Spulerious signal suppression, something was radiating off the focus or
screen lines and was being picked up possibly by the video leads running to
the crt board from the chassis. Seen lines and ramdom noise radiated into
the video in other designs, sometimes just relocating video leads from the
chassis to the crt pcb will suffice.
"Chris F." wrote in message
...
Forget the exact model number, it was a 14" set mfd around Dec. '86. This
was the first such model I've worked on, and this one had a bad flyback.
Once the replacement was installed, the set ran but had a strange bluish
haze (with retrace lines) only in the center of the screen. After ruling
out
any shorts in the CRT or supply voltage problems (cathode supply etc) I
noted that the original flyback had a strange feature - the focus and
screen
wires were integrated into one coax-like cable. The focus was in the
center,
and the screen was on the shielding. Wondering if this had something to do
with it, I took a long piece of thin wire and wrapped it around the full
length of the new focus and screen wires (together) and connected this
wire
to the CRT ground. Success!
Anyone care to explain what was going on here? I've never seen anything
like it before......