An amplitude modulation receiver that's in Air-cooled VW Super Beetle has some inconvenience, scratching noise in the potentiometer and channel selection knob does not work, preset piano keys move with heavy action. In addition, sensitivity is dull. So, I determined to replace it into more uptodate one, preparing two pieces with Frequency modulation waves. Before proceeding to the procedure, I disassembled and opened it finding out so lovely pure mechanical movement of pre-set station selector. This beautiful construction produced half a century ago obliged me to change my initial mind.
Consequently, I made up my mind to reconstruct it as it had been 50 years ago, oiling and greasing on the all of the slipping and penduram movements, and indispensable replacement of electrolyte capacitors, the were all different capacitances with 9 pieces costing 485 yen in total.
Crogging and Inhibiting wall to be ridden over for me in order to repair as it had bee is tandem connected potentiometers for sound control and loudness also a main switch is connected together, it's almost impossible to find out the same kind of mechanical electric part however hard I might seek in the Websites. Very high and difficult wall shutting out my intention! How come?
It took me a minute to find out the way to solve the problem, I applied special magic technique to survive the worn out volume resistor unit. As we know, the resiter material, often carbon layer is scratched only on a line along with mediorinal figure, so carbone surface would be revived like new if the lines were moved--- out or inside. The metallic case of the round rotating potentiometer has often small windows for heat measures, you can recognize a moving terminal with spring action. Push or pull it without hesitation with adequate pushing power to change the tracing arc radius---resulting like new part.
For example, an old servo motor in my Radio control model airplane produced 50 years ago is still in the air even now, of course exactly the same mending method in the potentiometer had been invited on the potentiometer inside.
Though a bit an antenna impedance adjustment and Intermediate Frequency Trans(IFT) was required, S/N separation and sensitivity were obtained after all in spite of it's half a century circuitry ancient design.
Another critical problem was uneven stylus movement in the fuel gauge, the angle of stylus does not show full tank position in spite of actual condition. As we know, '71 Super Beetle has the meter coil and fuel tank sender resistor comparison thought design applying some standard voltage supplied by bibelator. The voltage stabilizer is constructed with pure mechanical design, bi-metal and pulse production. At the beginning, I planned to replace this primitive voltage stabilizer into a Semiconductor #7805 at 5.0V. Later consideration led me to change my idea---keeping the original construction as much as possible to restore VW Super Beetle.
The way to change the output voltage of the stabilizer is reducing the pulse width---this is done by the terminal distance adjustment---10 to 15 degree turning in. As the stylus moves fair after adjusting after all, the concept "Restore the original condition" was followed excluding recent electric part invasion.
As for speed meter wire cable, periodical maintenance is required, otherwise lack of lubrication will damage the connection connection between the meeter and left front wheel. Some tear drops of machine oil at the hub center solbs the threatening problem. Counter clockwise coiled wire will transmit the lubricant upward to the meter craster. Consequently, too much application or a stupid attitude from the meter side will damage the claster.(It's often the case, oil soaking.)
Illumination balbe at 10 o'clock position was out order, filament was alive but vacuum condition was lost. Utilizing the original socket, balb was replaced and the performance of the meter craster was survived safe.
