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Saturday, June 7, 2014

Beomaster 8000: Occasionally Missing Display Segments - PCB #8 Rebuild

Today I worked on the display PCB (#8) of the Beomaster 8000 that I am currently restoring. While I worked on the power supply board I noticed that the display segments flickered occasionally when touching the display board. The contacts between the processor board (#9) and the display board is really one of the weaker points of the 8000 internal design (no weak points on the outside, in my opinion!) and prone to issues. So I took the display board off and cleaned the contacts with a fiberglass pen and then coated them with DeoxiT D100. I also bent every second pin of the headers slightly to increase the pressure between the male and female contacts. This usually does the trick. Here is a pic of the contacts - it really does not take much bending:

I also replaced the two electrolytic capacitors on the board (there are only two - I'll let you find them...;-).


And after:

Detail (C7):

After I put the board back in, wiggling it would not produce missing segments anymore...hopefully this is now stable!

It is noteworthy that this display board features fiberglass PCBs for the volume, input and frequency displays - note the green color on the display in the upper right corner of the photo - previously, I only saw these boards used for the balance display, and these usually then had no missing segments. Maybe this explains that this Beomaster has not had display issues so far.

On to the inner sanctum, the processor board (#9)...problematic vias may need some attention there!

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