Does your light put out the same brightness on both high and low? If so, it could be a switching problem, and we can send you a new switch. If not, you may have purchased defective or inferior bulbs. We find that the quality of bulbs vary from batch to batch. When we purchase our bulbs, we do random testing from the batch for brightness and quality, and have had to return entire batches at times.
Here are some things to try:
Try Another Bulb
To eliminate any possibility of it being a bulb problem, I would suggest swapping bulbs with another light. The reason for doing those things is that we want to be 100% sure that it can’t be a supply problem or a bulb problem before going further.
Check the Circuit
There may be high resistance somewhere in the circuit to the light. With resistance in the circuit, if you measure the voltage it will show normal until a load is put on the circuit. The more the load, the more voltage drop and the lower the voltage at the light. Use a multimeter to measure the voltage at the light (with the light connected, touch the test leads to the bare wires) with the light turned off, then on. You will probably find that the voltage drops dramatically when the light is turned on. That indicates high resistance somewhere between the breaker and the light location.
The most common cause that we have seen for this is a crimp-on terminal accidentally being crimped on the insulation rather than the stripped bare wire. It can pierce the insulation just enough to barely make contact. It sometimes will work okay initially, then fail later. The red works because it uses very little power, so the voltage drop is low. The red night vision is hooked up to the main power wire before it goes into the ballast, and draws much lower power – .10 amp, as opposed to the white on high (.85 amp) and .40 amp on low power. As soon as you turn the white on, the load is about 20 times higher, so the voltage drop is also that much higher.
It Might Be the Rocker Switch or Power Supply
Check the voltage at the rocker switch. When you test the voltage at the switch, have the light turned on. A high resistance in the wiring will not show up as a voltage drop unless there is a load on the circuit. Alternatively, you could remove the light and any crimp-on terminals and touch the leads directly to a battery to eliminate any possibility of it being a power supply problem. We have seen high resistance many times from crimp-on terminals when it was inadvertently crimped mostly on the insulation. It works for a while — sometimes for years — before showing up.
Check the Capacitor
Another test you can try if the above things prove it to not be supply or bulb is this: Locate the orange capacitor soldered to the back of the switch. Does it look fine, or burned up? If burned up, we need to replace the capacitor. To test the capacitor if not burned up, with the light turned on, use a screwdriver to short together the two terminals that it is soldered to, and see if it goes brighter. You must use a screwdriver with an insulated handle and be careful not to touch the shank. Those terminals carry high-voltage which can give a very nasty shock.
It’s Rarely the Ballast but…
It is possible that it could be a ballast problem, but usually if the ballast fails, it fails completely. In over 23,000 lights, we have seen less than a half-dozen ballasts fail, but still provide some power. It is worth a little investigation before going to the trouble of replacing the ballast. If you have a digital amp meter in your system and can determine the actual power consumption (by comparing system amps with the light on vs. off), that would tell if the ballast is operating at the correct level.
Alternatively, if you have a decent digital multimeter, you can disconnect the light and measure the amps directly with the meter. If the amp draw on high is around .75 amp to .9 amp, then the ballast is likely okay. It’s best to allow a couple minutes of warm-up time before reading the amps. On rare occasions we have seen a ballast’s output drop to about half of normal, but that is a defect and is not an age-related thing (and the power consumption also drops). It would be a shame for someone to go to the trouble of replacing a ballast for nothing.
Bulbs are always the prime suspect, and it’s possible that you have a substandard replacement bulb. Probably the best test before going to the trouble of replacing a ballast would be to swap bulbs with the newer light that appears brighter, and see if the ‘dim’ problem moves with the bulb, or stays with the older light.