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Thread: Korbanth K4 - A build log by a total N00b

  1. #1

    Default Korbanth K4 - A build log by a total N00b

    Korbanth K4 Build Log

    By A. Noob.
    This is my first attempt at wiring my own saber for sound and light. My previous project was a partial conversion of a MR Vader which had a broken LED String so I wanted to be a bit more adventurous for my new project.
    I always liked the design of the Obi-Wan saber from ANH and when JQ Sabers got the Korbanth K4 in stock I decided to take the plunge.

    This is my build process if anyone else is in the same position as I am in case
    1. It might help you
    2. You don’t make the same mistakes I did.


    First of all, I planned my build by deciding which components I needed and how they were to be joined up.
    First, I needed to work out what resistors I needed. I was going for a BBW Tri-Cree which had the following specs.
    • 2 x Blue LED – 3.4 Volts at 1000ma
    • 1 x White LED – 3.15 Volts at 1000ma


    Resistors:
    Blue
    (3.7-3.4)/1 = 0.3 Ohms
    (3.7-3.4)*1=0.3W
    White
    (3.7-3.15)/1 = 0.55 Ohms
    (3.7-3.15) *1 = 0.55W

    I decided to put 0.47 Ohm 1W resistors on all the LEDs because it shouldn’t be too much of a problem for the White which was not going to be on constantly and was close to the requirements for the blue. Also, I got 10 off eBay for 99p.
    The next decision was the driver board. Due to the internal diameter of the K4, the only choice was the Nano Biscotte v4
    My electronic requirements were therefore decided as follows:

    • Tri-Cree BBW
    • 3 x 0.47 Ohm 1W Resistors
    • 18650 Battery
    • Veco 20mm Speaker
    • 2.1mm Switchcraft recharge port
    • Lots of different colour 28 AWG wire. (I already had Black, Red, Blue, Green and Yellow from a previous project so I decided this would do.)
    • Heatshrink
    • Superglue


    After several iterations and consultation, this is the wiring diagram I came up with:
    KKK4__Wiring_V2.jpg

    The next requirement was for a chassis to hold the parts in the hilt.
    I searched for a 7/8” chassis on Shapeways and bought this:
    https://www.shapeways.com/product/S3...custom-chassis.
    After I bought this chassis I found several custom chassis specifically for the K4 with space for a Crystal Chamber. I decided to stick with the 7/8” option as I didn’t want to get too ambitious on what was my first project and the chassis I had bought had easy access to the SD Card.
    To hold the speaker and recharge port I ordered this as I didn’t want to risk destroying the pommel by drilling holes in it:
    https://www.shapeways.com/product/EZ...-recharge-port
    Parts were duly ordered and after a long delay thanks to HM Customs I could get started.

    Day 1
    After a quick test of the Biscotte board to make sure it survived the couriers delicate handling by dry joining the battery to the board, connecting the speaker and bridging the Activation pad to the ground pad. Yay! Sound!
    First task, wiring the Tri—Cree. This took longer and was more fiddly than expected. Trying to pre-tin the pads proved trickier than I thought, Solder refused to stick to the pad despite applying flux beforehand, I put this down to the copper layer on the bottom of the Cree absorbing the heat from the soldering iron but with a bit of perseverance the pads were tinned and the wires attached.

    Once the wires were in place, I threaded the wires through, clipped them to a manageable size, soldered the resistors to the positive wires. I then twisted the other ends of the resistors together and soldered a single wire to that end.
    I then connected the battery to the +ve and -ve connections to the battery to check the wiring. As expected, the Blue LEDs lit up together and the white LED lit up separately from the blue

    Things I learned –
    Use superglue to attach the lens to the Tri-Cree before inserting it into the blade holder. It was a stone bitch getting the lens in and lined up when the LED was fixed in place. At the moment I have to rely on the blade or safety plug to hold the lens in place.
    Stagger the placement of the resistors so they can fit in the neck between the blade holder and the hilt. Don’t twist the resistors together. Wire them individually and join them where they exit the neck.

    Day 2

    The fun part. I threaded the LED wires through the battery holder and with the battery in place, I carefully soldered the LED -ves to the Nano Biscotte.

    I had decided to keep the JST connector on the battery in the belief that if the battery ever failed, it would be easier to replace. I bought a wired female connector, soldered the LED positive to the wire coming from the JST. Combined these into a single wire running to the recharge port battery +ve connection along with yet another wire form the recharge port +ve to the Biscotte.

    The battery positive wire was soldered to the recharge port and two wires from the Recharge port were used, one soldered to the Biscotte, the other to be used for the switch.
    I decided to do a quick test and….

    Nothing.

    I broke out the multimeter and checked for bridged connections on the Biscotte but everything checked out.
    I checked that there was power on the +ve line and it appeared OK.
    At this point I remembered that I hadn’t plugged the SD card back into the Biscotte after removing it while soldering. I inserted the card and tried again. Still nothing. I put an LED across the negative line and the 3.3v pad but it came up dead.
    I took a quick coffee, vape and swear break, thinking I must have damaged the card during my ham-handed attempt at soldering. I tried bridging the ACT and Gnd again and the LEDs blinked into life! The assembly rolled slightly and the lights went out again. After further investigation I found that the +ve connection had come apart inside the heatshrink. With a sigh of relief, I resoldered and rewrapped the joint. Again, everything tested OK.

    I then tried to solder up the speaker. At this point things fell apart. When attempting to solder the speaker wires, the solder pads on the speaker fell off rendering the speaker useless.
    I had ordered a spare Veco speaker so I attempted to wire it again with the same results.

    Result: Two broken speakers. I put in an order for three more Veco speakers because I knew I would need spares and continued with the rest of the build.

    I inserted the assembly into the hilt, carefully prying the switch wires through the hole and tested again.

    Nothing.

    Testing the assembly with the multimeter showed no charge on the +ve line. I removed the assembly and found that the +ve wire had broken off the battery end.
    I went online, ordered a new battery and called it a night

    Things I learned:
    • When inserting the assembly, use a cable tie to hold the battery tightly in the assembly to stop it flopping about and causing solder joints to break.
    • Be very careful when soldering wires to a Veco speaker. If you hold the heat too long on the solder pads, the pads come off and the speaker is now useless. I ruined two perfectly good Veco speakers learning this. And ended up ordering three more


    Day 3

    While waiting for the new battery to arrive I thought I would give repairing the existing one a go.
    Unfortunately, I had to abandon the idea of leaving the JST connections in place as I had to snip them off to get the battery out of the holder.
    The +ve cable was soldered back into place, the recharge cabling rewired to remove the JST connector and checked with the multimeter. Everything now looking good. Power is getting to the board and the LEDs were lighting up when the ACT and -ve wires were connected.

    This time I cable tied the battery into the holder and inserted into the hilt. I removed the cable tie when the battery was being held firmly in place by the hilt, pushed the assembly further down the hilt and fished out the switch wires. A quick test and it seemed all the joints were holding. On power on the blue LEDs lit up and the FoC was working as intended.
    The next step was getting the speaker and recharge port into the holder.

    My recommendation is to avoid these holders like the plague. I had to snip two of the support struts out of the way to get the recharge port in and wrestling the speaker in behind it was a nightmare. The gap between the recharge port and the speaker can be measured in mm’s and the solder joint on the speaker wires kept breaking. Eventually the speaker was in place and the assembly superglued into the chassis
    If I was doing this again I would bite the bullet and put the recharge port in the pommel and just use a normal speaker mount in the base

    So my saber is now finished and working a charm but in retrospect, this was not a build I would recommend for a beginner like me. The narrow constraints of the K4 means that it is not forgiving for mistakes and the lack of room to manoeuvre parts means every wire has to be measured carefully.
    My main criticisms of the K4 hilt have to do with the blade holder, there is no room to mount a heatsink so you have to rely on the holder itself and there isn’t much room left after the lens is in place to insert the blade and be confident it will stay in place. Another critique I have is that the hilt did not come with retention screws fopr the blade. I had to dig up some M5 screw and cut them to size
    20171105_172050.jpg

  2. #2

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    Hey @Vypr ! Your windvane is on upside down. Great first build log otherwise!

  3. #3

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    Nice build.

    You can do blue, blue, white without the PEX. Just common up the blues onto a single wire to pad 1, and white to pad 2. That'll keep the PEX out of there, save some cramped room in the K4.
    Nice saber though. I'm working on one now.

    Tom

    "Let the past die."

  4. #4

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    Well windvanes going to have to stay upside down as I do not want to risk cutting the LED wires and screwing everything up (again)

    TOm, well spotted, looks like I uploaded the wrong diagram, this is the proper reworked version I used:
    wiring diag.jpg

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    I'm also working on a K4 but I don't have the shapeways chassis. I found one for free on thingiverse and it works 'ok' but it's pretty cramped and not really that optimal. I think I'll live with it for a while and try the shapeways version with an RGB star when I feel like rebuilding this sucker again. I also forgot to put the lens on before the led star went into the emitter, but I managed to get it seated with a couple dabs of superglue, so fingers crossed. What are you using for a blade plug?

    What I'm really having trouble with is the transistor push buttons. The buttons/pcb seems really difficult to line up with the clamp properly so the bottom one, in particular, is super-sensitive. Did you have any troubles with the clamp/buttons?

  6. #6

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    Quote Originally Posted by Vypr View Post
    • If you hold the heat too long on the solder pads, the pads come off and the speaker
    Been there, done that.

    K4 is my next build, as well (have to finish my Mando kit first). Thanks for sharing your experience.

  7. #7

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    Quote Originally Posted by SA22C View Post
    I'm also working on a K4 but I don't have the shapeways chassis. I found one for free on thingiverse and it works 'ok' but it's pretty cramped and not really that optimal. I think I'll live with it for a while and try the shapeways version with an RGB star when I feel like rebuilding this sucker again. I also forgot to put the lens on before the led star went into the emitter, but I managed to get it seated with a couple dabs of superglue, so fingers crossed. What are you using for a blade plug?

    What I'm really having trouble with is the transistor push buttons. The buttons/pcb seems really difficult to line up with the clamp properly so the bottom one, in particular, is super-sensitive. Did you have any troubles with the clamp/buttons?
    I'm using a standard Style 4 1" safety plug. It juts out the end so it's not ideal but it does the job of not blinding me if I accidentally peek down the emitter (I would fail any gun safety test ) You can get safety plugs for the K4 at Shapeways but they run to around £30 -£40 which I don't think is worth it.

    I did have problems with the buttons. The lower button does not work at all, there's no movement in it as I think the upper button is causing the lower button to rock upwards. The upper button works fine and since the NBv4 only uses one button I am satisfied with it.

    The other item I forget to get is a battery charger so I bodged one together from the power bank the battery originally came in and an old, broken power supply with the correct style plug on it. Takes a bit longer to charge but does the trick.

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    Hi!
    Thanks for sharing your build!

    A good point to give your opinion about the chassis. I was wandreing if it was good stuff...

    See your for the next saber !

    Paul

  9. #9

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    Update:
    things went a bit south today, the sound stopped working.
    Was getting a constant clicking noise when the kill switch was removed. Thought I'd blown another speaker so took the speaker off. without the speaker, the LED's came on. Popped one of the spare speakers in and got the same thing. A quick google of the issue revealed that the problem was likely the battery no longer providing sufficient current. Since I had had problems with that battery I decided to replace it with the one I ordered when the lead popped off the current one.
    Here's where I hit the first problem with this model of hilt. The metal buttons have to be superglued onto the tactile switches, attempts to disassemble the chassis will break the tactile switches when you try to prise the buttons off.


    With the battery replaced I went for a dry run before reassembly and found that the solder joint to the resistor bundle had come loose and on inspection of the Cree, a solder joint had come loose there as well.
    I took this as an opportunity to completely rewire the LED, placing the resistors in the neck and glueing the lens to the Cree before inserting it into the blade holder.
    After a quick check of the assembly (Had to resolder the +ve wire again as one of the blue LEDs wasn't lighting up. Nearly blinded myself checking that) I inserted the chassis back into the hilt.
    Replacing the tactile switches was a simple process although you have to be wary that the board is the right way up as the solder pads are only on one side.

    To summarize what I have learned from this build:

    1. Try and use 1W resistors so you can get them in the neck. Bigger may be better but not when space is at a premium.
    2. Stagger the placement of the resistors
    3. Glue the lens onto the Cree before inserting it into the blade holder
    4. Check your solder joints as you go as mistake can lead to a lot of hassle if you have to disassemble to get to the fault.
    5. A multimeter is a handy troubleshooting tool
    6. Tactile switches are easy to replace if they break
    7. Be patient and don't rush through, check each part as you complete it
    8. Soldering irons are not pens, don't be tempted to hold it in your mouth when doing quick adjustments
    9. You can never haver too much heatshrink.


    Thanks for reading and good luck to all you other K4 builders!

  10. #10

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    Thanks for the detailed log Vypr. Here's my 2c, now that I've got mine completed

    1) I didn't use resistors, because the blues and whites are close enough to battery voltage that I simply reduced the drive and fdrive parameter on the board. Based on the instructions in the manual, so long as you don't go beyond 20% reduction, it's safe to use those parameters to adjust the LEDs rather than use resistors. Given the space premium on the K4, it seemed like a worthwhile effort to not have to use resistors.
    2) A little bit of tape over the weathervane threads does wonders to snug it up.
    3) I'm really in love with the trans white blade with 2ft of giftwrap and a hollowed-out shine-through tip. It's brighter (at the base) than my neopixel Graflex.

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