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    providing phantom power to a 5 pin midi footswitch

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    YoYoNinjaBoy

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    Join date : 2017-01-21

    providing phantom power to a 5 pin midi footswitch

    Post by YoYoNinjaBoy on Sat Jan 21, 2017 5:18 pm

    the manual of the TM36 says it requires a 7 pin to transfer phantom power but there doesn't seem to be any 7 pin to 5 pins on the market that are capable of such. The Rocktron rmm900 7-5 with the ac adapter thing doesn't transfer power through the 7 pin and the adapter is a male end that doesn't seem to fit any of my female adapters.
    It's a Midi Moose.

    what do?

    Thanks!
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    bordonbert

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    Re: providing phantom power to a 5 pin midi footswitch

    Post by bordonbert on Mon Jan 23, 2017 8:02 am

    I'm not sure why you would want a 7 to 5 pin cable, you are going to find compatibility problems between the H&K and the Moose.  The Rocktron cable is a straight through 7 pin, that just means that each pin at one end is connected directly to the same pin at the other end.  With that cable, if you want to use phantom power both devices need to have it on the same pins at each end.  It isn't like that in your case and there is another problem to overcome later.

    The MIDI Moose needs power through its 5 pin connector on pins 1 and 3.  They have routing diodes inside so it doesn't matter which pin of the two you use for +ve and which for -ve.  You could make up a special custom cable with the power going onto pins 6 and 7 of a 7 pin plug at the TM36 and coming out on pins 1 and 3 of a 5 pin plug at the Moose end.  However the voltages are not compatible!  You would then need a small regulator unit to drop the voltage down to around 15V which you would have to put in the line before the Moose.  I don't honestly think all of that is worth it unless you're technical enough to make one up yourself, there is a simpler solution lower down.

    That voltage incompatibility is the bigger problem.  I think you will find the phantom power from the TM36 is really intended for the FSM432 footswitch which is designed to accept what the TM36 gives it as DC and the TM36 is just using the lines it already has available inside.  I haven't a schematic for the TM36 but the GM36, which would probably be identical in this area, shows +22V DC fed onto pin 6 of the MIDI socket through a 10R current limit resistor and a 0.2A fuse (note that's 200mA).  Some MIDI controllers will eat up much more than that but the MIDI Moose says it requires only 9V @ 100mA minimum so currentwise you would be ok.  However, 22V is not within its 9-15V range, it could be damaged by using the TM36 supply as it comes out of the amp.

    For me, I would suggest that your best option is to power the Moose from its normal power pack.  I have been through something similar to this.  I just got a very long 2.1mm DC extension lead something like this DC Extension and strapped it to the midi cable so it ran out to the controller alongside it.  (There is no danger of affecting signal quality in any way!)  The power block can then be plugged in alongside the amp away from your playing area.  It's even easier if you already use a pedalboard with a built in supply, (I'm not a pedal junkie so it wasn't an option for me).
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    YoYoNinjaBoy

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    Re: providing phantom power to a 5 pin midi footswitch

    Post by YoYoNinjaBoy on Mon Jan 23, 2017 2:02 pm

    WOW, thank you so much, I guess I'll abandon that idea. I recieved the moose as part of a deal for the head and wish I was told this at the time. I was excited to be able to have minimal cableage and no batteries. Cheers!
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    YoYoNinjaBoy

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    Re: providing phantom power to a 5 pin midi footswitch

    Post by YoYoNinjaBoy on Tue Jan 31, 2017 8:15 pm

    just in case anybody else needs help this cable did the trick

    http://www.ebay.com/itm/162029776806
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    bordonbert

    Posts : 767
    Join date : 2015-01-28
    Age : 97
    Location : Southern England

    Re: providing phantom power to a 5 pin midi footswitch

    Post by bordonbert on Tue Jan 31, 2017 10:38 pm

    Great find!  Here is one from the UK I came up with - DesignACable.com 7-5pin.  A couple of points:

    It's very expensive for what it is.  A 6m 5-5pin MIDI cable from Kenable is - - - £1.52 under ($2) and they produce good quality totally reliable cables.  Now granted that is not the specialist 7-5pin that you need in this case so it should be a bit more, but there is no reason to charge $31.33 for the same thing.

    Van Damme cable?  Absolutely not necessary in any Universe, it makes no improvement to the cable in any way over any other sturdy cable.  There is no music signal carried here only MIDI commands and they plain don't care, it has absolutely no influence on the quality of sound nor does it make signal transfer any more reliable at this length.

    It's a pity more guitarists don't solder, it saves a fortune and allows you to get up any odd specialist stuff like this that you need very quickly.  For $2 for a standard cable and a new 7pin plug you could cut the 5pin off one end and replace it with the 7pin in about 5 minutes.  But that's all beating my gums in the wind if you don't solder of course.  Wink

    What is the pinout of the new cable?  As it works I assume it connects pins 6/7 at the amp, (the two with the gap between them), to pins 1/3, (the outer two on the ends of the pin line).

    Now to the real question.  How did you get round the power supply restrictions?  Are you really feeding your Moose at +22V from the TM?  That may work but keep an eye on the Moose case for hot spots as that is out of spec, Moose specify 9-15V as I said.  Inside you have a voltage regulator to drop the supplied voltage down to the correct level for the insides to work.  It may work at +22V in but it has to dissipate all of that overvoltage as heat so you are making it work much hotter than it has been designed to do!  These usually are able to dissipate about 0.25W without heatsinking but above that by much a heatsink would definitely be needed.

    If you are taking 100mA then the 10R inside the TM will drop it down to +21V.  Let's assume it needs 5V for its electronics which is common.  At 9V feed your internal regulator is dropping 4V @ 100mA which is 400mW, while at 15V feed it is 1W so we can assume they will have put some sort of heatsinking in place.  Then we go out of spec.  At 21V feed it's climbed to 1.6W.  If the regulator is not heatsinked to cope with that amount of heat then it will shut down.  If you experience periods where it stops functioning then it comes back to life that could be what is happening.

    I'm glad you got it up and running, it's a shame it was so expensive but that's less of an issue, but I would urge you to keep an eye on things.  If you should develop a problem and the regulator burns out the Moose manufacturers will be able to spot a unit which has blown because of overvoltage.  If they do, it is definitely a case for - warranty voided!

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