Falcon H-sync fault

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exxos
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Falcon H-sync fault

Post by exxos »

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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Re: Falcon H-sync fault

Post by exxos »

Comparing my Hsync with the faulty machine..

My test machine
ve.png
ve.png (3.44 KiB) Viewed 4625 times

Faulty machine.
v1.png
v1.png (3.29 KiB) Viewed 4625 times

So looks to me like the Video is faulty as I am tapped right into pin 3 on it... :roll:
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SolderGirl
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Re: Falcon H-sync fault

Post by SolderGirl »

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 »

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 :(
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Re: Falcon H-sync fault

Post by exxos »

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

hsn.png
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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.
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Re: Falcon H-sync fault

Post by exxos »

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

https://www.exxosforum.co.uk/forum/viewt ... =17&t=1698
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People should find solutions to problems, not find problems with solutions.
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