[ARC Tech-109]

I could and have given thought to that but honestly I'm quite pleased with the performance using the RF input, I did leave a provision to add a composite input by soldering a two post tag strip to the top of the IF section cover shield and ran a wire to this for testing right off of TP2 and this goes directly to the grid of the 1st video amp.

The video amp is responding well and I get roughly 300 or so lines of horizontal resolution that's actually limited by the dot trio & aperture of the CRT itself, chroma response is good without the shading or fading that I was getting earlier. Convergence is what it used to be "back in the day" which is to say acceptable. It always had a slight bit of blue error on the right side that dipped down slightly and the only time it was annoying was when I was doing the ATARI 800 BASIC thing back in the early 80's.

The one annoyance is with the slight horizontal sync bending and the dark shading following the highlights and sometimes the vertical wants to follow the black bar used to adapt the 16:9 aspect ratio to the 4:3 frame in the modern DTV receiver boxes, wondering if video is sneaking into the sync somewhere but the scope didn't show anything during the last probe. I've gone thru the AGC section several times and everything is as it should be in terms of values, the 6GH8 is new from the carton and my signal strength is a measures -86db/m at the 75/300 ohm matching transformer coming from the test port of a Blonder-Tongue CAMS-60 MTS modulator with the RF drive all the way down. Thought it was an overload so I tried a different consumer grade modulator and got the same results so I'm out of ideas as I'm totally missing something here.

Vertical is still a little challenged and if I pull the height any further it loses lock and goes into this cycle of collapse then startup again only to collapse a second or so later never locking onto the sync. Supply line shows a constant +394V after the 1K/3W resistor (R112) and C5 is known good. Boost B+ is running 1196V give or take a few and I'm not seeing any horiz ripple on the supply side so my conclusion is one of the "new" parts isn't doing so well here. Plenty to keep me busy for a while.


I do have to give a big thanks to all the members who have put up with my long-o tell-o posts and given me the pointers and directions, also want to thank damen and Danny S. for their help with the replacement pieces. Without their help I'd still be at square one.

Danny if you're reading this I have not forgotten about you, just a little short on the spare change at the moment. Thanks again for all you have done.

Going to watch the set for a few more days while taking notes before I pull the back off once again, I'd leave it open but I do have three curious kitties in the house and they don't take no for an answer.

I will post a short video of the set warm-up and picture itself showing the bending and shading, this will be done in HDCAM so everything can be genlock'd together to eliminate the flicker effects.