Ticking sound Mega STE DMA

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Oldskool
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Ticking sound Mega STE DMA

Postby Oldskool » Sun Sep 27, 2015 5:01 pm

Dear Forum,

Some time ago I bought an Mega STE.

I put an 1.44 drive, FPU and a Nova card in the machine.

The machine seems to works fine.
When however DMA music and or sounds are playing the machine also outputs a ticking noise.
This ticking noise is only present when playing DMA stuff (not on YM and it is completely silent when nothing is output).
So for instance when a demo like Amiga demo 2 is playing the music sounds fine so not distorted however a very annoying random ticking sound can also be heard.
The ticking sound is present on the audio out of the video and on the dedicated audio out ports.

How could I solve this?
Is this maybe a memory issue (there are different brands and types simms present on the machine)

I hope so embody can give me some tips.

Oldskool
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Joined: Sun May 09, 2010 7:42 pm

Re: Ticking sound Mega STE DMA

Postby Oldskool » Mon Oct 05, 2015 6:02 pm

Dear Forum,

The memory was replace however it did not solve the issue.
Today during some googling I found this document:

ftp://untergrund.net/users/ggn/Atari%20 ... te0002.pdf

It describes audio distortion caused by the shifter.
The shifter in my mega STE is a revision D C301712-001. According to the document the IC U699 (under the PSU) should be disabled when rev D is present.
My mega ste is not modified (just checked). So U699 is not disabled and unmodified.
So it seems that I need to apply this mod.

Anybody in the forum have experience with this mod?

Oldskool
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Re: Ticking sound Mega STE DMA

Postby Oldskool » Sun Oct 11, 2015 5:19 pm

Today I performed the mod. The sound issue however does not change.
I have the feeling this has to do with the hardware of the mega ste itself (concept).
So probabaly all mega ste have this with certain software due to the diffrences with the normal ste.

junosix
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Re: Ticking sound Mega STE DMA

Postby junosix » Sun Oct 11, 2015 8:04 pm

Unfortunately the shifter in your Mega STE is the one that is known for this issue, you'll need to find a C300588-001 and replace the faulty shifter with that. Some standard 8MHz STEs had this shifter too so that increases the chance of finding one.
Last edited by junosix on Sun Oct 11, 2015 8:10 pm, edited 1 time in total.

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Cyprian
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Re: Ticking sound Mega STE DMA

Postby Cyprian » Sun Oct 11, 2015 8:10 pm

Oldskool wrote:So probabaly all mega ste have this with certain software due to the diffrences with the normal ste.

hmm, I never faced that issue. I can't hear any difference between STE and MSTE
Portfolio / Lynx II / Jaguar / TT030 / Mega STe / 800 XL / 1040 STe / Falcon030 / 65 XE / 520 STm / SM124 / SC1435
SDrive / PAK68/3 / Lynx Multi Card / LDW Super 2000 / XCA12 / SkunkBoard / CosmosEx / SatanDisk / UltraSatan / USB Floppy Drive Emulator / Eiffel / SIO2PC / Crazy Dots / PAM Net
Hatari / Steem SSE / Aranym / Saint
http://260ste.appspot.com/

Oldskool
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Re: Ticking sound Mega STE DMA

Postby Oldskool » Sun Oct 11, 2015 9:13 pm

Thanks for the replies.
The ticking is overall not very bad so probably i keep it as is if a fast mod is not available.
It's also software related. When the system is in 16 mhz it seems gone.
In 8 mhz with certain games it's bad.
Try obsession pinball.


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