[ARC5] Hallicrafters S-38 is dangerous

[Richard Knoppow]

    I don't know about the E but the ones with the half moon dials have 
a cord riveted to the back cover so when you take the cover off there is 
no power.  Of course, its easy to cheat it and one has to to align the 
IF but RF adjustments are made through holes in the bottom cover. The OP 
is right, there is an inherent danger in using an AC/DC supply, but 
considerable protection can be given by proper design. My disagreement 
was in his saying the S-38 was badly designed. IMO it was not, at least 
any more so than many consumer sets.
     BTW, one of the hints in the handbook is to insert the plug for 
minimum hum. I suspect there is increased hum when its backward, i.e. 
hot side of the line on the chassis. Of course, on DC the set just 
doesn't work at all if the plug is reversed. There was never much DC in 
the U.S., mostly in New York City in areas once set up by Thomas Edison. 
DC has some advantages for large motors of the sort used on elevators so 
the system persisted until about twenty years ago.  A google search 
would probably provide the date.  A lot of ships also had DC power.  
Some shipboard radio systems used motor-generators to provide high 
voltage from low voltage DC. National and some others, made AC/DC 
receivers specifically for use on shipboard.
     Its probably a good idea to replace the line bypass caps in these 
receivers with the modern ceramic types that fail open.
     There is an effect where you can "feel" AC on a cabinet like the 
S-38, feels like a rough surface when you run your fingers over it.  I 
don't know how much voltage it takes to produce this, maybe not much.  
The caps DO pass some AC at power frequencies, not much but maybe enough 
to give this effect.  Some AC only receivers have slightly hot chassis 
from the RF bypass caps on the power line. Again, they don't pass much 
AC at power frequencies but enough to feel.


On 11/17/2015 10:35 AM, hwhall at compuserve.com wrote:
> I have owned and worked on several S-38 receivers and am
> very familiar with the way they are constructed.
> ...
> Hallicrafters did what was typical at the time
> to protect the user.  The chassis can not be
> touched in normal use because there is a back cover
> with an interlocked power cord.  You need
> a cheater cord to work on the set.
> I assume that last half was meant to refer only to typical consumer item construction. The S-38E I have certainly had no interlocked power cord - it passed directly into the bare chassis (not to be confused with the painted cabinet). Every old TV I took apart, and some later-model plastic AM-FM sets I tinkered with, did have an interlock, tough.
>
> Wayne
> WB4OGM
>   
>
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL