There's an idiot in the next county who quickly solves convergence problems on RPTVs by misadjusting the optical focus of the offending color. I have run into this before, but this one was different.
RCA PTK195 based unit, one of the ones with the anti glare screen (we have been paid at times to remove them). Red and green focus out, just a little, in the same amount and direction.
This unit may have not been serviced before, no missing screws, holes are tight and the little clips are still in the chassis pan.
At first I thought maybe the plastic lens body shrunk, but no because I adjusted them down for good focus. Did RCA simply use a calculated setting and just assemble the set and let the computer align it without ever looking at the picture ? I don't know about you, but when the optical focus is off it seems to give me a sort of eyestrain, and the closer I get the worse the eyestrain. I can almost tell just by that whether the optical or electrical focus is off.
In this case of course the back is not plastic, on a plastic cabinet you get that tick sound when you are the first one to take it apart, can't say for sure on these, but I got a tick out of the lenses and they were quite tight. I have seen a few cases of tampering with optical focus, but usually it is just one color. This was two, in the same amount in the same direction. Can't say about the blue, didn't need to bother with it.
I can't think of any reason for this. I also do not understand why the optical defocusing causes eyestrain whereas the electrical does not. Bad optical focus literally makes my eyes water, and I am not alone. I had to go on a service (eeeek) call about 4 months ago to do an inhome alignment (what fun). It was a 169 based RCA and it was too hard to get the cabinet out of the home. As usual in such a case I set it up to project on a wall or something to get an idea of the geometry and convergence.
In this case the alignment of the R & B to G did not match the optical focus. The customer was not all that happy with the picture. He had bought the set used and I figure it was a transplanted box, done by someone who knew something but not enough. As soon as I walked in the door I knew, I said "You are gonna love this", told him to stick this DVD in and hit track 5. (I will not touch any other of the customer's equipment in a case like this, unless it eats my $60 test DVD). When the guy saw what I did he brought out a beer and a joint. Somebody had simply adjusted the center convergence, after the focus and dynamic convergence was set he was ecstatic. "It never looked that good".
I told him that probably one guy had one that didn't work and another guy had one with bullet holes or something so they built him a TV like the Frankenstein monster. Thing is, this is all explainable, the latest case is not.
JURB