The solenoid of a paintball marker is the physical connection between the electronics that fire the marker, and the pneumatics that do the actual firing operation. The solenoid is an electromagnet-based valve that is used to switch airflow within the marker, simultaneously pressurizing and depressurizing different parts to actuate the valve system. Every electronic marker uses a solenoid, although there are many differences in some of the valves used in other applications.
The solenoid in the Shocker is located attached to the underside of the body, within the grip frame.
Solenoid Operation:
The purpose of the solenoid is to take in pressurized air and output it into one of two possibly ports. This makes the solenoid in the Nerve a four-way valve, meaning it has two inputs and two outputs. The output air is shunted into the piston housing, where it will push the ram in one direction (either forward or back).
To recap the Nerve's firing cycle, while the marker rests idle pressure is forced into the front of the ram housing, to push and hold the ram/bolt open. This air is directed there through the solenoid valve. When the trigger is pulled and the solenoid energized, the solenoid's valve switches positions and the air holding the ram/bolt open is vented, while at the same time pressure is delivered to the rear of the ram housing, which forces the ram to move forward. Once it reaches the full forward position, the valve is opened and air pressure is released to fire the paintball. After the dwell time expires, the solenoid will switch back to the idle position by venting the air holding the ram/bolt closed and repressurizing the other output (to open the ram/bolt). After this time, the marker is ready to fire once more.
If you wish to learn more about how the solenoid works, please refer to the How solenoids work link in the Related Links section. Detailed information and diagrams can be found there.
Solenoid Types:
Currently there are two solenoids directly compatible with the Shocker and Nerve. Markers assembled before approximately December 2004 have the Parker K4H03 solenoid, whereas later markers have the Humphrey CRCB-0045W solenoid. These dates are only approximate, since assembly schedules are impossible to predict and vary from gun to gun. Please check your solenoid if you are unsure which you have:
The Humphrey valve offers increased flow and better overall reliability (thanks to a better manufacturing process). Additionally, the upper circuit boards are removable from the Humphrey valves. With the Parker solenoids the board must be desoldered and this is the cause for some problems (see the below section Connection). Parker solenoids feature a different spool design, which allows them to operate at lower dwell times and cycle faster overall. There isn't one general "better" solenoid; they clearly have their own advantages and disadvantages (as just explained). For that reason, there is almost never cause to "upgrade" from the old Parker to the newer Humphrey. The solenoid doesn't play that important of a role to the point where it would make any noticeable difference...so just keep your Parker valves in your guns until such time that they require replacement.
It is true that the Parker K4H01 solenoids from the Impulse and pre-03 Shocker will functionally work in a Nerve and 2003+ Shocker. However, the circuit board won't attach to the top of one of these solenoids (they're designed to attach with wires leading to the board, not the board itself). It is true that they can be modified to fit, however this isn't a modifiction I suggest you perform unless you have the right equipment. The solenoid terminals are very fragile and easy to destroy in the process.
Solenoid/Upper Board Connection: 
The relation of the solenoids with the upper board is simple in this regard. The upper board is removable with the newer Humphrey solenoids, but NOT removable with the older Parkers. With the Parker solenoids, the two coil terminals stick up out of the coil housing, and are soldered directly to the board. The board therefore cannot be removed unless it is desoldered from the solenoid terminals. I personally do not recommend doing this for any reason, unless you are absolutely forced to do so. I recommend this soldering task only for advanced technicians, since desoldering the solenoid is a very delicate operation and the coil terminals are extremely fragile.
Solenoid Manifold:
The solenoid is screwed onto the body of the Nerve at the spool housing end; this is the end where airflow is exchanged between the Nerve and the solenoid. Located between the solenoid and the Nerve body is a metal plate known as the solenoid manifold, which supports and aligns the necessary seals that are required to maintain the air exchange between them. Specifically, the manifold houses six small o-rings, which are used to seal the input and outputs. This diagram shows the o-ring grooves and the o-rings that fit inside:
The manifold accepts the above sizes of metric o-rings to seal its o-ring grooves. Please note that the 1x3-mm o-rings are regular "circular" o-rings that simply are fitted into an ovular groove. When installed they will appear ovular, however they're just regular o-rings to begin with.
Please note that the tapered side of the manifold faces toward the front of the marker. The marker will leak if installed backwards.
Although the Shocker SFT also uses a solenoid manifold, Shocker and Nerve manifolds are not interchangeable.
Nerve uses shorter manifold screws than the Shocker, to hold the manifold to the body. Shockers ues 1/4" screwed whereas Nerves use 5/32" ones.
Solenoid "body gaskets" from Impulses and pre-2003 Shockers will not work with a Nerve solenoid.
Solenoid Manifold Mounting:
The solenoid manifold is secured onto the Nerve body using a pair of 4-40 x 1/4" button head screws, which accept a 1/16" allen wrench for removal. The solenoid itself is attached to the top of the manifold using a pair of specialty spacer screws, which will also accept a 1/16" allen for removal, however can't be purchased at a local store. The spacer screws have a tall head to help support the upper circuit board.
Also please refer to the manual scan in the Related Links section, which has a nice exploded diagram of the manifold and its screws.
When reinstalling solenoid spacer screws, DO NOT overtighten them into the manifold. The threads are very fine and will happily strip themselves out if you simply torque the screws down as hard as you can. Overtightening screws in the marker is never a good idea, and will be extremely easy to cause damage in this case. A stripped solenoid manifold can only be repaired by replacement.
Many people simply prefer to leave the spool housing section of the solenoid attached to the manifold, and remove it only when absolutely necessary. Ideally your solenoid manifold won't be able to strip itself out if you never actually screw the screws down into it (as in, if you never have the chance to strip the manifold out, it won't become stripped, thus solving the problem). For troubleshooting it may be necessary to remove the solenoid, but otherwise I tend to agree with this philosophy.
Aftermarket Solenoid Manifolds:
New Designz offers a stainless steel manifold which is much more difficult to strip than the aluminum stock part. This new manifold also offers ball-rounded exchange grooves to help increase airflow and venting. Available for approx $30.
Overview:
· The solenoid is a pneumatic valve that switches airflow within the marker, when energized by electricity from the circuit board.
· Older markers came with Parker solenoids, newer ones come with Humphrey solenoids.
· Parker solenoids are NOT removable from the circuit board. Humphrey solenoids are.
· The solenoid manifold is a mounting plate between the solenoid and the body; it houses o-rings that seal the solenoid pressures.
· The solenoid manifold is easily stripped by overtightening.
Related Links:
· Shocker solenoid assembly manual scan
· Shocker leak troubleshooting
· Solenoid maintenance
· How solenoids work
· Upper circuit board
