Which 1040 STF is this?

[32bitminus]

Waiting for this to arrive, I was trying to figure out which model this is, has a floppy with a smaller button. All the 1040 STFs I can find have the larger floppy button. Did I get a fake? Will find out once I tear it down! Suppose a flopy drive was replaced and cover could have been swapped...

I know Atari is famous for tons of revisions.

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[tzok]

Later models had same floppy like STes, so it could came out from the factory in this shape (well, not shape, but configuration). So it is the late US (120VAC/60Hz !!!) version.

[rubber_jonnie]

Just a later model IMHO.

I have an STF too, and it's a big button model, best thing to do is have a look at the mainboard revision, it may have a data on it, and you can then see what type/revision it is. Also get sysinfo.prg run on it so you can see what version of TOS it has plus all the other useful info.

Also, does the box match the STF inside it? If I recall the box may have the serial number on it and the model marked.

[32bitminus]

Thanks folks. Will be getting it today so if I have the time will open it up. I am getting the box with it too. Owner claims he knows nothing about it as it was his grandfathers and in a shop covered up for 25 years. Was sold in unknown Condition. Have no clue how you could type with that keyboard cover!

Looks like it has had a mod at some point as there is a drilled hole right where the RF lead would go....

Hope to get this bad boy going 💯

[rubber_jonnie]

Looks like it has had a mod at some point as there is a drilled hole right where the RF lead would go....

I'd pay some consideration to the PSU when you open it up, particularly the condition of the caps, and you may wish to consider a set of replacements to get it nice and stable. I'd also advocate completely removing the mainboard and removing it from the metal shields, just to check for corrosion and other stuff on the underside of the mainboard.

Sounds like maybe the previous owner may have had plans to try and add a modulator, so it'll be interesting to get some photos from you for the motherboard revisions section of the forum https://www.exxosforum.co.uk/forum/viewf ... ?f=41[url][/url].

[32bitminus]

So ripped into the bad boy, first thing thing didn't looks so hot, CPU has a socket soldered on top of it, and and closer inspection, looks like pins clipped to by pass the CPU... I am not sure but guessing some sort of later CPU upgrade or blitter add on? I am guessing now the hole in the back was to enable and disable that. It has been removed :( Need to find out what those pins do.

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Closer inspection around the board I see two things that look like mods, under the board their is a resistor across some pins I think for the monitor port. And under 1 chip looks like a jumper? In the second photo, it is the one just above the A marker to the right.

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So the last thing is the TOS roms, they are all labled Mega TOS and one of them is a EPROM?

IMG_20190221_132221.jpg

I was looking for a little bit of a soldering project was not expecting this fraken-weenie! First things first, I need to get video out of this, since it is missing the components here I think I need to get the resistor and transistor that go in here in order to get composite sync? That way I can get a VGA monitor on this and see if it even powers up to the desktop. Where can I source these parts and the numbers list.

Then I guess I will decide if I need to pull the CPU, Socket it, put in a new one, and also replace the TOS ROMS. Other than the shield and the small hole case is in excellent shape with little yellowing, so I think it is worth saving!

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This board is a revision D1, Mods if you want to move this thread to the hardware trouble shooting, guess that would be more appropriate. I can upload good shots for the mobo section if this one is missing too.

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[32bitminus]

Just a later model IMHO.

I have an STF too, and it's a big button model, best thing to do is have a look at the mainboard revision, it may have a data on it, and you can then see what type/revision it is. Also get sysinfo.prg run on it so you can see what version of TOS it has plus all the other useful info.

Also, does the box match the STF inside it? If I recall the box may have the serial number on it and the model marked.

Box and serial # match.

[32bitminus]

Looks like it is pin 13, the BR pin on the CPU that was clipped and repaired, that seems to be a BUS Request pin, for off board devices to request access to the bus.

[Atarian Computing]

Being an STF, it's missing the modulator circuitry intentionally. Otherwise it would be an STFM. You can still get video out from the 13-pin DIN connector. The modulator involves more than the few apparent components. I wouldn't bother with that in this day and age anyway.

[32bitminus]

Being an STF, it's missing the modulator circuitry intentionally. Otherwise it would be an STFM. You can still get video out from the 13-pin DIN connector. The modulator involves more than the few apparent components. I wouldn't bother with that in this day and age anyway.

Thanks, I was not talking about Composite Video, but Composite Sync. The circuit takes the H and V lines from the board and makes the appropriate sync signal for VGA spec monitors. Atari's monitor can take separate H and V sync with the RGB and does not need this.

From what I read around, on an STFM pin 2 is Composite Video, on an STF it is either NC or Composite Sync, the ones that have composite sync look like this:

Screen Shot 2019-02-21 at 3.09.48 PM.png

Mine is missing those 6 components for the Composite Sync. I don't have easy access to an Atari or other monitor that can deal with seperate sync signals. Finding a parts list has been troublesome so far.