[SEDXC] Looking for help on older TV

[Jeff Carter]

It's been some time since I was repairing televisions for a living,
but based solely on
what you've said and not seeing the unit, it sounds like you're losing
vertical deflection.

This usually happens when the circuits that drive the vertical
deflection coils on the neck of the CRT (the "yoke")
begin to lose either drive or Vcc.

In a set of that age, the vertical deflection circuit could be
discrete transistors in push-pull but is more
likely an integrated circuit mounted to a heat sink pretty close to
where the yoke plugs into the main board.  Check
the IC for bad solder joints (these happen from heat over time).  If
that is not it, check the capacitors in the circuit.
Electrolytics dry out over time and cause this symptom due to high ESR.

If it isn't that, you're looking at breaking out the 'scope and DMM
and running down where you're losing either
the drive or the input voltage, which is usually derived from the
secondary of the IHVT (flyback transformer).

Good luck!

Jeff/KD4RBG


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I have a 8 or 9 year old Panasonic 32 inch TV that is losing vertical.  Of
course no xxhematic came with the TV and the on screen controls are only for
color, brifgtness etc.  My 17" monitors for the PC
do have a control for horizontal and vertical (of the picture).

Is there such a control inside the TV (none outside (front or back)?