The set is a 29"CRT TV, model 29PT5683/69 its about 7 years old. The problem is the set produces only blue retrace lines.

However the sound is fine. Mute, increase, decrease volume all works fine. Monitor out into another TV produces picture.

I've checked most components on the CRT neck board. 200V is preset at this board. The RGB amplifier chip TDA6107 has been replaced.
RGB signals to TDA8844 has been bypassed with capasitors and picture was available, but upon removal of the caps. only retrace line like the picture is available. Reinstalling the capasitors again produces only the retrace lines. TDA8844 has been replaced with no improvement. High voltage from the flyback is about 30.57KV.

Any idea what else could be the problem based in the pictures posted? Thanks.

it looks like the horizontal frequency is way off. it doesn't quite look like retrace lines to me, because they are too clear. but i could be wrong

is supply for the TDA6107 ok? it comes from the 200v
but a resistor could be bad.Try to reduce the UG2 also and
you could disconnect the blue gun to see what happens.

If I reduce the G2 the second picture is what I get. I've checked the 200V at the crt neck board and it is available. I will try and disconnect the blue gun and see what happens but I think it is due to blue screen that is preset when no signal is available.

I don't think its a tube problem, since I've bypassed the RGB inputs to the TDA8844 chip with capasitors and managed to get some distorted picture. Upon removal of the capasitors the lines are all that I get. Replacement of the TDA8844 also does not improve things. I somehow feel its something to do with this chip.

Looks bad sorry, I suspect its the tube as you seem to have purity issues as well. I agree take blue out by dry jointing the cathode and check the results, I suspect it will still be bad.

Whats the voltages measure on the catrodes?
you have a lot of vertical retrace there if the set has a vertical ,,pincushion, problem will see this.
i had a bad fly back do this too,measure those cathodes on the crt socket should be 135 to 170volts you cant unplug the crt when you run set it will blow the tda6107
ic also there is a 10 ohm resistor and one outher resistor that goes bad,scope those cathodes see if you have 180 vpp video there if you have a tube problem it wont be there.

Did you ever get to the bottom of this problem?