I decided to do a bit of modifying on my FCB1010 at the weekend. In an effort to cut down on stage clutter, did a phantom power mod to it with the addition of the option to run from batteries as well. After some research I discovered that the unit actually operates on 5v DC, even though its own internal power supply is 10v AC. This goes into a bridge rectifier that converts it to DC and then there's a 5v regulator on the main board that reduces this down to a steady 5v operating voltage.
The revelation that the unit uses 5v was my eureka moment, up to then I'd been scratching my head about the best way to cobble together a battery delivering 9v DC with a decent enough capacity to give a long operating time between charges. Once I knew I could use a 5V supply, I decided to use a portable USB charger block as the power source. Obviously a smaller unit could be found that could be built into the FCB itself (with an external USB port for charging), but as this was intended to be a quick & dirty prototype I elected to use a flying lead and make the battery connection external. This also gives me the option to power it from any USB source, and a later mod will probably include an external USB socket and a USB/midi interface installed into the unit for easier programming (killing two birds with one stone etc.).
With that in mind, I found an ancient Sony Ericsson USB cable and cut a decent length of it off:
Next I located a suitable position for the mains/phantom power switch (DPDT on-on) that would be close enough to the existing power input to the board that I could reuse the existing wires, but out of the way of everything. I found a point on the back below the screen, positioned the hole to miss the main circuit board and got the drill out:
The I turned my attention to the insides of the FCB. The yellow wires running to the lower right of the main board are the power wires from the internal power supply. You can see the switch I installed at the top centre and the voltage regulator is on the top right of the main board, bolted to the chassis as this doubles as a heatsink for the regulator:
I cut through the original power wires running from the power supply at a point that would allow both of the cut ends to reach my new switch:
I then stripped the end of the USB cable, removing everything bar the red & black power wires:
Seeing as I had a considerable length of the USB cable left over (and I was feeling lazy) I stripped that down and reused the surplus red & black wires to provide the phantom power connection to the midi out connection:
I removed the midi port board from the FCB, flipped it over and soldered the wires to the underside. If you're using a 5 pin connection like this, pins 1 & 3 are the two you need to use for phantom power:
Next, I soldered everything up to the switch, Not my finest work, but it does the job and it was a confined space (that's my excuse and I'm sticking to it). If you aren't adding a switch and just want to make your FCB permanently phantom powered you can just connect the wires added to the midi board directly to the power wires to the main board. Polarity doesn't matter due to the AC nature of the original supply, the bridge rectifier on the board will sort out the polarity. However, if you're adding a switch you want to connect the wires from the board to the centre terminals of your switch. The wires from the onboard power supply go to the OPPOSITE contacts to the side you want the switch to point when you are on mains power and the phantom power wires go to the remaining set of contacts:
This second picture should hopefully make the wiring a little clearer:
The eagle eyed will spot that I'd soldered the USB lead to the centre contacts as well (as the was a proof of concept I wasn't adding a switch to the USB power at this point). I'd done this as I was being lazy and didn't want to remove the main board to solder directly to the regulator legs. This proved to be a mistake as voltage losses between the power input and the regulator meant the unit didn't work.
As my laziness had bitten me in the arse, I removed the USB cable from the switch and did what I should have done in the first place removed the main board. I then soldered the USB lead to the regulator contacts, trying to use the minimum amount of heat possible so as not to destroy the regulator. As you can see from the next picture, the black lead goes to the middle contact and the red to the one closest to the outside of the board:
A quick test proved that I'd been successful, I now have an FCB that can run from a USB power source (and you get to see my layout for triggering my sample pad):
Finally, I put the bottom back on the FCB and added some labels to the switch. Yes, the USB lead is just sandwiched in there for now, but as I said this was a quick test of concept:
So, I'm now left with an FCB that can run from a mains supply, phantom power over midi or USB power. That's quite handy as my sample pad is also USB powered, so I can use one source to power them both. If you were planning to phantom power your own FCB, you'll need a suitable adaptor for the other end of the midi cable to provide the power. As for mine, this is the first stage of an ongoing project. Future plans for this unit include:
Installing an external USB socket
Installing an on/off switch for the USB power
Installing a USB/midi interface within the unit for ease of programming
The revelation that the unit uses 5v was my eureka moment, up to then I'd been scratching my head about the best way to cobble together a battery delivering 9v DC with a decent enough capacity to give a long operating time between charges. Once I knew I could use a 5V supply, I decided to use a portable USB charger block as the power source. Obviously a smaller unit could be found that could be built into the FCB itself (with an external USB port for charging), but as this was intended to be a quick & dirty prototype I elected to use a flying lead and make the battery connection external. This also gives me the option to power it from any USB source, and a later mod will probably include an external USB socket and a USB/midi interface installed into the unit for easier programming (killing two birds with one stone etc.).
With that in mind, I found an ancient Sony Ericsson USB cable and cut a decent length of it off:
Next I located a suitable position for the mains/phantom power switch (DPDT on-on) that would be close enough to the existing power input to the board that I could reuse the existing wires, but out of the way of everything. I found a point on the back below the screen, positioned the hole to miss the main circuit board and got the drill out:
The I turned my attention to the insides of the FCB. The yellow wires running to the lower right of the main board are the power wires from the internal power supply. You can see the switch I installed at the top centre and the voltage regulator is on the top right of the main board, bolted to the chassis as this doubles as a heatsink for the regulator:
I cut through the original power wires running from the power supply at a point that would allow both of the cut ends to reach my new switch:
I then stripped the end of the USB cable, removing everything bar the red & black power wires:
Seeing as I had a considerable length of the USB cable left over (and I was feeling lazy) I stripped that down and reused the surplus red & black wires to provide the phantom power connection to the midi out connection:
I removed the midi port board from the FCB, flipped it over and soldered the wires to the underside. If you're using a 5 pin connection like this, pins 1 & 3 are the two you need to use for phantom power:
Next, I soldered everything up to the switch, Not my finest work, but it does the job and it was a confined space (that's my excuse and I'm sticking to it). If you aren't adding a switch and just want to make your FCB permanently phantom powered you can just connect the wires added to the midi board directly to the power wires to the main board. Polarity doesn't matter due to the AC nature of the original supply, the bridge rectifier on the board will sort out the polarity. However, if you're adding a switch you want to connect the wires from the board to the centre terminals of your switch. The wires from the onboard power supply go to the OPPOSITE contacts to the side you want the switch to point when you are on mains power and the phantom power wires go to the remaining set of contacts:
This second picture should hopefully make the wiring a little clearer:
The eagle eyed will spot that I'd soldered the USB lead to the centre contacts as well (as the was a proof of concept I wasn't adding a switch to the USB power at this point). I'd done this as I was being lazy and didn't want to remove the main board to solder directly to the regulator legs. This proved to be a mistake as voltage losses between the power input and the regulator meant the unit didn't work.
As my laziness had bitten me in the arse, I removed the USB cable from the switch and did what I should have done in the first place removed the main board. I then soldered the USB lead to the regulator contacts, trying to use the minimum amount of heat possible so as not to destroy the regulator. As you can see from the next picture, the black lead goes to the middle contact and the red to the one closest to the outside of the board:
A quick test proved that I'd been successful, I now have an FCB that can run from a USB power source (and you get to see my layout for triggering my sample pad):
Finally, I put the bottom back on the FCB and added some labels to the switch. Yes, the USB lead is just sandwiched in there for now, but as I said this was a quick test of concept:
So, I'm now left with an FCB that can run from a mains supply, phantom power over midi or USB power. That's quite handy as my sample pad is also USB powered, so I can use one source to power them both. If you were planning to phantom power your own FCB, you'll need a suitable adaptor for the other end of the midi cable to provide the power. As for mine, this is the first stage of an ongoing project. Future plans for this unit include:
Installing an external USB socket
Installing an on/off switch for the USB power
Installing a USB/midi interface within the unit for ease of programming