Atari ST RGB & motherboard help

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Atari ST RGB & motherboard help

Postby iowtheme » Thu Nov 09, 2017 5:10 pm

Hi All


Just received the motherboard today from ebay now tested the motherboard.

It boot the floppy drive fine, :D
but NO display form RGB port or TV RF port :shrug:
then I have tapped the board but nothing :shrug:
but then I tapped the simm module and RGB and RF display a picture on the screen it will not stop going backwards and forward left to right on the screen :?:

I have look at the motherboard and somebody has done some soldering near to the RGB port there is a silver Square can that can be adjusted is this anything to do with the screen backwards and forward left to right.

My 1st job I will do is resolder the joints to do with the simm module maybe a dry joint.

Can anyone help me identify the board and model and I do not know if this is a 1MB version or 4Mb?

so any help is appreciated on trying to get this board back up and running


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Re: Atari ST RGB & motherboard help

Postby simonsunnyboy » Thu Nov 09, 2017 5:13 pm

This looks like an STE motherboard to me, with the extended joystick ports visible on the left.
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Re: Atari ST RGB & motherboard help

Postby Bama » Thu Nov 09, 2017 7:32 pm

At a glance, those do not look like the original simms. I can’t be certain but you may have four 1 meg Simms.

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Re: Atari ST RGB & motherboard help

Postby MiggyMog » Thu Nov 09, 2017 7:54 pm

The rolling screen is likely a SYNC issue. Prob using 60 Hz on 5o Hz screen? Or an h sync pin issue. A close up of the top and bottom at the rf modulator / monitor port where the soldering is may help the gurus diagnose the issue.
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Re: Atari ST RGB & motherboard help

Postby mpattonm » Thu Nov 09, 2017 8:06 pm

I would suspect Q406 and components around it.

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