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RANK A774 CHASSIS
The line and field sync are very weak, the picture pulling
over to the left and rolling every minute or so. The fault
disappears when the printed board is flexed, but no breaks
can be found in the tracks. The symptoms also disappear
after the set has been on for about an hour.
The trouble is due to poor contact between the tags of the
vertical struts on the main frame, at either side of the tube
neck. These tags protrude through the panel in about four
places, from top to bottom. First remove the solder from
those earthing points to expose the tags. Clean the tags
thoroughly (you’ll probably notice that the solder never
“bit” into them all in the first place) and tin them. Then
resolder, and run a lead from the top to the bottom to
ensure that the earthing is good even without the efficient
contact of one or more of the tags. Solder each lead in four
places in order to back up the vertical metal strips.