Phantom powering a Liquid Foot 12+ (WARNING)

The attached photo should remove any further doubt. This is the section of the main board near the MIDI ports of the AxeFX II. You can clearly see a SMD component that is fried, which appears to be labeled L42. So at the very least this part of the circuit is lost, and since it is SMD it will be nontrivial to replace. The MIDI IN port is also of the type that can't be easily redone to more directly connect the phantom in port to Pin 6&7, so the only apparent solution is the one offered by Liquid Foot or a homemade adapter that does the same.

AxeBurned.jpg
 
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This. Phantom power passes through the motherboard to get to the MIDI In jack. The burned component—an inductor, I think—connects directly to that jack. It couldn't handle the current drawn by the foot controller, and it fried. Ouch!
 
The attached photo should remove any further doubt. This is the section of the main board near the MIDI ports of the AxeFX II. You can clearly see a SMD component that is fried, which appears to be labeled L42. So at the very least this part of the circuit is lost, and since it is SMD it will be nontrivial to replace. The MIDI IN port is also of the type that can't be easily redone to more directly connect the phantom in port to Pin 6&7, so the only apparent solution is the one offered by Liquid Foot or a homemade adapter that does the same.

View attachment 10338
Grieswig: GREAT picture (of an admittedly sad situation) that certainly ends the burning smell mystery. I am hopeful FAS tech folks will chime in here, ID the mystery component formerly residing in good health at L42, and comment on its demise. This looks to be a good item of the Sticky/Wiki variety as many Axers use products like the LF that might use >9V transformers.

Sorry to hear about your situation, but thanks for sharing it!
 
Interesting, but this actually sounds very different. The component that Liquid Foot says burned out is something inside the AxeFX II itself, not the external adapter powering the MIDI foot controller. But maybe they are related.

yes, but the end result was the same... it eventually stopped frying my adapters, and just stopped passing power. Very lucky it didnt fry my LFJR. I did something similar to Jeff's solution, just wired it directly to the patch panel.. bypass the axe totally, still not happy with a brand new unit frying 3 adapters and then just stoping to work as it should. I need to open to see if the same component is dead.
 
Wow. Not good at all. Javajunkie and several others have the new LF+ models and I've been waiting for them to weigh in.
 
yes, but the end result was the same... it eventually stopped frying my adapters, and just stopped passing power. Very lucky it didnt fry my LFJR. I did something similar to Jeff's solution, just wired it directly to the patch panel.. bypass the axe totally, still not happy with a brand new unit frying 3 adapters and then just stoping to work as it should. I need to open to see if the same component is dead.

Thing is, in your case it actually sounds like there might have been an internal short in the circuit (or the cable), the opposite of an open: adapters burn out from having too much current draw. A short circuit or trying to power something that demands more current than the adapter can supply will burn out the power supply. Facing an open circuit doesn't give power supplies any problem, because there is no current draw. These two circumstances sound similar only in that they both affect phantom power, but it doesn't seem likely to me that they are due to the same design deficiency.
 
This. Phantom power passes through the motherboard to get to the MIDI In jack. The burned component—an inductor, I think—connects directly to that jack. It couldn't handle the current drawn by the foot controller, and it fried. Ouch!

Ferrite bead
 
Wow. Not good at all. Javajunkie and several others have the new LF+ models and I've been waiting for them to weigh in.

I blew one out. I believe I commented a while back. Looks like that post got pruned. I wouldn't use anything over 1000 ma in the axefx II phantom jack. I believe when you order the lf now and specify youvare using it for an axefx, they send a 1000 ma adapter with the correct barrel size.

That will not work if you are using 2 lf+ s.
I made a custom cable where I don't need to plug in to the axefx at all.
 
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I blew one out. I believe I commented a while back. Looks like that post got pruned. I wouldn't use anything over 1000 ma in the axefx II phantom jack. I believe when you order the lf now and specify youvare using it for an axefx, they send a 1000 ma adapter with the correct barrel size.

That will not work if you are using 2 lf+ s.
I made a custom cable where I don't need to plug in to the axefx at all.

I have been using the MFC adapter. But just with 1 LF+. Since a second one will be joining the fray, can you please illuminate me about the custom cable?

Thanks,
John
 
i can verify this.. I had an ultra for a long time many years (since v4 firmware) in same rack with the same custom patch panel, same adapter. Powered my fx1 for years, then when i got the Liquidfoot, it powered it fine as well, no problems.

pulled out the axe 1, swapped it out for the axe2, plugged everything back up and my power adapter lasted about 15 minutes, then burned out, tried another adapter... same thing. totally rewired from scratch with brand new cables, burned out yet another adapter. Finally gave up, and wired the adapter to the patch panel, no problems since. I can verify that the axe is not supplying power through the midi cable, nothing comes out. No fancy adapters, just a 9v ac adapter i've used to power my fx1 for ages.

I had that happen with Besttronics 7 pin MIDI cables. I have no idea why the worked fine with MFC but fried out 2 different adapters w/ the LF pro. I would thing it was the cable but it did the same thing with 2 different new cables. When I used a cheapo 7 pin cable I had laying around, it worked fine w/ the Axe-fx and the LF pro.
 
I have been using the MFC adapter. But just with 1 LF+. Since a second one will be joining the fray, can you please illuminate me about the custom cable?

Thanks,
John

The MFC is 9V, LF+ is 12V. It works but you are probably under supplying the LF+ with power. I would confirm with FAMC that that is okay.

As for the cable, I took a female barrel connector from a Rocktron 5 to 7 pin cable. I couldn't use it with the Axe-fx because the piece of junk on has 5 wires instead of 7.
So I took the pigtail off of it and wired it to pins 6 and 7 of a bestronics 7pin cable I have. I plug the power supply into the pigtail.

I will do this from now on for phantom power. There is no way it can hurt the processing unit this way.
 
The MFC is 9V, LF+ is 12V. It works but you are probably under supplying the LF+ with power. I would confirm with FAMC that that is okay.

As for the cable, I took a female barrel connector from a Rocktron 5 to 7 pin cable. I couldn't use it with the Axe-fx because the piece of junk on has 5 wires instead of 7.
So I took the pigtail off of it and wired it to pins 6 and 7 of a bestronics 7pin cable I have. I plug the power supply into the pigtail.

I will do this from now on for phantom power. There is no way it can hurt the processing unit this way.

thats pretty much what i did, took a female barrel and wired it to the pins on my female 7 pin xlr on my panel. This is very odd though, I dont understand why it worked with the ultra and not the 2. Again mine was the same adapter and cable setup i've been using for ages, road tested mother approved :)

It appears the ultra was just a direct wire to the pins inside the unit, on the 2 it's going through some kind of circuit on the motherboard.
 
thats pretty much what i did, took a female barrel and wired it to the pins on my female 7 pin xlr on my panel. This is very odd though, I dont understand why it worked with the ultra and not the 2. Again mine was the same adapter and cable setup i've been using for ages, road tested mother approved :)

It appears the ultra was just a direct wire to the pins inside the unit, on the 2 it's going through some kind of circuit on the motherboard.

It is just going through that Ferrite bead.
 
Need to Sticky/Wiki this info

This cable will work and keep the power outside the Axe Fx box:

View attachment 10345 Rocktron RDMH900 (If you don't like Rocktron, I am sure others make a similar unit)

The 5 pin end will plug into the Axe Fx 7 pin socket to transfer data, the 7 pin end goes to your foot controller to provide data and power, while the wall wart stays neatly tucked into your rack. I used it with another unit before I had the Axe Fx.

Considering how many people appear to be using or planning to use LF 12 volt equipment, it would be a good thing to add this to the sticky/wiki info available, don't you think? It doesn't affect me personally (using an MFC-101) but could save others some grief. Any chance of passing on a request to Cliff about adding a little warning label on the back of the Axe Fx by the phantom plug not to go over a certain power/load?

Thanks for all the info and help!
 
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