Degraded video quality with 1040 STF (C070523-001 REV.D)

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rubber_jonnie
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by rubber_jonnie » Wed Sep 05, 2018 3:22 pm

exxos wrote:
Wed Sep 05, 2018 1:36 pm
sandord wrote:
Wed Sep 05, 2018 1:19 pm
I'm thinking of making the CO70789-001 REV. C1 my favourite motherboard, since it has the best features:
The CO70789 type are my favorite styles. Versions without the modulator (STF) are same board, even ones with SMT DRAM, basically same board. So really any similar style board of the CO70789 should be a good one.
Also my favourite boards too, the ability to upgrade the RAM relatively easily, and also the Blitter, make it a good board to get up to a decent spec.

The only trouble I had was that some I've run into have the vias filled with solder, so you need to desolder before you can upgrade anything! 340 holes to desolder isn't fun.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

KyleB
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by KyleB » Wed Sep 05, 2018 4:11 pm

What's the story behind these weird boards? I've had single side drive 1040s that didn't have them, and neither did any of the 520STFMs with rainbow TOS that've passed through my hands. Seems they showed up for a bit in the middle and then went away again.

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exxos
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by exxos » Wed Sep 05, 2018 5:36 pm

KyleB wrote:
Wed Sep 05, 2018 4:11 pm
What's the story behind these weird boards?
No idea. There does seem to be rather a lot of them. Even the CO70789 with its revisions, while they look the same, I found the MMU can be like 1cm to the left on one revision than another.. bizzare..
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.

tzok
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by tzok » Fri Sep 07, 2018 1:36 pm

On mine I did this (it is not perfect, but much better):
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by exxos » Fri Sep 07, 2018 1:41 pm

tzok wrote:
Fri Sep 07, 2018 1:36 pm
On mine I did this (it is not perfect, but much better):
What did you patch wire up ?
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.

tzok
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by tzok » Fri Sep 07, 2018 3:08 pm

5V rail... from the main cap near PSU connector directly (almost - via the factory choke coils) to Shifter, MMU and DMA, and I've added a 100nF cap under the Shifter.

SolderGirl
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by SolderGirl » Fri Sep 07, 2018 3:25 pm

tzok wrote:
Fri Sep 07, 2018 3:08 pm
5V rail... from the main cap near PSU connector directly (almost - via the factory choke coils) to Shifter, MMU and DMA, and I've added a 100nF cap under the Shifter.
Did that improove the quality?
I also have those vertical stripes on my 520 STm.

tzok
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Re: Degraded video quality with 1040 STF (C070523-001 REV.D)

Post by tzok » Fri Sep 07, 2018 3:32 pm

I've got a lot of signal phase variations, which were visible on a VGA monitor in ST-High, these wires helped to minimize this effect, and the stipes on color modes also disappeared. But I still have a problem with first 10-15 lines being noisy and "skewed" in HIGH mode. I found that the video signal is very dependent on 5V rail, increasing or decreasing voltage on this rail by 100mV results in shifting the whole image by 1-2 pixels left or right. I also have to mention that I have no PSU for this unit, and I'm using really cheap PSU from a 3,5" USB disk enclosure (but I've also tested it on lab supply with more or less same issues). I've ordered a MeanWell RT-65B PSU...

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