Installing a BTC "Spectre" MOSFET in a KWA 2GX gearbox
Mar 22, 2014 2:26:42 GMT -5
Post by triggs (SABR) on Mar 22, 2014 2:26:42 GMT -5
Full Album Review - Black Talon Concepts "Spectre" MOSFET
PERFORM THESE MODS AT YOUR OWN RISK. TAL or myself are NOT responsible for any damages or malfunctions that may happen as a result of performing this mod.
Modifying a KWA 2GX gearbox for a Black Talon Concepts (BTC) “Spectre” Drop-in MOSFET
- Overview
- Externals modification
- Internals modification
- Installation Guide
- Final Thoughts and Upgradeability
Overview
The BTC “Spectre” is probably the most popular computerized MOSFET system for AEG’s these days. Initial reviews noted issues installing the unit in Classic Army version 2 gearboxes due to the slightly thicker (non Tokyo Marui standard) shell design.
When I asked Frank (BTC LLC) about installation in a KWA 2GX gearbox he mentioned he had heard of it, but wasn’t really sure of the results. So I wrote this install “guide” as an accompaniment to The Review.
Externals Modifications
The idea of the drop-in kit is to avoid having to modify the shell or other internals. The Spectre does its job and does not require any modification of the gearbox or the other internal components.
Internals Modification
Since the KWA 2GX gearbox differs in tolerances from a standard TM gearbox some modifications were required of the Spectre MOSFET to get it to sit correctly in the gearbox to trigger the cutoff switch and to sit low enough for the trigger to activate the trigger switch.
Basically the post that used to hold the cutoff lever is slightly bigger in diameter than a standard TM. The OEM trigger also sits slightly higher than the standard TM so the Spectre has to be slightly skewed at an angle to sit far enough up to allow the cutoff switch to actuate, but still allow the trigger switch to work as well. By simply filing the area around the cutoff lever hole you can gain enough clearance to fit the Spectre. The picture shows a more aggressive removal of material than required so it would show up well for the review.
BE CAREFUL IN REMOVING PCB MATERIAL
If you accidentally remove the wrong area or an extremely aggressive amount (an excessive amount) you run the risk of cutting the printed electrical connections. Honestly this is almost fool proof but I cannot emphasis caution and careful work.
Installation Guide
Honestly it’s pretty simple, the KWA 2GX shell does add an extra step that some people might not have to face, but for the purpose of this guide, we do.
1. Pretty simple here, take the rifle apart, and open up the gearbox.
2. Remove the following parts since you will not need them anymore:
- Old wiring harness: This includes the trigger contacts, trigger block, and return spring for the block (and in my case a MOSFET that works, it’s just a basic model I will no longer be using).
- Cutoff lever, screw, and spring from the selector plate side.
- Safety lever, screw and spring
- Gearbox shell screw from just in front of the trigger (BTC includes a replacement that is roughly 1-2mm longer to keep the selector plate from falling off since the safety lever and cutoff lever are no longer there to keep it in place).
The second picture compares the length of the BTC screw (top), the stock screw (middle) and a similar stock screw (bottom).
3. Follow the instructions in the section above (Internals Modification) to properly seat the Spectre MOSFET in the gearbox. I removed the upper PCB containing the TVS diodes and MOSFETS for pictures, but the installation can be done with it present.
Be sure to check the shim height of the Sector Gear so that it consistently and reliably depresses the cutoff switch. Once satisfied be sure to lube the sector gear with grease so that it reduces wear on the cutoff switch.
Also install the trigger and make sure that it makes proper contact with the trigger switch and fully depresses it.
4. Reinstall the rest of the internal parts that may have been removed, route the red, black, and gate wire CAREFULLY through the gearbox. I cannot stress how easy it can be to accidentally cut the insulation on the wires, this will more than likely short out the MOSFET and kill it. Lastly, simply close the gearbox and bolt it back together.
The instructions say you can remove the anti-reversal latch if desired. This is due to the “Dynamic Braking” the MOSFET is capable of (also known as Active Braking by some). The factory default is disabled so you will have to set the brake setting by trial and error. HOWEVER, removing the AR latch will not allow the piston precocking to be used since there would be nothing there to hold the gears and piston back.
Once the gearbox is closed and the screws are back in, it’s worth checking the selector plate to make sure it fully depresses these two switches. If neither are depressed the rifle is in “safe.” If the first (on the left) is depressed the rifle is in “selector position 1” (factory default is Semi). If both switches are depressed, the rifle is in “selector position 2” (factory default is Full Auto).
The manual recommends wrapping the arm of the selector plate in electrical tape if it does not fully depress the selector switch cutoffs. I had no issues with the KWA 2GX gearbox and a Guarder M4 selector plate. However, I had to add a couple layers of tape on a VFC SCAR selector plate to get it to work (the VFC plate is thinner than the Guarder/TM spec).
I personally prefer to check my electrical setups outside of the body first since it saves me assembly time. In this case I simply clamped down the motor, plugged everything in, and pulled the trigger. It works, so time to throw it back in the body and get to programming it.
The BTC Spectre includes a 4 page printed manual (2 pages back to back). The first page covers installation (the install really is quite simple and this guide should cover any other questions or give an idea of what it should look like when finished.) The second page covers the rubric of how to get the Spectre into programming mode (hold down the trigger and plug in the battery), make any changes (number of trigger pulls, and a specific number of trigger pulls to cycle through the options), and how to tell if the changes are saved (the motor will buzz four times), and when it’s safe to unplug (after motor finishes buzzing).
I setup my gearbox with medium active braking (3 trigger pulls + 3 more), safe-semi-semi w/precocking (7 trigger pulls + 1, 4 motor buzzes, 9 pulls + countless trial and error till the piston was in the best compressed position). And a few other safety settings (LIPO monitoring, fuse settings, etc), but you get the idea.
The third page contains a description of the features such as precocking, semi w/ramping, LIPO monitoring, etc. The last page simply has a few quick troubleshooting answers in case things don’t work, or suddenly stop working.
Final Thoughts and Upgradeability
I was honestly very impressed with the ease of install with the Spectre. Minus the somewhat odd specs of the KWA 2GX shell, everything went very smoothly. I think it’s always safe to assume that nothing is quite the “plug-and-play” people always advertize things as (not just the BTC Spectre), but all in all the Spectre is very simple to get on the field.
My only real complaint with the system is the loss of the unmovable trigger when in safe mode. Since you have to take out the safety bar to make room for the Spectre PCB the trigger can be freely pulled when the selector(s) are in safe mode. Due to the dual selector position switches the rifle will not fire no matter what, but it is still slightly disconcerting to some, and at least confusing to most.
© Copyright triggs 2014
PERFORM THESE MODS AT YOUR OWN RISK. TAL or myself are NOT responsible for any damages or malfunctions that may happen as a result of performing this mod.
PERFORM THESE MODS AT YOUR OWN RISK. TAL or myself are NOT responsible for any damages or malfunctions that may happen as a result of performing this mod.
Modifying a KWA 2GX gearbox for a Black Talon Concepts (BTC) “Spectre” Drop-in MOSFET
- Overview
- Externals modification
- Internals modification
- Installation Guide
- Final Thoughts and Upgradeability
Overview
The BTC “Spectre” is probably the most popular computerized MOSFET system for AEG’s these days. Initial reviews noted issues installing the unit in Classic Army version 2 gearboxes due to the slightly thicker (non Tokyo Marui standard) shell design.
When I asked Frank (BTC LLC) about installation in a KWA 2GX gearbox he mentioned he had heard of it, but wasn’t really sure of the results. So I wrote this install “guide” as an accompaniment to The Review.
Externals Modifications
The idea of the drop-in kit is to avoid having to modify the shell or other internals. The Spectre does its job and does not require any modification of the gearbox or the other internal components.
Internals Modification
Since the KWA 2GX gearbox differs in tolerances from a standard TM gearbox some modifications were required of the Spectre MOSFET to get it to sit correctly in the gearbox to trigger the cutoff switch and to sit low enough for the trigger to activate the trigger switch.
Basically the post that used to hold the cutoff lever is slightly bigger in diameter than a standard TM. The OEM trigger also sits slightly higher than the standard TM so the Spectre has to be slightly skewed at an angle to sit far enough up to allow the cutoff switch to actuate, but still allow the trigger switch to work as well. By simply filing the area around the cutoff lever hole you can gain enough clearance to fit the Spectre. The picture shows a more aggressive removal of material than required so it would show up well for the review.
BE CAREFUL IN REMOVING PCB MATERIAL
If you accidentally remove the wrong area or an extremely aggressive amount (an excessive amount) you run the risk of cutting the printed electrical connections. Honestly this is almost fool proof but I cannot emphasis caution and careful work.
Installation Guide
Honestly it’s pretty simple, the KWA 2GX shell does add an extra step that some people might not have to face, but for the purpose of this guide, we do.
1. Pretty simple here, take the rifle apart, and open up the gearbox.
2. Remove the following parts since you will not need them anymore:
- Old wiring harness: This includes the trigger contacts, trigger block, and return spring for the block (and in my case a MOSFET that works, it’s just a basic model I will no longer be using).
- Cutoff lever, screw, and spring from the selector plate side.
- Safety lever, screw and spring
- Gearbox shell screw from just in front of the trigger (BTC includes a replacement that is roughly 1-2mm longer to keep the selector plate from falling off since the safety lever and cutoff lever are no longer there to keep it in place).
The second picture compares the length of the BTC screw (top), the stock screw (middle) and a similar stock screw (bottom).
3. Follow the instructions in the section above (Internals Modification) to properly seat the Spectre MOSFET in the gearbox. I removed the upper PCB containing the TVS diodes and MOSFETS for pictures, but the installation can be done with it present.
Be sure to check the shim height of the Sector Gear so that it consistently and reliably depresses the cutoff switch. Once satisfied be sure to lube the sector gear with grease so that it reduces wear on the cutoff switch.
Also install the trigger and make sure that it makes proper contact with the trigger switch and fully depresses it.
4. Reinstall the rest of the internal parts that may have been removed, route the red, black, and gate wire CAREFULLY through the gearbox. I cannot stress how easy it can be to accidentally cut the insulation on the wires, this will more than likely short out the MOSFET and kill it. Lastly, simply close the gearbox and bolt it back together.
The instructions say you can remove the anti-reversal latch if desired. This is due to the “Dynamic Braking” the MOSFET is capable of (also known as Active Braking by some). The factory default is disabled so you will have to set the brake setting by trial and error. HOWEVER, removing the AR latch will not allow the piston precocking to be used since there would be nothing there to hold the gears and piston back.
Once the gearbox is closed and the screws are back in, it’s worth checking the selector plate to make sure it fully depresses these two switches. If neither are depressed the rifle is in “safe.” If the first (on the left) is depressed the rifle is in “selector position 1” (factory default is Semi). If both switches are depressed, the rifle is in “selector position 2” (factory default is Full Auto).
The manual recommends wrapping the arm of the selector plate in electrical tape if it does not fully depress the selector switch cutoffs. I had no issues with the KWA 2GX gearbox and a Guarder M4 selector plate. However, I had to add a couple layers of tape on a VFC SCAR selector plate to get it to work (the VFC plate is thinner than the Guarder/TM spec).
I personally prefer to check my electrical setups outside of the body first since it saves me assembly time. In this case I simply clamped down the motor, plugged everything in, and pulled the trigger. It works, so time to throw it back in the body and get to programming it.
The BTC Spectre includes a 4 page printed manual (2 pages back to back). The first page covers installation (the install really is quite simple and this guide should cover any other questions or give an idea of what it should look like when finished.) The second page covers the rubric of how to get the Spectre into programming mode (hold down the trigger and plug in the battery), make any changes (number of trigger pulls, and a specific number of trigger pulls to cycle through the options), and how to tell if the changes are saved (the motor will buzz four times), and when it’s safe to unplug (after motor finishes buzzing).
I setup my gearbox with medium active braking (3 trigger pulls + 3 more), safe-semi-semi w/precocking (7 trigger pulls + 1, 4 motor buzzes, 9 pulls + countless trial and error till the piston was in the best compressed position). And a few other safety settings (LIPO monitoring, fuse settings, etc), but you get the idea.
The third page contains a description of the features such as precocking, semi w/ramping, LIPO monitoring, etc. The last page simply has a few quick troubleshooting answers in case things don’t work, or suddenly stop working.
Final Thoughts and Upgradeability
I was honestly very impressed with the ease of install with the Spectre. Minus the somewhat odd specs of the KWA 2GX shell, everything went very smoothly. I think it’s always safe to assume that nothing is quite the “plug-and-play” people always advertize things as (not just the BTC Spectre), but all in all the Spectre is very simple to get on the field.
My only real complaint with the system is the loss of the unmovable trigger when in safe mode. Since you have to take out the safety bar to make room for the Spectre PCB the trigger can be freely pulled when the selector(s) are in safe mode. Due to the dual selector position switches the rifle will not fire no matter what, but it is still slightly disconcerting to some, and at least confusing to most.
© Copyright triggs 2014
PERFORM THESE MODS AT YOUR OWN RISK. TAL or myself are NOT responsible for any damages or malfunctions that may happen as a result of performing this mod.