station I reflow the DSP chip and figured out that heating the mask ROM or DSP the white noise disappears for moments and came back. But the strange of all was that lowering the 3,3 volts for the DSP chip to 2,15 volt the noise goes of totally. The sweet spot was around 2,3 volts and 2,8 volts for the DSP unit. It seems that the high temperature of the MARA DSP chip approx. at 80 grad Celsius over the years of usage affected the ASIC core on the I/O bus. Lowering the DSP voltage requires less I/O current on the data and address bus so the point here is that the high temperature operation on MARA DSP chip wear out the ASIC core after 5 years of usage.



The MARA DSP chip is the big one, on the corner right side are the 3,3 and 1,8 volts regulators. I have in my room another SP2X that I buy used in 2013 replacing the potentiometers on the pitch and modulation wheels. Also I have soldered heatsinks on the 3,3 V and 1,8 regulators installing also a PC mainboard southbridge heatsink on the DSP MARA chip because the DSP working operation of 70 grads Celsius is unacceptable. No issues after 15 years of usage thanks to the heatsink lowering DSP operating temperature at 35 grads because I was aware that a DSP will not survive for many years working at 70 Celsius on plastic case cover, inside the ASIC core the hot spot runs higher at 100 Celsius or more. There are a lot of videos on youtube about the failures on dead Kurzweil's affecting the SP4, SP5, PC3Le because use the same DSP architecture running to hot.

The main question is if I can connect a TL866 programmer on connect_boot 50 pins to flash the AM29F160 Eeprom without unsoldering the chip from the mainboard. Why, because the only way to have the firmware binary file seems to be reading from my former 2013 SP2X the flash Eeprom data. But first I will check if the TL866 works properly in the dead mainboard detecting the AMD29F160 device. The corrupted firmware seems to run something because are active signals on data and address bus, but the communication to the panel display board is missing. And the proprietary Kurzweil way to update the firmware is through a MIDI file playback a file not in binary format at all. Because MIDI files are also binaries I expected that renaming to .bin would suffice but on Hex editor the format is Kurzweil proprietary. Here the link about the firmware files https://kurzweil.com/wp-content/uploads/2019/10/SP2X_COMBV110.zip if someone want to investigate, there are two MIDI files and how-to tutorial. I would be nice if the data can be extracted from the MIDI files, also the another question is where the bootloader information is stored, inside the AM29F160 chip?. In the TL866 application there is no way to select the bootloader Eeprom zone.


I include the information from datasheet about the signals for the flash Eeprom programming



And the 2 Midi firmware files top sections the bootloader to start up the system and the main code





Any ideas on how to proceed using the boot connect port the 50 pin connector on left side same as a SCSI hard drive cable and if is possible to extract the Eeprom data in binary format from the zip MIDI files? Tanks a lot for any suggestions.
 

dl324

Joined Mar 30, 2015
16,715
first I will check if the TL866 works properly in the dead mainboard detecting the AMD29F160 device.
It sounds like you have the equipment to remove and replace the device. Is there a reason why you don't want to do that?

If the board wasn't designed for in-circuit programming, connecting the programmer to the FLASH (it's not EEPROM, that's a different technology), the programmer will power up the rest of the circuitry on the board and it will fight you for control of the FLASH device.
 

Thread Starter

alfrfedoalejandro

Joined Sep 29, 2023
2
It sounds like you have the equipment to remove and replace the device. Is there a reason why you don't want to do that?

If the board wasn't designed for in-circuit programming, connecting the programmer to the FLASH (it's not EEPROM, that's a different technology), the programmer will power up the rest of the circuitry on the board and it will fight you for control of the FLASH device.
There is a way programming the EEPROM flash chip without unsoldering. The removal of J2 jumper on schematics disables the access of the EEPROM flash memory from CPU to enable an external programmer connected on 50 pins connect_boot. The problem with Kurzweil is the lack of support and the poor quality of the digital chips, starting with the MARA DSP proprietary sound chip. And the other problem that is a nightmare is the way of firmware programming the device with a MIDI file. The .bin file is not available to download making things more complicated.

Here a video I was able to boot the system again reducing the Vcore 3,3 volts to force a reset but the DSP sound chip seems to fail a lot. Such noise issues affects the entire line of Kurzweil synths including the flagship PC3X the most expensive of all.

Kurzweil MARA DSP failure white noise issue

Thanks in advance for the suggestions. The reason why I don,t want to remove the EEPROM is because I don,t have the direct .bin file to program the chip. Also the PCB quality is very poor and the risks to have broken cooper traces on the unsoldering and soldering process is very high.
 

jawwadh19

Joined Dec 22, 2023
1
Hi,
I have the same issue with my SP2X. I get white noise and the screen shows just dots, no error code. I retired my Piano and shifted to CLP735. But after reading alfrfedoalejandro post, I got hope that I can fix the problem. I live in an area where there is no Kurzweil support available and I have to do all by my self. I am a electronics design and can work on repairs.
 
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