Airsoft Store Canada presents - Installing a Gate MOSFET

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Introduction

Lately we've been getting some emails regarding MOSFETs and how to install them.

In the Gate Electronics manuals, which can be found here, it refers to two types of installation methods.

The guide below outlines Method #1 - installing the MOSFET without replacing existing wires. I was installing a NanoAB, but the procedure is identical for a MERF3.2 and very similar for a PicoSSR. For PicoSSR guide, click here.

Tools Required

1. Soldering Iron (30W or 40W iron will do)
2. Solder (Get something with flux core)
3. Multimeter

Installation Procedure

Step 1: Figure out where you want to put your MOSFET. NanoAB and MERF3.2 are usually confined to inside buffer tubes or handguards due to their size. With the PicoSSR, I've managed to fit one inside the mechbox itself.

Step 2: Get to the trigger assembly. I'm assuming you know what you're doing if you're reading this. There's lots of guides out there on gun disassembly.

Step 3: Clean your trigger contacts and the trigger sled. Even after some minor use, electrical arcing will cause the contacts to pit. Using some 600 grit sandpaper, gently sand the contacts to remove all visible marks. In the image below, you can see distinct discolouration and carbon buildup on the trigger sled and one of the contacts.


Step 4: Desolder the red wire going to the battery and join it to the red wire going to the positive motor terminal. It doesn't really matter which wire gets desoldered, but doing it this way gives you more clearance for the trigger to move.


Step 5: Solder the signal wire to the other trigger contact which you had freed up in Step 4.

Step 6: Reassemble the trigger assembly into the mechbox and see if your wires are interfering with the trigger and the safety lever. Reposition and adjust if necessary. Once you are happy with the product, shrink wrap the exposed wires.


Step 7: With the NanoAB and MERF3.2, all you need to do is to plug in the Deans connector and the signal wire. For the PicoSSR, you will need to solder the negative wires and signal wire directly to the circuit board. Make sure the negative battery wire is connected to the contact patch with the transistor pins, and the negative motor wire is connected to the opposite contact patch. Orientation matters.

Testing Procedure

While it's possible to test with the trigger assembly installed in the mechbox, it can be a bit difficult unless you have a helper. I would just take it out.

Note: The battery SHOULD NOT be connected during this procedure. If you connected your battery and attempted this, you will start a fire somewhere.

Step 1: Switch your multimeter to measure Resistance. Short the two probes and see if it reads 0 ohms. If it doesn't, make a mental note of this number and add it to your readouts.

Step 2: Push the trigger sled in between the contacts. Touch one probe to the positive battery terminal and the other probe to the signal wire. The resistance should be less than 10 ohms. If it is greater than 10 ohms, clean your contacts and check your wiring. It may need to be replaced. When you're done, pull the sled back out.


Step 3: Touch one probe to the positive motor wire and the other probe to the negative motor wire. Your multimeter will display OL (overload), Open Circuit, or some really big resistance value (i.e. 20 MOhms). If it displays anything less, you have a short circuit. Double check your wiring for rips or tears in the insulation. If you're confident you don't have a short, give us a shout.


Step 4: Push your trigger sled into the two prongs so that there is contact. Make sure it stays there. Repeat the measurement for the two motor connectors. Again, it should read OL, Open Circuit, or 20 MOhms. If it doesn't, you have a short somewhere. If you're confident you don't have a short, give us a shout.

That's it folks. Once you've completed all the tests with the multimeter, plug everything in. The signal wire plugs into the top pin of the NanoAB and MERF 3.2.

With the MERF3.2, don't forget to program it first, or your gun will start shooting automatically the moment the battery is plugged in.

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Introduction

In the Gate Electronics manuals, which can be found here, it refers to two types of installation methods.

This section deals with the installation of a Gate PicoSSR using Method #1 as outlined in the manual.

Tools Required

1. Soldering Iron (30W or 40W iron will do)
2. Solder (Get something with flux core)
3. Multimeter

Installation Procedure

Note: Before starting read this entire guide first. Throughout your install, as soon as you solder one wire, check for shorts in your wiring before proceeding onto the next step.

Step 1: Using your multimeter, test the resistance of the two large contact patches of the PicoSSR. Your multimeter should read OL (Overload) or some extremely large resistance in the MegaOhm scale. If it does not, contact us immediately.


Step 2: Figure out where you want to put your MOSFET. In this guide, I'm hiding the PicoSSR right underneath the spring guide in a Version 2 mechbox. For those with King Arms or Systema shells, this won't work as that section of the mechbox is not milled out. VFC, Tokyo Marui, Lonex mechbox shell owners should have no issues.

Step 3: Get to the trigger assembly. I'm assuming you know what you're doing if
you're reading this. There's lots of guides out there on gun disassembly.


Step 4: Clean your trigger contacts and the trigger sled. Even after some minor use, electrical arcing will cause the contacts to pit. Using some 600 grit sandpaper, gently sand the contacts to remove all visible marks. In the image below, you can see distinct discolouration and carbon buildup on the trigger sled and one of the contacts.


Step 5: Desolder the red wire going to the battery and join it to the red wire going to the positive motor terminal. It doesn't really matter which wire gets desoldered, but doing it this way gives you more clearance for the trigger to move. Check the resistance of the connection. It should read 0.0 or 0.1 Ohms.


Step 6: Solder the signal wire to the other trigger contact which you had freed up in Step 5.


Step 7: Reassemble the trigger assembly into the mechbox and see if your wires are interfering with the trigger and the safety lever. Reposition and adjust if necessary. Once you are happy with the product, shrink wrap the exposed wires.


Step 8: We will now proceed to install the PicoSSR. To do so, we will need to splice the negative wire (black) and insert the PicoSSR into the splice. Measure out an appropriate length and make your cut. Solder the motor terminal end to the contact patch shown in the picture. DO NOT REVERSE THE ORIENTATION


Step 9: Measure out your thin gate wire to an appropriate length and solder it to the contact patch on the backside of the PicoSSR. In the picture, I have the gate wire running along the edge of the circuit board. DO NOT LET THE GATE WIRE TO SIT ON ANY COMPONENTS. The components get hot during operation and will melt the insulation and short circuit everything. This would burn out the PicoSSR. I specifically added some extra heat shrink to the gate wire to prevent this.


Step 10: With the motor negative lead and gate wire in place, you can proceed to heat shrink half of the circuit board. Leave the other contact patch exposed. The included heat shrink melts and forms a waterproof layer over the components. Make sure it doesn't cover the contact patch. If you have other heatshrink lying around, use that instead of the included stuff.


Step 11: Using your multimeter, it's time to test your wiring for shorts. Below is a comprehensive table of all checks. If your results deviate from the table, revisit your wiring and examine for any shorts.

Probe Point #1 - Probe Point #2 - Result

Positive Battery Terminal - Negative Battery Terminal - Overload
Positive Battery Terminal - Positive Motor Terminal - <1 Ohms
Positive Battery Terminal - Gate Terminal - Overload
Positive Battery Terminal - Gate Terminal with Trigger Pressed - <1 Ohms

Positive Motor Terminal - Negative Motor Terminal - Overload

Negative Battery Terminal - Positive Motor Terminal - Overload
Negative Battery Terminal - Negative Motor Terminal - Overload
Negative Battery Terminal - Positive Motor Terminal with Trigger Pressed - Overload
Negative Battery Terminal - Negative Motor Terminal with Trigger Pressed - Overload
Negative Battery Terminal - Gate Terminal - Overload
Negative Battery Terminal - Gate Terminal with Trigger Pressed - Overload

Negative Motor Terminal - Gate Terminal - Overload
Negative Motor Terminal - Gate Terminal with Trigger Pressed - Overload

Step 12: Bend the battery negative lead as shown in the picture and solder as shown.


Step 13: Test fit everything. Watch out for the piston.


Step 14: Apply heatshrink to cover the exposed half of the circuit board.


Step 15: On all mechboxes, there are posts sticking out of the top half. They are designed to keep the wiring in place. You will need to cut off these posts.



Step 16: As a final check, reassemble the two halves and grab your multimeter. Run those checks again. Any deviation from the results listed below warrants a revisit of your wiring.

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PicoSSR Installation Guide completed. Let me know if you guys have any questions.