My synrad J48 died , way out of warranty (2006 tube) so we decided to open it . got a shock when I saw some components had desoldered themselves.on both the RF boards.
One resistor looks fried .
We gonna try repair by just checking the desoldered components and resoldering them.
Must have had a lot of heat - not sure why this happened , but the board and other stuff don't look damaged...
Here are some pics
a copy of the circuit diagram is to be found on PAGE 18 of this PDF
http://www.synrad.com/Manuals/j48v54.pdf