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Korting 1047  Export to USA for Delmonico model Novum

This radio's name is Delmonico model Novum.  It was made by Korting in Germany.  Chassis number 24433 model 1047.  Six tubes single ended output and an EM84 tuning indicator. This chassis incorporates single sided Printed Circuit (PC) boards.  In my 44 years of repair experience I have found these PC boards are prone to cold solder joints where the tube sockets are soldered to the copper traces.  I believe this is due to the thermal cycling of the solder joint and not a factory failing.  This same problem can also be seen in modern electronic equipment (computer monitors, printer power supplies, etc) where a component heats up with normal use.  Another noted problem of PC boards of this vintage unit (not this particular chassis) can be carbon trails from cathode to anode across the grid in the audio output tube.  This causes the grid to go positive and make the output distorted.  More can be read about this carbon trail at:  http://people.cs.uu.nl/gerard/RadioCorner/Sets/Ko23621.htm

My biggest challenge with this chassis was finding an alignment procedure that I could read.  Most of the procedures for this radio are printed in German.  I compared a few similar chassis against the circuitry of this chassis, identified similarities and used an English procedure to properly align the chassis.  www.Radiomuseum.org is a great resource for such information. 

The restoration is quite straight forward.  One note is this manufacturer used uncoated carbon composition resistor unlike other manufacturer use a resistor that has a plastic coating keeping the moisture away from the core.  I found two or three out of tolerance resistor so I "Shot-Gunned" replaced all of them as in an American made chassis.  The electrolytic and paper capacitors were also replaced.  The original ceramic and polystyrene capacitors were left in.  I have found Polystyrene caps to be stable and good as is the same for Mica and ceramic capacitors.

Three Electrostatic tweeters are in this chassis.  The suffer from deteriorated foam rubber pressure pads and corrosion.  See also the "Electrostatic" page for additional How To restoration tips.

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