Behringer BSY600 Bass Synthesizer

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Behringer BSY600 Bass Synthesizer

Postby JiM » 28 Apr 2011, 23:53

Hi folks !
I've recently bought this little synth toy, and i couldn't resist : i had to have a look inside. And do some reverse-engineering.

Here is the result : gutshots and preliminary schematic.
There are still missing parts, and probably errors, but most of the working principles are visible :
  • The ATmega16 takes care of the "user interface", aka pots and leds, and also holds the program for the DSP (because he has the only Flash memory onboard)
  • The Freescale DSP56364 gets the audio from the AKM4552 codec, and processes it in its internal memory
  • Both processors are linked by a SPI link, which is mostly accessible at the programming header
  • There are some oddities, such as Reset, NMI and MODB tied together, or the ATmega driving the output transistors ... the feedback loop of the first opamp looks strange too.
  • The clock generator IC8 is unknown, the makings on the SOT23-6 package looks like CJ4R, or CU4R

Does anyone have improvement ideas, advice on dumping the SPI link, or error corrections ?
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Re: Behringer BSY600 Bass Synthesizer

Postby snyder80 » 25 Jun 2011, 13:14

Hi Jim!

Awesome tracing job! Saves me a lot of time.
I try to compare my RV600 Pedal to the Tonecore Schematic (inside TCDDK Hardware Guide.pdf), to get rid of the slight constant hissing noise. Briggs simple and easy LPF-Filter mustnt be the only way to handle the noise in these Pedal.

I changed the TL062 to TL072 but that didnt do realy a thing.

Either i suspect the hissing (coupled with some varying rumbling growl, depending on the Pedals settings) is there due of cheap/lack of supply filtering (1591 or ak4552), PCB-trace design.

Sadly some Parts in my pedal i couldnt identify ( 2x CCB Transistors and the IC8 - mine is coded "VU4"). Did you make any progress so far?

Greetings,

snyder80

EDIT: C21,22, 23 should be 100n according to L6 and Freescale documents.
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Re: Behringer BSY600 Bass Synthesizer

Postby JiM » 26 Jun 2011, 19:28

snyder80 wrote:I try to compare my RV600 Pedal to the Tonecore Schematic (inside TCDDK Hardware Guide.pdf), to get rid of the slight constant hissing noise.

Thanks for pointing to the TCDDK documents, it helps a lot to understand the difference between ToneCore and RSM.

snyder80 wrote:Either i suspect the hissing (coupled with some varying rumbling growl, depending on the Pedals settings) is there due of cheap/lack of supply filtering (1591 or ak4552), PCB-trace design.

You may have a look at the switch-mode DC-DC converter (MP1591) maybe it's producing some HF-induced noise.
The pre-emphasis thing is also something to look at, it's intended to reduce noise, unless the noise comes in before boosting treble.
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Re: Behringer BSY600 Bass Synthesizer

Postby snyder80 » 26 Jun 2011, 21:34

Hi!
Good to know i could help you with that doc, to me its "slightly" too much because of my personal EE/DSP knowledges...

First I was happy to find the L6 Schems, but sadly they differ alot to the SYB/RV600. Especially in the IN/Out Buffer section and the "PSU".

I first thought "CCB" could be some kind of dual Diodes or Mosfets, but google tells it should be 2SC3326B BJT´s.

The hissing is a lot reduced if the "output"-IC´s r30/32 in your schem are bridged (for less gain). But it´s not the wet signal that´s hissy, its the dry.
Also the Input jacks are slighty microphonic ("knocking test").

Maybe you could be right with the 1591 oscillating. Any hints to prevent that? I added a 220uF II with C2 (VCC out after L3), but it didnt do anything, too.
Another idea could be a 10R between AGND and DGND, but i think thats too hard to mod in the Behringer Design, since both GND´s seem to be identical.

Should i try to mod/adept the 1591 to the specs in the datasheet (except for +8,04 V DC)?

Greetings,
snyder80
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Re: Behringer BSY600 Bass Synthesizer

Postby jonphilpott » 01 Mar 2012, 00:00

I'm interesting in getting one of these pedals for some hackery (considering its similarity to the line6 tcddk), I'm thinking that it's likely the ISP disable fuses in the AVR16 have not been set given that there's an ISP header on the board.. or maybe that's a foolish assumption! Has anyone attempted to hook up to this header and see whats up?
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Re: Behringer BSY600 Bass Synthesizer

Postby JiM » 03 Mar 2012, 21:11

jonphilpott wrote:I'm interesting in getting one of these pedals for some hackery (considering its similarity to the line6 tcddk),

I would suggest getting one of the delays, reverb or pitch shifter, for the presence of external memory. Then it depends on the number of knobs, switches and either stereo input or mono + expression.

jonphilpott wrote:I'm thinking that it's likely the ISP disable fuses in the AVR16 have not been set given that there's an ISP header on the board.. or maybe that's a foolish assumption! Has anyone attempted to hook up to this header and see whats up?

I'm doing the opposite assumption (but i'd love being wrong on that question :blackeye). The headers are used in factory once, and Behringer is likely to set the lock bits, to avoid further chinese copies. In case of problem, they can erase the chip to clear the lock bits and program it again.
I did not try an ISP there, i'm still planning to dump the DSP code from the SPI line. I tried with an Arduino loaded with BusNinja with little success, i guess a real BusPirate would be much better for the job.
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Re: Behringer BSY600 Bass Synthesizer

Postby jonphilpott » 06 Mar 2012, 18:41

JiM wrote:
jonphilpott wrote:I'm thinking that it's likely the ISP disable fuses in the AVR16 have not been set given that there's an ISP header on the board.. or maybe that's a foolish assumption! Has anyone attempted to hook up to this header and see whats up?

I'm doing the opposite assumption (but i'd love being wrong on that question :blackeye). The headers are used in factory once, and Behringer is likely to set the lock bits, to avoid further chinese copies. In case of problem, they can erase the chip to clear the lock bits and program it again.
I did not try an ISP there, i'm still planning to dump the DSP code from the SPI line. I tried with an Arduino loaded with BusNinja with little success, i guess a real BusPirate would be much better for the job.


Right - my understanding would be that the device could still be reprogrammed by using the high-voltage mode to rewrite the firmware, or if worse comes to worst, unsolder the device and replace it with a new one :twisted:
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Re: Behringer BSY600 Bass Synthesizer

Postby JiM » 06 Mar 2012, 22:21

IIRC the ATMega can be reprogrammed with the ISP anytime.
BUT if the lock bits are set, you can't readback the program. You have to erase the whole Flash to reset the lock bits.
This is intended to forbid reverse-engineering of the program :slap: but one could still load his own firmware.
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Re: Behringer BSY600 Bass Synthesizer

Postby jonphilpott » 06 Mar 2012, 22:38

JiM wrote:IIRC the ATMega can be reprogrammed with the ISP anytime.
BUT if the lock bits are set, you can't readback the program. You have to erase the whole Flash to reset the lock bits.
This is intended to forbid reverse-engineering of the program :slap: but one could still load his own firmware.


There's a set of lock bits that also disables the SPI programming interface, see SPIEN bits in this sheet:

http://www.avrfreaks.net/modules/Freaks ... DN_020.pdf
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Re: Behringer BSY600 Bass Synthesizer

Postby Siro78 » 31 Jul 2013, 13:36

Hi guys.
I have disassembled my DD600 for investigate the constant noise that it has so. The schematic is very similar to the showed on this post, except for the presence of an external SDRAM needed for long delay time.
A correction on schematic posted is that the 1591 switching regulator output 3.3V and not 5V!
I try to replace the 1591 with a 9V->3.3V linear regulator but the result is that the regulator overheats a lot, the current absorption from 80mA become 200mA and the noise not disappear.
I think that the problem is to search on inductive filter or the pcb layout.

Also my DD600 eat a lot of high frequency in all mode. It's possible because it not have the classical FET input signal buffer?

Bye
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Re: Behringer BSY600 Bass Synthesizer

Postby Seven64 » 01 Oct 2013, 06:21

How can you tell the pot values?
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Re: Behringer BSY600 Bass Synthesizer

Postby modman » 20 Jul 2014, 22:23

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