|
What is likely happening is the IF amps momentarily going into cutoff or saturation, usually happening when there is white lettering in the video. If the video IF goes into cutoff or saturation, the sound subcarrier and or the video carrier gets obliterated for a short while, pattern repeating at the vertical rate. In the intercarrier system, the video detector sees the sound carrier as being 4.5MHz away from the video carrier, and converts it down to 4.5MHz. If the video carrier goes away, there's then no converted sound carrier, and the picture looks peak white. Thus the sound detector ends up with interrupted sound at a 60Hz (vertical) rate, which sounds like buzz. If the picture looks to be blooming white (like an overexposed photograph) you're losing the carrier (peak white on video happens at minimum amplitude modulation of the picture carrier). You may want to check that the voltages on the IF tubes are correct, or maybe too low.
__________________
|