[VAC] Univolt converter

[Thomas Griffith <tgriff90@xxxxxxxxx>]

Hi everyone:

Another question.  While installing a new sound system in our 1970
Overlander this weekend I discovered that when hooked to shore power I
have a very bad AC hum in the speakers.  

I haven't hung a 'scope on it yet but it appears that there is about
800mv of ripple on the output of the converter. 

From what I can glean from the internet, these older converters were
famous for a trashy output.  This one is so bad that I feel it must have
a bad output filter.

Does anyone have a schematic for this unit?  If so, I'll gladly pay for
copying and mailing.  

If this thing is really this bad, what are some of the other fixes
people have come up with?  Just don't attempt to listen to music while
on shore power?  Build a special power supply for the sound system and
switch it from AC to battery when boondocking?  Tear out the entire
converter system and use a battery charger instead and run everything
off the battery while plugged into shore power?  (not an attractive
option) 

Thomas E. Griffith  N5GF
1970 Overlander  WBCCI #25776 at large
West Monroe, LoUiSiAna