There are a variety of sprinkler repairs that can be handled by the homeowner and which will save you money on sprinkler repairs.
Some of the most common sprinkler repairs are fixing clogged heads, replacing broken fittings, adjusting water volume and pressure at the sprinkler valve and dialling in the directional spray pattern and volume control at each spray nozzle. Other instances include replacing a malfunctioning solenoid or worn out sprinkler valve, setting an automatic sprinkler timer for proper operation, or replacing a sprinkler control box and properly labelling each zone for connecting the control wires to each valve solenoid.
Before making repairs to a sprinkler system, it is always a good idea to perform a pressure check on the sprinkler supply line. If the pressure is excessive (over 70 PSI), your system will be hard to dial in for proper volume and pressure spray patterns. The pressure is so high that the range of the volume control of each sprinkler valve zone becomes very narrow and when trying to dial in the spray pattern at each head, the screw that controls the volume control must be turned almost all the way off to control the spray range. When this occurs, the water coming out is under such pressure it becomes a mist and is termed atomising. The water is not coming out in large droplets but rather a mist and does not penetrate the ground well and a lot of the water is evaporated in the air before reaching the ground. Ground saturation becomes poor in this situation. You can live with a subpar system, or you can install a pressure regulator inside a yard box located in the ground somewhere inline to the sprinkler valve manifold. Set the pressure for 60 PSI, and you will be able to dial in the proper volume settings on each sprinkler valve enabling the proper adjustment range on each sprinkler head to satisfy range requirements.
Now that you have control over your sprinkler system lets look at the height of the sprinkler control valves. They should be at least 6 inches above the highest sprinkler head while that head is raised and in the on position. This will extend the life of your valves while satisfying local plumbing code for backflow prevention practices.
How to fix a clogged sprinkler head
Run the system for each zone manually using the small standard screwdriver and turn the bleed screw counterclockwise about a 1/4 turn. This should momentarily turn on the sprinkler valve for the zone you want to check. Identify which heads are not performing correctly. Attach a pair of vice grips on the shaft of the raised head and turn the system back off at the bleeder screw. The vice grips will keep the shaft suspended in the air and allow you to remove the head counterclockwise using a pair of pliers. This is usually a plastic threaded insert with an adjustment screw on the inside and an adjustment slot on the topside. Gently unscrew the adjustment part from the shaft and place it aside in a small bucket. Gently remove the plastic strainer resting inside the shaft and spray clean it under flowing water from your garden hose. Reinsert the filter back into the shaft. Replace the adjustment cap back onto the threaded shaft. Turn on the water at the valve bleed screw and test the sprinkler head. If it is still low, try adjusting the flow at the head using a tiny slotted standard screwdriver. If this makes no difference, replace the head. Make sure you buy the same spray pattern insert. 1/4, 1/2 or full pattern. Just take the old part with you and compare the orifice size and shape. The 1/4 stands for 90-degree spray pattern, the 1/2 stands for 180-degree spray pattern and the full stand for 360-degree spray pattern.
If the zone shows all of the sprinklers running at really high spray volumes and extending past where you want coverage, try reducing the volume at the zone sprinkler valve in question. Rotate the knob next to the bleeder screw clockwise to reduce volume until you see the sprinkler head shaft begin to lower back into the sprinkler head housings. Now turn it back up a little bit until they hold steady. Now you can adjust your individual spray head volume control settings at each sprinkler head until you have a satisfactory coverage pattern. It is important to note that without a pressure regulator controlling the max pressure entering the sprinkler valves, you may notice differences in your patterns during peak water usage times. Sometimes the flow will be higher or lower depending on street pressure. So I recommend a pressure regulated irrigation supply line be used to properly set up your initial volume and spray pattern settings at both the valves and the sprinkler heads.