Chamberlain B970 garage door opener

[DarkKnight]

Hi everyone!

Chamberlain B970 garage door opener reverses mid-cycle, even though the photo-eye sensors appear aligned and clean. Could something be affecting the sensor’s functionality?

[TinyTool]

Ah, this is a common and frustrating issue with garage door openers! Several things could be causing the B970 to reverse mid-cycle, even when the photo eyes look fine on the surface.

First, check if there's any subtle misalignment - sometimes the eyes can look aligned but be slightly off. Try this quick test: place a piece of cardboard in front of each sensor. If the LED lights change on both sensors, they're detecting correctly. If not, you might need some fine-tuning of their position.

Another sneaky culprit could be loose wiring connections at either the sensors or the opener unit itself. Over time, vibration from the door operation can gradually loosen these connections. I'd check both ends of the sensor wires to make sure they're securely fastened.

Also, believe it or not, bright sunlight can sometimes interfere with the sensors, especially during certain times of day. If you notice this happening more at specific times, you might want to install small hoods over the sensors to shield them from direct sunlight.

If none of these solve it, the force adjustment settings might need tweaking. The B970 model has sensitivity settings that can sometimes get thrown off, causing it to think it's hit an obstacle when it hasn't.

[DarkKnight]

Thanks for the tips! The alignment and wiring seem fine. Could it be an issue with the opener’s motor or the control board? I’ve heard these can sometimes cause problems like this too. Any advice on how to check those parts?

[TinyTool]

Glad the alignment and wiring are all good! It could definitely be the motor or the control board causing the problem. Here’s how you can check:

Motor: Listen for any weird sounds like grinding or buzzing when the opener runs. If it stops working after running for a bit, it might be overheating. You can also disconnect the garage door (pull the emergency release cord) and run the motor alone. If it works fine without the door, the issue might be the door’s weight or unbalanced springs.

Control Board: Take a look at the board itself—are there any burn marks, loose connections, or corrosion? Also, check if the opener has any diagnostic lights flashing a code (your manual should explain them). A quick reset—unplugging it for a few minutes—might clear up a glitch, too.

If you’ve got a multimeter, you can check if the motor is getting the right voltage. Sometimes it’s just a worn-out capacitor that needs replacing. But if the motor is failing, replacing the whole opener might be the better option.

Let me know how it goes!

[DarkKnight]

Thanks for the help so far TT! I’m wondering if the issue could be with the capacitor. If the motor runs for a while and then stops, could it be a sign that the capacitor is failing? How would I test the capacitor using a multimeter to check if it’s the culprit? Also, could a malfunctioning control board cause intermittent operation like this?

[TinyTool]

You are welcome! If the motor runs for a while and then stops, a failing capacitor could absolutely be the issue. The capacitor provides the initial surge of energy needed to start the motor and helps maintain torque. When it begins to fail, the motor might struggle or stop intermittently.

To test the capacitor with a multimeter:
1. Turn off the power to the opener and unplug it to ensure safety.
2. Discharge the capacitor by touching its terminals with an insulated screwdriver.
3. Set your multimeter to capacitance mode (marked as "μF").
4. Connect the probes to the capacitor terminals and compare the reading to the printed value on the capacitor (e.g., 40 μF). If the reading is significantly lower, it’s likely defective and needs replacing.

As for the control board, it can definitely cause intermittent operation if there’s a fault. Common issues include:
- Loose solder joints
- Aging relays
- Corrosion on the board
- Voltage fluctuations

The Chamberlain B970 has diagnostic lights near the "Learn" button that can provide error codes to help narrow things down. Check the flashing pattern and refer to the manual or Chamberlain’s support site to interpret the code.

If there are no clear signs from the capacitor or the diagnostics, it might also be worth inspecting the motor's thermal protection system. Sometimes, if the motor overheats, it shuts down temporarily until it cools.

[DarkKnight]

The Chamberlain B970 has diagnostic lights near the "Learn" button that can provide error codes to help narrow things down. Check the flashing pattern and refer to the manual or Chamberlain’s support site to interpret the code.

Oh, thanks for the information! That’s really helpful.