Problem with VGA on Falcon

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fidzen
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Problem with VGA on Falcon

Postby fidzen » Thu Mar 16, 2017 4:08 pm

Hi all.

I have a Falcon with CT63 and Supervidel.
It has been working great until yesterday.
When I boot the computer with the monitor connected to the SV, I get picture and all is fine.
But when I connect my monitor to the VGA out on the Falcon and boot, I get a black screen.
It seems like the computer still boots, but without picture. Same in 030 and 060 mode.
Another thing I have noticed lately is when I run compability mode on my SV, I sometimes get
a weird picture all bugged out. But sometimes it works.
So something is wrong with my Falcon, but I don't know where to start looking.

Thanks in advance.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
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Re: Problem with VGA on Falcon

Postby jvas » Thu Mar 16, 2017 4:35 pm

Is your NVRAM ok?

fidzen
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Re: Problem with VGA on Falcon

Postby fidzen » Thu Mar 16, 2017 5:29 pm

jvas wrote:Is your NVRAM ok?


I can reset the NVRAM and change settings, and it remembers the settings.
So I guess it's okay. I changed the NVRAM chip maybe 2 years ago.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
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Re: Problem with VGA on Falcon

Postby christos » Thu Mar 16, 2017 6:17 pm

Is it set for VGA or is it set for TV/RGB?
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fidzen
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Re: Problem with VGA on Falcon

Postby fidzen » Thu Mar 16, 2017 7:12 pm

christos wrote:Is it set for VGA or is it set for TV/RGB?


It's set to VGA.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
Atari 2600 4-switch Woody

fidzen
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Re: Problem with VGA on Falcon

Postby fidzen » Thu Mar 16, 2017 7:16 pm

Something I also discovered is that when I start in 060 mode and the screen connected to the SV.
If I then have the cable connected to the SV that is soldered to some points on the main board,
I get weird frequency on the screen. I can get 58Hz, 62,5Hz or 72,5Hz. If I disconnect this cable
from the SV I always get a stable 60Hz when booting. So it seems like the main boards Videl and
clocks provide unstable frequency. I tested to replace the 25MHz crystal but no improvement.
Could it be so bad that the Videl chip is broken?
As I said first, this is a problem that I have seen more and more of lately. So something has
been bad for some time, but now it's broken somehow.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
Atari 2600 4-switch Woody

fidzen
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Re: Problem with VGA on Falcon

Postby fidzen » Fri Mar 17, 2017 12:36 pm

Have replaced both the crystal U41 and the NVRAM, but still no difference.
What components are used to produce the VGA-signal in the Falcon?
I don't want to replace the videl chip if I don't have to (very difficult soldering).
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
Atari 2600 4-switch Woody

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Re: Problem with VGA on Falcon

Postby mikro » Fri Mar 17, 2017 2:05 pm

What happens if you remove the SV altogether?

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Re: Problem with VGA on Falcon

Postby fidzen » Sat Mar 18, 2017 9:19 am

mikro wrote:What happens if you remove the SV altogether?


Black screen in both 030 and 060 mode. The computer boots it seems, but with a black screen.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
Atari 2600 4-switch Woody

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Re: Problem with VGA on Falcon

Postby mikro » Sat Mar 18, 2017 10:11 am

Then you have a winner, there's surely something wrong with the original video subsystem. Hard to debug, yes.

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Re: Problem with VGA on Falcon

Postby fidzen » Tue Mar 28, 2017 4:12 pm

I received a new Videl chip from Best Electronics today and soldered it in.
The expectations was not very high when I turned the Falcon on, as I didn't
really thought it was that easy. But it was! Now it works like a charm again.
Atari Falcon, 14Mb RAM, CT60e, Supervidel, Svetlana, 512Mb RAM, 8Gb CF.
Atari Falcon, 14Mb RAM, CT63, 256Mb RAM,4Gb CF.
Atari 2600 4-switch Woody

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Re: Problem with VGA on Falcon

Postby dhedberg » Tue Mar 28, 2017 7:36 pm

Great job! Another Falcon rescued! :-)
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Re: Problem with VGA on Falcon

Postby mikro » Tue Mar 28, 2017 11:20 pm

Are you sure the problem wasn't just some loose connection to the Videl chip? It's hard to believe that the chip itself would break. But who knows... glad that it works!


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