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Thursday, November 10, 2016

Beomaster 8000: Step Five (2) - Rebuilding the Displays and Indicator Lights with SMD LEDs

After 24 hours the LEDs were all still in business, and so I decided to put the displays back together. My current method is to press the display covers onto the PCBs with carpenter clamps and then use black hot glue to seal the sides of the display units. This keeps them together reliably, while it is still reversible - with some effort the glue can be peeled off to open them again. I like solutions like this since no one (and no electronic component) is 100% perfect, and so it is nice if one can repair things (again) at a later date if necessary.

After putting the displays back together I usually run them for another 24 hours to make sure that the assembly process did not inflict damages on the SMD LEDs:
While this test was running, I did the rest of the display PCB. I replaced the two electrolytic capacitors with 105C grade Japanese units and then I went on to replace the four incandescent light bulbs that illuminate the indicators (clipping, filters, mono, and manual tuning). This shows the right two bulbs in their reflector boxes:
The original bulbs usually have very weak leads since they corrode over time. The slightest motion of the bulbs can break them off. Therefore, I developed a SMD LED based solution to replace them. This shows them in place of the bulbs with the reflector box removed:
There need to be two versions of these SMD LED boards since the reflector cases are mirrored for the left side, i.e. the polarity is reversed (which plays a role for LEDs while bulbs are impervious to the current direction): 
And here with the reflectors put in place:
After the 24 hrs test I soldered the displays back into the PCB:
Before I test this board in situ I will restore the microcontroller board...more about this in the next post of this project.

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