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Lexicon MX200 error Ar 00

Hello,

I have Lexicon MX200 Effect Processor, and it has failed. At power on, Audition LED blinks, then I see 1.4 on the display, and after that I see switched texts "Ar" and "00". If I hold the User Program Knob and release it when "Pd" text is displayed, I'll see fast changed numbers 0, 1, 2, and number 2 stuck on the display.
I've googled, and I see that a few people also had faced the same problem (the same behaviour I can see by few messages below), but I've not found the solution.
Could you please give me advice on how I can repair my MX200?
I have great skills in electronic development and repair.
Power adapter is good and all of the secondaries voltages are present and they're clean: -15, +15, +5 and +3.3V.
Also, I've checked oscillation on the crystals, and I see interoperation on the Address and Data bus of MCU and SRAM.
I may replace any chips if that will need, or program the flash, I have all of the necessary equipment.
Could you please explain to me what that test code means and what I should check.

Many thanks in advance.

Comments

  • HARMAN_EEldeHARMAN_EElde Posts: 1,144

    @victorchaplinsky said:
    Hello,

    I have Lexicon MX200 Effect Processor, and it has failed. At power on, Audition LED blinks, then I see 1.4 on the display, and after that I see switched texts "Ar" and "00". If I hold the User Program Knob and release it when "Pd" text is displayed, I'll see fast changed numbers 0, 1, 2, and number 2 stuck on the display.
    I've googled, and I see that a few people also had faced the same problem (the same behaviour I can see by few messages below), but I've not found the solution.
    Could you please give me advice on how I can repair my MX200?
    I have great skills in electronic development and repair.
    Power adapter is good and all of the secondaries voltages are present and they're clean: -15, +15, +5 and +3.3V.
    Also, I've checked oscillation on the crystals, and I see interoperation on the Address and Data bus of MCU and SRAM.
    I may replace any chips if that will need, or program the flash, I have all of the necessary equipment.
    Could you please explain to me what that test code means and what I should check.

    Many thanks in advance.

    1) open traces at U8 or U16
    2) defective AVR (U8)
    3) defective CPU
    4) wrong software on the avr chip.

  • Hello HARMAN_EElde!

    Many thanks for the reply.

    I've checked both GPIO traces between U16 CPU and U8 (pin 9 U8 to pin 8 U16, pin 10 U8 to pin 15 U16) and UART (pins 30, 31 of U16 to pins 11, 13 U8) traces, they're good.
    Also I've read AVR software (I'm a bit surprised that there was no lock bits at the MCU). Here it is: https://drive.google.com/file/d/18-LjJdlJs0PHzLipSRJRvhd3p-DTPLst/view?usp=sharing
    Fuses are the following: E:01, H:DD, L:D7

    EEPROM contains only 0xFF in all cells.

    When LED stops blinking I see that the level on the pin 8 U16 drops from high to low, and I don't see any signals on other GPIO line that connects CPU and AVR, nor UART lines.

    Could you please give me another advise: should I replace AVR chip and flash it by old firmware or I need to reflash old chip by a new firmware?
    Of course, the easiest way is to reflash AVR, and I will be very pleasant if you share the firmware with me (of course, if that's possible), if the attached file contains broken firmware.

    Or does it mean that the CPU is defective?

    Many thanks in advance!

  • upd: I've replaced AVR and flashed with old firmware and fuses, the behaviour stayed the same.
    Also I've checked all traces from the AVR: i2c to TUSB/CPU, i2c and reset to the codesc (/reset stays low always), two GPIO lines from AVR to TUSB.

  • HARMAN_EEldeHARMAN_EElde Posts: 1,144

    I would assume the AVR is not the issue then. Probably CPU. I would check with out Parts Dept ([email protected]) and they can see if that is available and in stock.

  • Dear HARMAN_EElde,

    I suppose, that AVR firmware is broken.
    I've analyzed it a little.
    We easily can see that the space 0x500-0x53f is filled by 0xff, and this space is a part of initializaton function.
    https://drive.google.com/file/d/1Sy1F7J2Z7uxgkjzYsEkTYUAUml7BzCyx/view?usp=sharing
    https://drive.google.com/file/d/1rAwyAPr4prqD2O17rwcEKyDJwprti-Et/view?usp=sharing

    Is that possible to ask you share AVR firmware code with me?
    If not, I'll try to find another way :)

    Many thanks in advance.

  • HARMAN_EEldeHARMAN_EElde Posts: 1,144

    We do not have the AVR Firmware code or files to send unfortunately.

  • Hi HARMAN_EElde,

    I would like to say 'Thank you' again for the advice about AVR. I've found working mx200, read firmware (it really difers only in the region 0x500-0x53f). I've flashed it into AVR of my Lexicon and now it works as before!

    Thank you so much!

  • HARMAN_EEldeHARMAN_EElde Posts: 1,144

    @victorchaplinsky said:
    Hi HARMAN_EElde,

    I would like to say 'Thank you' again for the advice about AVR. I've found working mx200, read firmware (it really difers only in the region 0x500-0x53f). I've flashed it into AVR of my Lexicon and now it works as before!

    Thank you so much!

    Excellent news Victor, thanks for the update! You're welcome!

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