Blooy BC-LBH790-NBL Bobbin Case Instruction Manual

Introduction

This manual provides instructions for the proper installation, operation, and maintenance of the Blooy BC-LBH790-NBL Bobbin Case. This bobbin case is designed for compatibility with various electronic buttonhole sewing machines, including JUKI LBH-1790, 790, 791S, 1700, JACK T1790, and Zoje 1790 models, as well as many other brand 1790 electronic buttonhole sewing machines.

Please read this manual thoroughly before using the product to ensure safe and efficient operation.

Product Overview

Figure 1: Top-down view of the Blooy BC-LBH790-NBL Bobbin Case. This image shows the overall shape and the latch mechanism.

The Blooy BC-LBH790-NBL is a replacement bobbin case, essential for the proper functioning of compatible electronic buttonhole sewing machines. It holds the bobbin and regulates the lower thread tension.

• Part Number: BC-LBH790-NBL
• Alternate Part Number: 137-29769
• Compatibility: JUKI LBH-1790, 790, 791S, 1700; JACK T1790; Zoje 1790; and other 1790 series electronic buttonhole sewing machines.

Setup and Installation

Before installing the new bobbin case, ensure your sewing machine is turned off and unplugged from the power source to prevent accidental operation.

1. Remove the old bobbin case: Open the bobbin compartment cover on your sewing machine. Carefully remove the existing bobbin case. Refer to your sewing machine's specific manual for detailed instructions on accessing and removing the bobbin case.
2. Inspect the new bobbin case: Examine the Blooy BC-LBH790-NBL bobbin case for any visible damage or defects.


Figure 2: Side view of the bobbin case, highlighting the tension spring and latch mechanism. Ensure these components are intact.

3. Insert the bobbin: Place a wound bobbin into the new Blooy BC-LBH790-NBL bobbin case. Ensure the thread unwinds in the correct direction as specified by your sewing machine's manual.
4. Thread the bobbin case: Guide the bobbin thread through the tension spring of the bobbin case. The thread should pass smoothly under the tension spring.


Figure 3: Internal view of the bobbin case, showing the central pin and the path for the bobbin thread under the tension spring.

5. Install the new bobbin case: Hold the bobbin case by its latch and carefully insert it into the bobbin compartment of your sewing machine. It should click securely into place. Gently tug on the bobbin thread to confirm it is properly seated and tensioned.


Figure 4: The bobbin case with its latch open, ready for insertion or removal from the sewing machine.

6. Close the compartment: Close the bobbin compartment cover.

Operating Instructions

Once the bobbin case is correctly installed and threaded, you can resume normal sewing operations. The bobbin case is a passive component that holds the bobbin and provides tension to the lower thread. Its proper function is critical for balanced stitches.

• Thread Tension: The tension of the bobbin thread is primarily controlled by the small screw on the bobbin case's tension spring. For most applications, the factory setting is sufficient. If you experience unbalanced stitches (top thread showing on the bottom or vice-versa), adjust the upper thread tension on your sewing machine first. Only adjust the bobbin case tension screw as a last resort, making very small adjustments (quarter turns) at a time.
• Bobbin Winding: Always use bobbins specifically designed for your sewing machine model and wind them evenly. An unevenly wound bobbin can cause thread jams and inconsistent tension within the bobbin case.

Maintenance

Regular maintenance of your bobbin case ensures smooth operation and extends its lifespan.

• Cleaning: Periodically remove the bobbin case and clean it thoroughly. Use a small brush or lint remover to clear any lint, dust, or broken thread fragments that may accumulate around the tension spring and inside the case. Accumulation can affect thread tension and cause stitching problems.
• Inspection: Regularly inspect the bobbin case for wear, especially the tension spring and the edges where the thread passes. A worn or damaged bobbin case can lead to skipped stitches, thread breakage, or uneven tension.
• Lubrication: The bobbin case itself typically does not require lubrication. Refer to your sewing machine's manual for lubrication points within the bobbin area of the machine.

Troubleshooting

If you encounter issues related to the bobbin thread, consider the following troubleshooting steps:

• Thread Breakage:
  • Ensure the bobbin is correctly inserted and threaded through the tension spring.
  • Check for burrs or rough spots on the bobbin case that might be snagging the thread.
  • Verify the bobbin is wound evenly and not overfilled.
  • Confirm the correct bobbin size and type for your machine.
• Uneven Stitches / Looping:
  • Re-thread the bobbin case, ensuring the thread is properly seated under the tension spring.
  • Clean any lint or debris from the tension spring area.
  • Adjust the upper thread tension on your sewing machine.
  • If necessary, make very minor adjustments to the bobbin case tension screw.
• Bobbin Jams:
  • Ensure the bobbin case is fully seated and locked into position.
  • Check for any loose threads or fabric scraps in the bobbin area.
  • Verify the bobbin is not overfilled or unevenly wound.

If problems persist, consult your sewing machine's specific instruction manual or contact a qualified service technician.

Specifications

Warranty and Support

For information regarding warranty coverage or technical support for your Blooy BC-LBH790-NBL Bobbin Case, please refer to the retailer where the product was purchased or visit the official Blooy website. Keep your purchase receipt as proof of purchase.