Falcon display issues - update

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smoore100
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Joined: Wed Apr 03, 2024 5:45 pm

Falcon display issues - update

Post by smoore100 »

Hi All

So after a couple of weeks of playing around with the Falcon definitely seeing some progress.

Recapped the PSU, then the transformer on the original PSU got very hot after running for an hour or so, and seemed like it was leaking blood from the top - probably some kind of resin and not actually blood - unless the Falcon is possessed.

Bought a new PSU from Exxos and installed very neatly - not by me but by somebody who knows what they are doing.

The 14MB upgrade that came with the machine was a poor fit, very wobbly as the RAM was basically sitting on top of the ROM chip and not reliably working - bombing out frequently. So put the old 4MB card back in and have another expansion on the way.

So after the above, setting the resolution at 640*480*16 gives me the most stable desktop on the Dell monitor - using the 3 in 1 adapter in VGA mode.

BUT, I still get weird jittery behavior from time to time, and this gets worse the longer the machine has been used for.

Running Gembench shows that ROM and RAM access are lower than I'd expect, I'll rerun later to confirm but RAM access was around 80% and ROM was even lower on a coupe of occasions. Bliiter was low as well but I'm putting this down to the increased colour depth on my display compared to the baseline, and trying to set it to 2 colour makes the display to unstable to use it!

I tried the diagnostic card, which actually worked now the PSU had been upgraded - last time I tried I struggled to a get a display.

Running the VGA video test seems ok for the first couple of tests but then I get a screen of garbage on test 3 - I am working now but will take pictures later.

The strangest thing is when running the keyboard test from the cartridge, I can make the display 'wobble' by moving the mouse, and this is 100% replicable.

Until I had spotted this I was definitely thinking the monitor is my problem, but would this be the case if I can make it happen by moving the mouse?

My next steps are:

- install the new RAM when it arrives
- I have a spare TOS 4.04 chip from Exxos so will probably change that at the same time.
- Try a different keyboard to see if there is a problem there - I think I can use the one from my STe????
- I shall be borrowing an old school CRT VGA monitor to see what happens with that
- I'm going to make a very basic Falcon - VGA adapter as soon as I get change to see if my Falcon doesn't like the 3 in 1 for some reason.

Any thoughts or ideas on what I'm planning, or what else I should be doing?

Many thanks,

Simon
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Re: Falcon display issues - update

Post by exxos »

It might be an idea to post your previous thread, I'm afraid I don't remember much about it and not been following a topics lately.

But I also thought you had proper GB6 results when using the proper profile ?
smoore100 wrote: Tue May 14, 2024 12:38 pm The strangest thing is when running the keyboard test from the cartridge, I can make the display 'wobble' by moving the mouse, and this is 100% replicable.
That is odd. On the older STFM machines moving the mouse could cause sound samples to run slower because the keyboard interrupts are very slow basically and prevent the CPU from running instructions.

However, as I understand it, the Falcon video is different in that it uses the videl accessing RAM directly to display the video. At that point the CPU could literally be removed from the system and the falcon should still display the video kind of thing.

I would suggest just running your finger around the CPU pins and other chips and see if you can invoke some change. I would also check that none of your chips are getting hot either. The Falcon power supply should not really start melting itself, though they do run rather hot after a while, but should not be "that" hot.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
smoore100
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Re: Falcon display issues - update

Post by smoore100 »

Thanks for the quick reply, and yes you're right I'm certain Gembench gave better results last time I tried it.

I'll take a look at the chips later on, also have the CRT monitor coming later so will also try that.

All the best,

Simon
smoore100
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Re: Falcon display issues - update

Post by smoore100 »

You know how quite often it's the simplest things that fix stuff?

14" VGA monitor taken from a server room works perfectly!

RAM access is still a little slow but I have another 14MB on the way.

Now I need to look for a CRT myself!
atari030
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Re: Falcon display issues - update

Post by atari030 »

LCD's on the Falcon can be a PITA outside of stock (VGA) resolutions because of the flexibility in Videl. Demo and game coders used to switch resolutions like crazy and LCD's will struggle to keep up with odd resolutions and have to resync often. Because the resync takes ages and the demo might change frequency just as often it ends in blank LCD.
My CT2 Falcon has all sorts of weird RGB res issues on an LCD my stock one does not have. CRT's would likely cure my problem but being space poor I just suck it up and don't worry about it. I have an original 3 in 1 as well as a Screenblaster and I think the CT2 also has its own external video clock config. its a bit of a challenge on an LCD, CRT is going to be king.
If the OS is running OK I'd doubt your ROM is an issue. Wait states, maybe. Exxos has a faster ROM you can use IIRC. RAM will definitely be affected by resolution as well. Are they out by much?
smoore100
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Re: Falcon display issues - update

Post by smoore100 »

ROM is 99% and RAM is 95% on the test I just did, which is better than last time, RAM was around 85% then.

I have more RAM coming anyway for the 14MB card, I'll leave the ROM as it is, no point changing something that is working.

I'm still going to try and find an LCD that works well with VGA though, I'd forgotten how much real estate a CRT takes up for such a small screen!

Cheers,

Simon
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Re: Falcon display issues - update

Post by exxos »

If you look at the bottom image, you could have waitstate "issues" as mentioned before.

https://exxosforum.co.uk/atari/last/FALCWS/index.htm
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
smoore100
Posts: 63
Joined: Wed Apr 03, 2024 5:45 pm

Re: Falcon display issues - update

Post by smoore100 »

Yep I'd looked at that, but not keen on soldering so will have a think about it!

Many thanks,

Simon
smoore100
Posts: 63
Joined: Wed Apr 03, 2024 5:45 pm

Re: Falcon display issues - update

Post by smoore100 »

Monitor arrived this morning, Dell U2410 - WOW!!!!

Without adjusting anything at all I get a solid VGA signal on all resolutions I could try on the Falcon - and it also handles my 8-bit machines!

£60 refurbished - an amazing deal!

I think I'll try plugging the USB power into the adapter tonight and see how it behaves with Blow Up.

Many thanks,

Simon
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