View Single Post
  #8  
Old 05-14-2007, 04:34 PM
julianburke julianburke is offline
VideoKarma Member
 
Join Date: May 2004
Location: Knoxville, Tennessee
Posts: 644
When I was doing Zenith TV's (others too) and you are not getting raster, the first thing is to pull the damper tube out slightly and if it arcs on the socket it is good and conducting. If it didn't arc you would replace the damper tube for starters to go on to the next step. (or fixed it at this point) If damper is good, next pull the cap off the the HV rectifier, stick an insulated Xcelite nutdriver or other in the cage and touch it to the cap from flyback. (don't ground it-any arc or corona is enough test) If you get arc there, you have a bad 3AT2 (or 3A3 in other sets) rectifier. Usually the HV rectifier filament opens and then will "lay" on the plate internally creating a short and keep HV from building so disconnecting the cap will prove this point. The focus 1V2 or 2AV2 rarely goes bad and if it does, will not cause loss of raster. If you still can't get it to work, measure resistance between the two caps of the HO tube and the HV rectifier (power off of course) and the resistance through the flyback should be about 75 ohms. If near zero or infinity, fly is bad. Julian
__________________
julian
Reply With Quote