Expert: cleggsan - 11/3/2009

Question
Hitachi Big screen TV  Model# 5OUX27R  Seial# V6G003179
Date : July 1986
TV screen shrinks like the trapezoid adjustment on a computer monitor. Like this  )(  from top right and left to center and back to bottom right to left about once a month for about 2 weeks to a month and goes right back after not using it. To old for local repair people as they say they can't find parts but no one knows what it is??

Answer
Have you tried just smacking and whacking the set vigorously with your hand or fist?  This will often reactivate a bad solder joint.  Try that and see if you get any improvement or change....   sometimes it will be a random cure.

If the whacking and banging doesn't yield any result then it may be an intermittent B+ Voltage that is going up and down due to a bad or gassy electrolytic.  They age with time and are not reliable in the long run.  It is often a cause of voltage drop outs in home electronic equipment.

Electrolytics are generic parts and can be found at places like Radio Shack for a few dollars each.

If you know how to recognize them and have soldering skills - and a soldering iron - you may be able to fix it yourself. Otherwise you will need to find a brave tech who is willing to check it out.

HOWEVER: This set is getting along in years and I wouldn't recommend investing a large effort into it.