View Full Version : Andrea T-VK12 -- Lightning Strike to Antenna?


Polaraligned
11-20-2016, 08:37 AM
I cleaned up this chassis real nice, and the cabinet is in super nice condition. Taking a close look underneath, I noticed what look like the signs of a lightning strike to the antenna input.
You see here what is left of the mica capacitor going from one antenna terminal to ground:
http://img.photobucket.com/albums/v223/polaraligned/Andrea%20T-VK12/IMG_4374.jpg (http://smg.photobucket.com/user/polaraligned/media/Andrea%20T-VK12/IMG_4374.jpg.html)

Then there is another blown up capacitor from the antenna input going to the AM converter. It is not shown on the schematic, but this looks like a factory revision. It is between the antenna terminal and L15.

Then there is L30, to the right of the capacitor in pic, is tests open.
http://img.photobucket.com/albums/v223/polaraligned/Andrea%20T-VK12/IMG_4376.jpg (http://smg.photobucket.com/user/polaraligned/media/Andrea%20T-VK12/IMG_4376.jpg.html)

Here is the schematic.

http://img.photobucket.com/albums/v223/polaraligned/Andrea%20T-VK12/IMG_4378.jpg (http://smg.photobucket.com/user/polaraligned/media/Andrea%20T-VK12/IMG_4378.jpg.html)

This set has me concerned because somebody took the safety interlock switch out, and installed a fuse in the line. The set is totally unrestored and sports all of it's original paper caps.
The HV cage cover and the HO tube were missing when I got this set. Of course, that has my concern up that there is a potential flyback problem.
http://img.photobucket.com/albums/v223/polaraligned/Andrea%20T-VK12/IMG_4377.jpg (http://smg.photobucket.com/user/polaraligned/media/Andrea%20T-VK12/IMG_4377.jpg.html)

Luckily, I have obtained another T-VK12 that had a basket case cabinet. The chassis in this parts set looks unmolested. It is an earlier serial number and does not have a few of the updates that the set in question has. I spent a lot of time cleaning the "lightning strike" chassis, so now I ponder whether to clean the parts chassis and restore that, or precede with this one that is clean and on the bench. Of course, I can swap parts as needed, but it is always better to start with the best set possible.

The set is loaded with those HI-Q ceramic tubular capacitors. I assume they are fairly reliable, as are most ceramics. What would be a good replacement for these? I know the temperature coefficient is very important with ceramics. Of course, I will only replace as needed. I have no plan on shotgunning those ceramics.