[R-390] R-390 power issues tips

[Frank Hughes]

Hi Tom,
Glad you are trying to get another R-390 working!

The folks on the list helped me get a Hamfest basket case working, mine had
many problems, but the first one to solve was that the 3/8A fuse would not
remain intact.
Here are some notes I cut and pasted:

"The Hamfest R390 did not work,( B+ was over 300vdc).

R626 had drifted WAY up, replaced it to restore regulation.

3/8A fuse kept blowing, turned out that there was a shorted 26Z5W.

Some resistors in the power supply were smoking.

Replaced the resistors R801-R804 with the suggested wirewounds.

Replaced the power supply CR801 w/ a modern full-wave bridge rectifier."



Note I later learned that replacing the resistors in the PS with wirewounds
was not a good idea, as these are sacrificial, and are supposed to open
before the transformer windings, so as to protect them.
By installing wirewound 4W units, I just made the transformer windings the
fuse.

The list does not support photos, but here are the links to some other info
that the folks here sent me to help:


http://i180.photobucket.com/albums/x257/fish1_07/R-390/R390%203-8%20fuse_zpshh0h7vux.jpg
http://i180.photobucket.com/albums/x257/fish1_07/R-390/R390RegulatorCircuitry_zpsa4wkxeud.jpg

73
Frank
KJ4OLL