I don't have the circuit diagram in front of me, but I would suspect a shorted or leaky capacitor in the output circuit. Another possibility is that the heat sink is inadequate or something is amiss with the thermal interface between the IC and heat sink.
Is the vertical waveform normal? Put a convergence pattern up and see if the grid is linear from top to bottom. This could give you a clue.
Two more possibilities: there may be a conductive burn track in the circuit board in the vertical deflection circuit area. This could be putting an additional load on the IC. If you find this, you get to play dentist - mill out the burn track, (it will be softer than the good material), clean off any carbon residue and fill it with epoxy.
Another possibility is that the vertical IC comes in multiple versions with different voltage and current ratings - the only difference in part number may be a letter or number in the suffix. If this is the case, you may have installed one with too low a current rating. To check for this, download the datasheet for the IC (search for the part number AND "datasheet").
×
170 views
Usually answered in minutes!
×