Falcon H-sync fault

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exxos
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Falcon H-sync fault

Post by exxos » Thu Sep 06, 2018 1:58 pm

Never seen this before...






Looking at H-sync it seems to jump down voltage, which seems to be when the monitor goes out of sync.. no idea what would cause that though ?

h_sync.png
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4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Falcon H-sync fault

Post by exxos » Thu Sep 06, 2018 2:15 pm

Comparing my Hsync with the faulty machine..

My test machine
ve.png
ve.png (3.44 KiB) Viewed 782 times

Faulty machine.
v1.png
v1.png (3.29 KiB) Viewed 782 times

So looks to me like the Video is faulty as I am tapped right into pin 3 on it... :roll:
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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SolderGirl
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Re: Falcon H-sync fault

Post by SolderGirl » Thu Sep 06, 2018 5:06 pm

Might be a bad chip.
But, is there a pull-up somewhere in this signal path?
I can imagine that a broken pullup could look similar

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Re: Falcon H-sync fault

Post by exxos » Thu Sep 06, 2018 5:41 pm

SolderGirl wrote:
Thu Sep 06, 2018 5:06 pm
But, is there a pull-up somewhere in this signal path?
I can imagine that a broken pullup could look similar
No pull ups, I tried one just to see what happened, and no change. So looks like a blown output :(
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Falcon H-sync fault

Post by exxos » Thu Oct 18, 2018 3:06 pm

New Videl fitted and H-sync has a much better output now...

hsn.png
hsn.png (3.34 KiB) Viewed 525 times

Unfortunately the odd sync issue persists :(

I have poked everything on the board, heated it up, frozen it to death, and cannot really find anything wrong anywhere. It acts like there is a bad connection somewhere.

I am going to put it down to another screwy issue by Atari. It could may well take a long time to trace as the fault is intermittent from a few seconds to a few minutes.

I am not going to spend any more time on this, as I have had this Falcon for months now for starters. Tracing these odd faults would likely take a epic amount of time which I do not have. Tracing these screwy faults is something I have spent a lot of time doing already on the STF/E already, I really don't want to start tracing these types of fault on Falcon's as well.

"Give it up as a bad job" as we used to say in my old workshop.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: Falcon H-sync fault

Post by exxos » Wed Mar 20, 2019 10:34 pm

This may have actually been cured... Please see this thread...

viewtopic.php?f=17&t=1698
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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