HDTV Convergence on Toshiba TW56X81 (1 Viewer)

[DwainW]

Believe it or not, I've had HD on my Toshiba for over a year and I still have not been satisfied with my convergence/geometry yet. It always seems like a compromise of some sort every time I tweak my set. For the longest time there was the problem with broadcasters running slightly different picture sizes and alignments, but now that most of them seem to be using more standardized safe areas, I have a new problem.

After numerous adjustment sessions spread out over a long period here is what I'm having difficulty with:

The HIT and WID adjustments seem to do no good if you plan on using convergence grids as specified in the TW56 service manual. I feel like I must be missing something, but shouldn't picture size be adjustable beyond the templated convergence. Instead, what I think I'm seeing is that the templates determine your picture size and HIT and WID actually end up just giving me strange distortions if I reconverge with the templates. Now on bright uniform screens (skyshots and such) I can see a gradient between light and dark bands on my screen that seem to be bright across areas that correspond to adjustable lines on the convergence grid and darker bands in between. There are five distinct bright areas horizontally across the screen. It is like the scan lines are actually stretched apart (relatively speaking) in those areas of the screen between adjustable convergence grid lines and bunched up around the adjustable lines. Now I am not 100% sure that this is the result of fiddling with HIT and WID, but I only have noticed it after the last session of trying to set my HD picture size and then converging to the service template.

Is this something anyone else has observed? If what I think is going on IS going on, how can I reset HIT and WID to the proper (not necessarily factory) settings without an enormous amount of trial and error? Should I make new templates based on a new calculated smaller picture size? Am I just totally not thinking straight? I've been able to get much pleasure out of my Toshiba in almost every respect, thanks to the wonderful Keohi site, but this HD geometry just seems to be eluding me. Any insight that someone could share would be very helpful.

For the record I'm using an RCA DTC-100 with the RCA transcoder. All other inputs (S-Video and 480p) have been sorted out satisfactorily. This phenomenon only affects the HD input.

 

[TonyD]

dwainw i just stumbled on this old thread. hope your still monitering this.

have you ever come up with a solution for this?

i have the same observation on my tosh.i get spped bump like bends when the picture scrolls and it is very annoying.

i also notice that near the middle just below the horizontal middle of the screen during bright scenes that it is brightwer slightly in this area. likely due to the grid not being adjusted properly.

and have been trying to find a place in my area that i could get a grid made up so i can fix it.

i have the grids on a floppy using an adobe program but one of the places i found wanted almost $300 to print up the 3 grids on paper.

so i knew that couldnt be right and am looking for another place.

delaware county pa if anyone out there in this area ever had grids made up or knows were i could go.

i have the acetate. the only thing i need is the grid on paper so i can copy it to the acetate.

 

[DwainW]

Sorry to take so long getting back to you, Tony. I have not been able to solve my convergence problems. I have been trying several things to locate the actual source of my problems (or rather, why I thought I needed to do what I did to cause the problems).

It seems logical that if I were to backtrack my convergence/height adjustments, I could eliminate the 'speedbump' problem (I like that analogy) and attack the geometry problem from a different angle. I decided to draw up grids to my own proportions using measurements that I would calculate from actual measurements of known objects on my screen. So I ran my Avia Test DVD through my VCR so that I could then run the RF out into the RCA and view the scaled output in 1080i. To my surprise, circles were within a very small amount of being round! So if this scaled output was geometrically acceptable, I realized that the original vertical stretching that I was trying to eliminate was not a universal characteristic of the DTC-100 nor my Toshiba. After careful examination, it appears that the stretching that I have been seeing is only from Directv. So if I can solve this new issue, I would feel more certain of my calculations for new grids.

So now I have new questions:

Does anyone know if the DTC-100 handles Directv output differently than OTA output? Can these be adjusted separately in the RCA's service menu?

 

[TonyD]

well dwain i still have the problem

and the frustrating part is that i havegrids now and after i try to set hit and wid to lessen overscan, it goes right back to were it was after i use the grid to straighten the lines.

now i even have a new problem and that is i am getting horizontal thin, flickering black lines across the top 6 or 7 inches of the veiwing area of the screen.

i am about to start a thread on that to see if i get anything from anyone on it.