THE VIC20 RF CONVERTER: A COMMON PROBLEM AND ITS SOLUTION
             Latest updates and/or corrections 1-14-2014

I own several of those little boxes but never actually used one until 
recently when I discovered most of them didn't work. The TV screen 
showed only a white screen with some diagonal lines running through it. 
I have seen only two versions of that metal box, one made in Japan and 
the other made in China. Strangely enough, the ones made in China both 
work fine. They are of a different design. The Mitsumi modules inside 
the ones made in Japan were now somehow defective after all these years 
of just sitting unused. They all suffered this same problem. 
     Inside the metal box, there is another tin can which contains the 
converter module, and a small switch. The outer cover is held with one 
small screw. Remove that cover by sliding it sideways and off. The 
module inside must be removed from the box (two small screws) and the 
wires to the switch disconnected to gain access to the module. It can 
be opened by prying off the covers on both sides. Note that one of them 
may have some solder holding it down. After removing the covers, I 
found that two small electrolytic capacitors (10uF @ 16V) inside the 
module were starting to leak electrolyte onto the reverse (solder) side 
of the board. That corrosion must be cleaned off and the two capacitors 
replaced. Those bad caps are the cause of the converter failure. See 
the photos. 
     Because of the corrosion, if the solder will not stick to the 
copper pads where the old caps were removed, follow the copper traces 
to the next solder points and attach the wires there. Once that's 
done, the module covers can be put back, the module reinstalled and the 
wires to the switch reconnected. Put the outer cover back on and you're 
done. 
     Note: the video level adjustment in the computer can be advanced 
to give you a better picture if you're using a direct A/V connection 
via the DIN connector on the rear of the computer. However, if you're 
using the RF converter and a TV set to view the computer, turning the 
video level control higher than normal will overload the converter and 
corrupt the image. It will appear as a negative image with a bar 
running through it. If that's the case, turn up the control enough to 
get a bright picture but not so high that it distorts. 

Ray Carlsen
CARLSEN ELECTRONICS