It is amazing how many times I've found this to exist and how many times
that I've written about this on various reflectors. The power coat
paint on the chassis makes for an excellent insulator.
If you have an Astron power supply and you have not checked to see that
third pin ground is electrically connected to the chassis, or you have
not checked to see that he outer shell is connected to the bottom shell,
both being insulated by paint..........shame on you.
This applies to all Aston supplies, both linear and switching. Remove
the cover, remove the ground terminal where the green wire is attached,
scrape away the paint, place an internal tooth lock washer between the
terminal and chassis and reinstall the screw and nut. As to the shell,
using 100# sandpaper, sand away the paint on the inside for an area
about the size of a dime on both pieces, being the shell and pan, where
the screws attach same.
73
Bob, K4TAX
On 10/29/2015 4:25 PM, Jim Brown wrote:
On Thu,10/29/2015 2:13 PM, Fred Jensen wrote:
The intermittent problem turned out to be paint under a lug with a
loose screw.
That seems to be a very common problem with Astrons -- the power
system "green wire" (safety ground) is soldered to the mounting lug of
a terminal strip, which is insulated from the chassis by paint. This
is a MAJOR violation of NEC. To make matters worse, the V- terminal is
soldered to the same lug. The combination makes the unit susceptible
to RFI.
In one of my Astrons, the two sections of the chassis are insulated
from each other by paint, so the unit is essentially unshielded as well.
I do NOT recommend bonding V- to the chassis, so when you're fixing
the paint problems, cut that jumper. There's no good reason for it.
73, Jim K9YC
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