Atari Falcon ECO - Sound Crackle During DMA Playback

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rj1
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Atari Falcon ECO - Sound Crackle During DMA Playback

Postby rj1 » Tue Feb 14, 2017 7:58 pm

No idea if this was brought to attention before?

Atari ECO on DMA sound issues, mentions removing/shorting DMA clock (CPUCLKA) inline resistor R221 and removing C208, both near the Combel (C208 is underside the board.)

This action also is a reason for a new PCB and schematic revisions, details in the ECO.

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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby mikro » Tue Feb 14, 2017 10:03 pm

I've always lived in impression what the cracks are caused by lack of a clockpatch?

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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby rj1 » Wed Feb 15, 2017 7:59 am

You are right, there are 2 more Atari documents on installing clock patch for sound issue.
Wonder which method is the "latest" one.
Obviously they were trying different solutions.

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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby wongck » Wed Feb 15, 2017 11:32 am

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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby rj1 » Thu Feb 16, 2017 12:54 pm

Yep, but has anyone actually tried simply removing the C208 before?

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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby exxos » Thu Feb 16, 2017 1:42 pm

10pF value, it would hardly do anything. Technically it should be a small snubber for the clock to stop ringing. , clock resistors I think were 33R, so 33R plus 10pF... Basically a RC filter/snubber. R21 should be a 33R or there abouts also. I would check on a scope and see whats going on there. Its a long clock run from where the clock patch is installed normally.. such a long trace will have a lot of ringing on it.

There was a guy who had all sorts of cracking noises on his Falcon, he used my clock patch and reported all the problems went away. Can't just think who it was now though.
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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby rj1 » Thu Feb 16, 2017 1:55 pm

Yes I do believe your solution helped people with this. I'm just curious as to this particular official Atari fix. I have some cracking noise under Ace Tracker so going to try this myself.

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Re: Atari Falcon ECO - Sound Crackle During DMA Playback

Postby exxos » Thu Feb 16, 2017 2:08 pm

rj1 wrote:Yes I do believe your solution helped people with this. I'm just curious as to this particular official Atari fix. I have some cracking noise under Ace Tracker so going to try this myself.


Ahh yep, I think Steve I am think of posted on here about problems with ACE tracker.

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