Focus

Some of you may laugh – but in investigating doing the astig on my Ampro I discovered that I had never understood the best way to optimize the electronic focus control.

Accessing the internally generated patterns:

  • Press 1, [test] and use [step] to select the dot pattern
  • Cut off all but one tube. (repeat for each colour)

Now by looking at the dots – you will see a huge difference when playing with the electronic focus. In the past I had used a crosshatch pattern to see the effect of focus – but this really hides the differences. Maybe I simply had not looked closely enough, but using the dot pattern makes it really obvious. I honestly in the past had thought that the electronic focus control on my Ampro had limited value – I was wrong. This also helped me dial in the mechanical focus a bit tighter too.

Now in terms of astig. I clearly have both beam centering and astig issues – not really bad, but enough that working on it is going to should have a noticible effect. I, like many, run my CRT with a 16:9 screen – this means that I need to vertically squeeze the image. This vertical squeeze has caused the default 4:3 setup of the CRT with round dots, to have squashed oval dots. Additionally it is clear that the beam centering is not perfect. More on this when I get to tweaking it.

In regards to the DVD player switch and moving from component to SVideo on the quadscan – it was a good change. I haven’t tried alternate component cables yet, but having done some searching around on the net it appears that at least some folks in the past had had issues with the quality of the component inputs.

Lines..

Well, for quite some time I’ve been having some noise lines appear on the screen – primarily with red, but it appeared that all 3 tubes were affected. I wondered if this was the projector or the signal. Having recently played around with checking the grayscale – it was pretty obvious my line problem was getting more serious – the lines were pretty obvious during the test patterns. Normal video material was mostly ok, but some movies such as The Incredibles really showed the problem in some scenes.

My HDTV source is a satellite box (starchoice) and it didn’t appear to have the same problem, but with the amount of MPEG2 compression artifacts it is hard to be certain that there isn’t a problem. Of course if it was my source – then it might be my DVD player, or my quadscan, or the cables.. so many items in the signal path that I couldn’t easily isolate.

I had figured that using the transcoder I have plus my ‘extra’ Sony DVD player [DVP-NS50P] running in progressive mode I could bypass the quadscan. This was relatively easy to try out, and it seemed not to have any problems – other than the somewhat questionable transcoding. No lines.

I then tried the Sony DVD player via SVideo to the quadscan, and again – no issue. Hooking up the Toshiba DVD player [SD-2109] via SVideo instead of my usual component connection the lines also seem to go away. This is an interesting A/B comparison since the Toshiba has both outputs active in parallel, so I can switch between the two outputs and verify that the signal is cleaner on one than the other.

The Toshiba seems to have a very subtle noise in the signal (almost like a ground loop hum) that I don’t see with the Sony. While the trusty 2109 has served me very well for many years, maybe its time to retire it. The 2109 was a great (quality) player, but at this point in time it seems like the (cheap) Sony has an edge on image quality.

After digging around to remove the 2109 from the rack (what a mess back there) – and getting the Sony in place – it appears that with component input I still have the same noise problem. The Sony SVideo is still cleaner than the Toshiba – so I’ll stick with it for a while. The component cables may be the problem, but it may also be the quadscan’s ability to process component input.

CRT Forum

I finally decided to sign up to the CRT Forum hosted by Curt Palme it seems to have a pretty active CRT projector section and not all of the discussions end up being mirrored on AVS in some way. I’ll likely just lurk, but I intend to at least visit regularly.

There was a post by Scott (tse) who knows a lot about Ampro systems. In one posting he comments:

The six devices attached to the registration amp heatsink have thermal shutdown circuits built in. They will turn off if they overheat. Once cool they will turn back on. So if the green vertical amp overheats the green will jump to the position it is in when registration is turned off. Same for blue horizontal, red vertical…..

Check that the screws are snug, they can loosen over time.

Now in this context he was talking about an Ampro 4200, but I’ve seen this same thing happen with my 4000 and hadn’t put 2 and 2 together. I’ve seen the convergence suddenly ‘jump’ to have a huge drift. Entering the help/setup menu would show that things were not really that bad – I suspect that the setup menus reduced image levels result in the system cooling off somewhat. In these cases – the room temperature had risen quite high – probably a bit more than 30C up at the ceiling.

Calibration: initial measurements of the Ampro

So the fancy mounting of the sensor to my tripod ended up being some painters green tape.. I set the spyder sensor without the LCD filter attached facing the screen (to capture reflected light from the screen) a few inches away from the center – and at a slight angle to avoid the shadow of the sensor itself. A quick run with AVIA to get IRE10 – IRE100 and I was able to capture some interesting data.

Gray Scale 1

While I didn’t let the CRT run for more than about 10 minutes, things clearly need improving. I tested the uncalibrated screen of my laptop with the sypder sensor and it read fairly flat (if you ignored the low IRE numbers) – as I would have expected – so I have some level of confidence in the software actually trying to do something sensible.

Of course – now I need to learn how to properly interpret the data, and what steps to take in order to make sensible improvements. The absolute first thing I should do is a full setup (mechanical, etc) of the basics. Its been a long time since I’ve taken the time to properly calibrate the system doing the things that I know how to do.

I did come across a useful article on Curt Palme’s site. How to set G2 on ES focus sets. This isn’t how I’ve done it in the past – having simply blanked the tube (to give a completely black image) and then set the G2 such that the raster just disappeared. Having just searched this blog for g2, it seems I haven’t taken the time to really sit down and document a full setup procedure – and I should as it would serve as a good reference for myself later on.