Restoration report Telefunken 686 WK -1936 (Techniek Radio/TV)

door edison , Aveiro - PORTUGAL, 10.11.2024, 18:36 (11 dagen geleden)

Hello everybody.
I present to you my latest restoration, which is a Telefunken 686 WK, year 1936.
It was completely undone, with a lot of corrosion, but it was complete with all the valves (except the rectifier) and buttons.
After checking that the power transformer was good and the output triodes still had some power, I decided to restore it.
The biggest problem was the box, which was very damaged by humidity.

The electronic work carried out was:
- Replacement of all electrolytic and paper capacitors.
The paper capacitors are, almost all, inside metal boxes, and it was necessary to rebuild a
- Checking all resistances and replacing those that were open and out of tolerance.
- Checking all coils.
- Changing the volume and tone potentiometer.
- The interstage transformer was ordered to be rewinded, as the output is PP.
- It was necessary to rewind the tuning indicator, which was open. The tuning indicator is a mechanical "window", with a lamp behind, and the larger the signal, the stronger the magnetism, created by the coil, opening the "window" wider and thus projecting more light onto a bar on the dial.
At a mechanical level, the following was done:

- The chassis was cleaned of rust and painted, as were some parts.
- The switches were repaired, as the plastic parts had many cracks, and all contacts were improved.
- The steel pointer control cable was replaced and the fine tuning mechanism was repaired, as it did not work.
- The speaker has been cleaned and painted.
At the box level, the following was carried out:
- The box was completely rebuilt, with everything that wasn't damaged being used, with the side part, the upper top and the inner part that carries the cloth being made.
- Then it was completely veneered with Rosewood wood, which was the original.
- Dark coloring was given to match the original.
- Then it was varnished with Shellac.
After these explanations, I leave them with some before and after photos.
I hope you like it.

--
From PORTUGAL, with regards
Carlos