ALPHA MODIFICATIONS

All information relating to the Alpha plus all the WIP threads etc.
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PhilC
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Re: ALPHA MODIFICATIONS

Post by PhilC »

exxos wrote: Tue Sep 25, 2018 10:47 pm
Icky wrote: Tue Sep 25, 2018 10:42 pm I think you just like to keep me busy with my soldering iron
At least your keeping up, Not sure where the other 15 people have gotten to...
Me? I'd rather sensibly gone to bed :P
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rubber_jonnie
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Re: ALPHA MODIFICATIONS

Post by rubber_jonnie »

I'm waaaay behind, on account of other priorities, work, home maintenance etc.

I'm kind of at the stage now thinking I should wait in order to apply all the fixes in one go to see how it turns out!!

I've barely touched an Atari in weeks now :(

Still, winter is coming,which means I should have more Atari time!!
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PhilC
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Re: ALPHA MODIFICATIONS

Post by PhilC »

I can verify that those fixes work on my board too.

And as with Icky's my floppy doesn't want to play either.

Well done guys.
If it ain't broke, test it to Destruction.
PeteW
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Re: ALPHA MODIFICATIONS

Post by PeteW »

Forgottenmyname wrote: Wed Sep 26, 2018 5:47 pm I can verify that those fixes work on my board too.

And as with Icky's my floppy doesn't want to play either.

Well done guys.
Does your display do that periodic blanking like Ickys too or is your picture stable?

I've really enjoyed watching the progress of this from virtually no picture to a nearly functional machine in under 2 weeks :)

If I had a spare motherboard, I'd be well up for being a beta board customer!
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PhilC
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Re: ALPHA MODIFICATIONS

Post by PhilC »

I don't remember seeing it flicker like on the video.

I will try running it again a little later on and see what happens.

I'm wondering if it's a difference in monitor type?
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exxos
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Re: ALPHA MODIFICATIONS

Post by exxos »

FLOPPY FIX

Fixies missing pull ups on the LS06 buffers (never were on any schematic either!)

Solder 10K resistors to either the IC on the bottom of the PCB, or the resistors in a row on top of PCB (which ever is easier).

For example solder a 10K resistor to the highlighted pins on the resistors, then solder the free ends to 5V (tap from pin 14 of LS7406)


1772f.jpg
1772f.jpg (92.28 KiB) Viewed 6320 times
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Icky
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Re: ALPHA MODIFICATIONS

Post by Icky »

exxos wrote: Wed Sep 26, 2018 11:50 pm FLOPPY FIX

Fixies missing pull ups on the LS06 buffers (never were on any schematic either!)

Solder 1K resistors to either the IC on the bottom of the PCB, or the resistors in a row on top of PCB (which ever is easier).

For example solder a 1K resistor to the highlighted pins on the resistors, then solder the free ends to 5V (tap from pin 14 of LS7406)
Here is a photo of my quick hack to get this up and running - a cluster of resistors tied to pin 14:

IMG_3115.png
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PhilC
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Re: ALPHA MODIFICATIONS

Post by PhilC »

The stripes don't match up :P

Does it need to 1k? I'm running short on those by the looks.
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exxos
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Re: ALPHA MODIFICATIONS

Post by exxos »

Forgottenmyname wrote: Thu Sep 27, 2018 10:19 am Does it need to 1k? I'm running short on those by the looks.
No idea. I suggested 10K to Icky.. I guess almost anything would work, even 100K maybe .
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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PhilC
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Re: ALPHA MODIFICATIONS

Post by PhilC »

If you've kept up, your board should now look a little something like this :)
20180927_162013.jpg
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P.s. not done the 16mhz mmu fix as it was optional.
If it ain't broke, test it to Destruction.
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