Step-by-Step Guide
Understanding Why Fuses Blow
Before replacing blown fuses, it's important to understand the root cause. Blown fuses are almost always related to field wiring issues, not the controller itself.
A fuse is designed as a weak point in a wire path that will burn out before other devices are damaged. For example, if you have a 2 amp fuse, the wire might be rated to handle 3 or 5 amps, but if current exceeds 2 amps, the fuse will burn out first. This protects the more expensive components in your system. The proper response is to remedy the underlying problem, not simply install a bigger or better fuse.
Common Causes of Blown Fuses
Field wiring issues that cause blown fuses include:
- Overcurrent on two-wire systems: This can be a precursor to more serious overcurrent issues. Excessive current flows across the wire path, often caused by a black and red wire touching or a faulty device. The problem may be intermittent, so you might experience fuse issues even without consistent overcurrent problems.
- Excessive draw on conventional wire paths: While less common, this can also cause fuses to blow.
The speed at which a fuse blows indicates the severity of the problem:
- Instantaneous blow: If the fuse pops immediately when you install it and turn the system back on, this indicates a very high current draw.
- Delayed blow: If the fuse takes time to blow (possibly a day or more), this indicates a medium or lower current draw.
Locating Fuses in a BaseStation 3200
The location and number of fuses in your controller depends on whether you have a two-wire system or a conventional wire system.
1. Open the controller cabinet to access the internal boards.
2. Locate the power board, which is mounted on the side of the controller.
3. Remove the cover on the power board to reveal a slow blow fuse.
4. If you have a two-wire system, locate the 2R board. There are additional fuses underneath this board and one slow blow fuse clipped to the back of the board.
All fuses in the controller are marked with text that says "replacement fuse contact support before use." This reminder indicates that you should resolve the underlying field wiring problem before simply replacing fuses repeatedly.
Inspecting Fuses on the Power Board
1. Examine the slow blow fuse on the power board. Note that when the power board is mounted in the controller, it will be positioned vertically, making the fuse slightly harder to see.
2. Look for visible signs of damage. Sometimes you can tell if a fuse is burned by visual inspection.
3. If visual inspection is inconclusive, remove the fuse and use an ohm meter to test both sides of the fuse to determine if it's good.
Inspecting Fuses on a Two-Wire System
1. Separate the power board and two-wire board by pulling them apart at the connection pins.
2. Remove the cover from the two-wire board.
3. Locate the two fast blow fuses inside. A spare fuse is also included with the board.
4. Inspect both fuses. If either fuse is blown, it will prevent power from reaching your two-wire path, which is one of the symptoms you might observe in the field.
Inspecting Fuses on a Conventional Wire System (R Board)
1. Remove the screws securing the plexiglass cover on the R board.
2. Lift off the cover to reveal a slow blow fuse.
⚠️Note that blown fuses are less common on conventional wire systems compared to two-wire systems.
Troubleshooting a Blown Fuse
1. Replace the blown fuse with a new one of the correct type (slow blow or fast blow, depending on the location).
2. Disconnect the field wire path before powering the system back on. This isolates the controller from the field wiring.
3. Power on the system and observe whether the new fuse blows:
- If the fuse does not blow with the field wire disconnected, the problem is in your field wiring, not the controller board.
- If you reconnect the field wire and the fuse blows again, this confirms the issue is in the field wiring.
4. Investigate the field wiring for miswiring or poor wire integrity that needs to be resolved.
Fuse Specifications and Testing
The fuses used in HydroPoint controllers are standard automotive fuses. You can purchase the appropriate slow blow or fast blow fuses as replacements—there is nothing particularly specialized about them. However, the goal is to contact support to troubleshoot the wire path issue rather than repeatedly replacing fuses without addressing the root cause.
If you're unsure whether a fuse is blown, you may need to use an ohm meter to test it. If you're unfamiliar with using an ohm meter or volt-ohm meter, tutorials are available online and in the Baseline web training resources.
Warning Signs of Ongoing Wiring Problems
Certain conditions indicate a persistent field wiring problem that requires immediate attention:
- Missing fuse: If a fuse is missing from its holder, this means it has been used as a replacement for a blown fuse.
- Box of replacement fuses: If you find a small box of replacement fuses at the site, this indicates that the one or two fuses originally included with the controller were not enough, and additional fuses had to be purchased.
These signs clearly indicate that the problem is not with the controller but with the field wiring. There is either a miswire or poor wire integrity that must be resolved. When these conditions are observed, stop replacing fuses and focus on diagnosing and repairing the wiring issue.
Video Walkthrough
Video originally published January 2021.
If you have questions, here are 3 ways to get answers:
1. Search within this HydroPoint knowledgebase
2. Visit the HydroPoint support page
3. Call 800-362-8774 or email support@hydropoint.com, hours are Mon-Fri 3:00 AM – 6:00 PM PT and Sat 9:00 AM – 2:00 PM PT.