# Question about the older Marantz monoblocs



## audionut71 (Dec 30, 2008)

Hey Shacksters,

I am hoping that you can help me with a puzzler that I have been trying to whup for a while. I own 4 of the Marantz MA 500 mono THX amps. They use some sort of proprietary trigger system that Marantz refers to as the D-bus that uses a standard RCA as the plug for the turn on lead. Does anyone have any idea what signal this requires to make them turn on? I have been using an external switcher to remotely power them, but would prefer to use their internal turn on circuitry. Any help would be appreciated.


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## tonyvdb (Sep 5, 2007)

As far as I know it would be a 12vDC trigger (12v has been used for many years and is a standard). you could easily try using a power supply that has less voltage, try 5vDC first and work your way up the +being the center pin.


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## lcaillo (May 2, 2006)

Sorry, none of the service manuals that I have for Marantz have anything about D-Bus. Have you contacted Marantz?


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## audionut71 (Dec 30, 2008)

Tony,
I have tried the 12 volt experiment w/ both polarities with no success.

Loenard,
There is no discussion of the turn on scheme at all? When I get home I'll post some model #' s of recievers or processors that my MA 500 lists in its manual. I have written Marantz twice with no reply.

:gah::help::gah:


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## Wayne A. Pflughaupt (Apr 13, 2006)

Usually better to call than write. If all else fails, try that. If nothing else, maybe you can order an owners or repair manual.
http://us.marantz.com/Contact-us.asp

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

Usually better to call than write. If all else fails, try that. If nothing else, maybe you can order an owners or repair manual.
http://us.marantz.com/Contact-us.asp

Regards,
Wayne


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## audionut71 (Dec 30, 2008)

wayne,
I have the owners manual for the amps, and it references a special code that gets sent, and even has a switch to alternate between different codes that Marantz uses, but what these signal are is not discussed.



Wayne A. Pflughaupt said:


> Usually better to call than write. If all else fails, try that. If nothing else, maybe you can order an owners or repair manual.
> http://us.marantz.com/Contact-us.asp
> 
> Regards,
> Wayne


_Posted via Mobile Device_


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