Setting up the Beosystem display board rework station took a bit longer than anticipated, but it’s finally ready for LED display repairs and testing. A working Beocord display helped confirm the test setup’s functionality.
The display board, with its front and back sides visible, now features markings indicating segment numbers and polarities.
Thirty-one LEDs comprise the display. The image provides a close-up view of the original LED lights.
Here, the original LED is juxtaposed with the replacement SMD LED.
To ready the board for the new SMD LEDs, the old LEDs are scraped off using a razor blade. Removing the small pads on which the old LEDs sit improves the soldering of the SMD LEDs.
This creates the perfect space for the new LED. A reel of Lumex SML-LX06031W-TR LEDs was purchased to service the numerous Beosystem displays awaiting repair.
The small size of the LEDs necessitates magnification and specialized SMD tweezers. Images show the top and bottom of the Lumex SMD LEDs.
A magnifying glass is needed to see the cathode mark. Each LED is inspected individually while being held with tweezers. Despite being uniformly oriented in the reel, double-checking ensures correct placement.
For single board repairs, holding the LED with tweezers and soldering with a fine-tipped iron suffices. However, with multiple displays and 62 solder points on this Beocord display alone, an SMD rework station is more efficient.
An Aoyue SMD rework station is used.
The 853A preheats the board to around 180˚C, reducing the heat gun’s exposure time. Subsequently, the 968A station’s heat gun, set to 340˚C with minimal airflow, prevents SMD component displacement.
The Beocord display board is depicted before and after the heating station treatment.
After cleaning with isopropyl alcohol, magnified inspection, and continuity checks with a DMM, three faulty board traces were identified and repaired using thin magnet wire.
Finally, the board test was successful.
The display board will remain powered on overnight in the test setup. The following day, it should be ready for reassembly and reinstallation into the Beocord, leaving only a few minor tasks to complete the project.