[R-390] FL101 Rebuild (R390)

Barry n4buq at knology.net
Sat Oct 22 12:38:32 EDT 2022


After finding the connection between the input and output for the "A" connection was open in FL101 of my R390, I removed the filter, opened the lid (lots of fun there...), and found the problem.

Along with the ubiquitous wooden blocks and wax, I found that the connections for virtually all the capacitors were bad or going bad.  The caps in mine filter have three connections where the end points are the through connection and there's a center connection that serves as the third connection allowing the capacitor's ground connection.  Each capacitor was housed in its own cute little thick paper box - a rather unique configuration that I'd not seen anywhere else.

I'm not sure what caused it, but the endpoint connections were such that I could simply pull the wires away from the capacitor and the capacitor for the "A" connection was the worse of any of them.  I don't know if those are electrolytic and the electrolyte leaked (doubtful as they aren't really sealed) but something caused quite a bit of dark corrosion which had virtually destroyed the solder connections.

In any case, the inductors are still in great shape and I can rebuild it so a relatively happy ending for this once I get the necessary parts.  Anyone know the proper value to use for those caps?  The filter is stamped with FILTER TYPE 97JX56 and I wonder if those numbers indicate the inductance and capacitance value (e.g. possibly 56pF but that's just a guess).

Thanks,
Barry - N4BUQ


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