Just put an LCD monitor on an A4000 for the first time and I have a question..

[A4000_Mad]

Hi Guys,

After using the CRT monitor in my profile pic on my A4000 for years I bought my first LCD one for the Amiga yesterday. I'ts a 15" Philips 150S1C/00Z.




The CRT monitor has a nice, clear display and even old games scan double onto it nicely. However, the picture on the LCD monitor is very grainy and when old games are scandoubled there are very noticeable vertical lines on the screen.

I'm no expert on frequenceis etc, but from reading an online manual it is clear that this monitor likes 60 Hz. Could the problem be that the Picasso II being used and the motherboard mounted scan doubler are producing only about 50 Hz? I guess the scan doubler cannot be adjusted, but could the Picasso II driver be altered to make it deliver 60 Hz?

Thanks,

:drink:

[Matt_H]

According to the spec sheet, it looks like the minimum vertical refresh is 56Hz - just slightly out of range. I have a Samsung monitor here that behaves similarly badly - scandoubled PAL screens show up, but the bottom is cut off with no way to properly center the image.

It should be easy to put the Picasso to >60Hz, though. Just use CGXMode or P96Mode to make sure its screenmodes are set correctly.

[Ral-Clan]

Also remember that most LCD monitors have an ideal native resolution.  Any other resolution used on them will look less than ideal.  Looks like this monitor might use 1024 x 720 or something.  Any other resolution shown on such a monitor needs to be re-scaled on the fly to the monitor's native resolution and it usually doesn't look great.

That is the big advantage of CRT monitors.  They can re-adjust their scan-rate and vertical/horizontal resolutions to (almost) any spec and it will look great.

I just bought a newer widescreen LCD and although it is stunning in its native resolution, I do miss the old CRT's ability to do crisp 640x400 and 800x600.

[Zac67]

You might want to raise he vertical scan rate to 75 Hz to reduce screen tearing. 100 Hz would eliminate it completely.

@ral-clan

All LCDs only produce crip output at their native resolution. It's rather obvious that the required rescaling reduces sharpness. (Unless you hit a multiple of the original resolution, e.g. 640x512 => 1280x1024 or disable scaling and live with a black frame around the picture.)

[tone007]

The vertical lines can sometimes be lessened/removed by adjusting the monitor's clock setting, if it lets you.  Those come up all the time with the old scandoublers and LCDs.

[Selles]

Just use a 17 inch, flat-picture tube CRT ViewSonic monitor.  Then you will have a nice clear display.  The ideal resolution for most flat panel monitors is 1280 X 1024.  So, unless you are using a Picasso IV or a Cybervision 64/3D graphics board, do not use a flat panel monitor, use a good quality crt monitor ( like ViewSonic ).

[A4000_Mad]

Thanks very much for your help guys

A very detailed manual was here:-

http://www.p4c.philips.com/files/1/150s1c_00z/150s1c_00z_dfu_eng.pdf

I used  its OSD 'auto adjust' and 'video noise' functions and got some improvement and also had a nervous tinker with P96Mode. But in the end I used my brain cell and realised it made more sense to just put in on the A4000 with PPC and Cybervision64/3D which I mainly use for emulating arcade games with MAME and Sega Games with AmiGenerator, and also for watching videos with Amp and FroggerNG. Although capable of scan doubling, I never need to do it with this particular machine as I don't run old games on it. The Cybervision64/3D must be set up better or just a better card as I'm getting better screenmodes and a perfecly still picture


EDIT

@ Selles .. You were spot on with that thanks

:drink: