serial Nr.V837440
Table top valve radio Made by Blaupunkt in Germany. This
radio which belonged to her late uncle was kindly given to me by Imogen
Radford.
I understand that this model was first produced in 1965 though
Blaupunkt used the name "Sultan" on several models with a similar valve
line up. The "Stockholm" is the same though housed in a longer lower
casing. Have a look at the "Nizza" model which I also have in my collection.
This is a well made AM/FM radio with VHF, Long, Medium and Short
wave bands housed in highly polished wooden
cabinet (504x310x215 mm). It has one main elliptical loudspeaker and
two smaller
high frequency ones mounted on the sides. The valve lineup is as
follows:
ECC85, ECH81, EAF801, ECL86, EM87 and solid state rectifier
B250C75; the dial lamps are 7Volt 0.3Amp and there are two fuses: a
300mA slow blow and a 4A quick acting one for the heater circuits.
View of interior Note the three loudspeakers and separate
power supply
View of underside of the printed circuit board (the on/off switch
is on the left)
There are no screws to get lost,
the back is held in place with clips
Surprisingly it came in the
original packing box
This model has a single triode pentode
output stage rated at 4 Watts. The printed circuit board has been
designed to accommodate a valve holder for an additional ECL86 for
other models used in radiograms with stereo outputs.
When I first switched on the radio the dial lights lit up and almost immediately the set went dead. No bang, no smoke, no smell. I discovered that the 300mA fuse had blown and that the contacts on the on/off switch then failed to make contact. After dismantling the switch I found that the contacts were completely black and after cleaning and putting it all back together the radio came to life with a new fuse. I can only assume that the initial poor contact had caused arcing and the resultant inrush current to the transformer caused the fuse to blow.
The set then worked well on the FM wave band and the magic eye indicator opened and closed as stations were tuned in but on the other wavebands there was plenty of noise but I was unable to tune to any stations as the mechanism was completely solid. After unplugging and removing the power supply I was able to remove the main chassis from the case and soon found that the problem lay in the seizure of the geared drive on the variable capacitor. In the end I removed the hub on which the drive cord is wound and the three screws (one is longer than the other two) which hold the spindle and gear wheel in place to find that the grease inside had solidified. When the circlip was removed a knock with a hammer released the two parts so that they could be cleaned and lubricated.
The offending part and stringing diagram
After washing the knobs and glass scale
plate, blowing out the dust, cleaning the valve pins and putting it all
back together the radio works very well indeed .
