Booting Atari Falcon without VIDEL?

[jamesrhq]

I've got a Falcon PCB I've been meaning to look at repairing for a while now and it's missing the VIDEL. Before trying to put a VIDEL on the board I'd like to see if it's got any life in it. Does the Falcon boot (via diag cart) ok without VIDEL? Looking at the schematics I don't think it's generating any clocks. It does act as the SDRAM controller, though, so any memory access will fail.

Has anyone any experience in debugging from this point?

[jamesrhq]

A little more looking over this board. Pins 3&4 of U52 and U24 have been cut and soldered together. After some digging this appears to be related to some kind of accelerator install? And U7 is missing! Didn't spot this at first. Just the SCSI controller, though, so shouldn't cause an issue booting from diag cart.

Although now it looks like this may be a botched accelerator removal. I can see quite a few clock traces have been cut but then restored. This should be fun.

[alexh]

I doubt very much if anyone has tried to boot a Falcon030 without a VIDEL however I imagine there are threads where people have had ones that had broken VIDEL that needed to be replaced. Anyone had any experience with that and the Diagnostic cart?

I would imagine it would start to boot with a broken videl. (depending on other issues)

This is the install guide for the most famous bus accelerator the Phantom, maybe work backwards?

https://atari-wiki.com/index.php?title=Phantom

This is the Nemesis another one

https://atari-wiki.com/index.php?title=Nemesis

Have a look around

https://atari-wiki.com/index.php?title=Accelerators

[jamesrhq]

I believe you were right with the Phantom, I've looked at the install doc and everything mentioned in there seems to have been touched. Most of the mods had been reverted, but a some remained (shorted UART legs).

Once I've got the GAL's replaced (parts on order) and given everything a thorough check over I'll try and boot it. I think it should boot the diagrom cart as that's very eary on in TOS. Will report back! :)

[jamesrhq]

Hah, funny story, I’d put off looking at this board for a long time because I thought someone had been at it and made a bit of a mess installing the wrong size capacitors around the audio section. While searching the service manual for the correct components to install to tidy it up, I found references on the web to different mods made in this area. I then checked my other working board and it looks the same! :lol:

So it looks like the messy bodge work was Atari! The rest of the board actually looks really clean with no damage other than cut (and subsequently repaired) traces to do with an accelerator install. The only thing which was removed a bit hackily was the realtime clock, some pads pulled. I spotted the SCSI chip was removed too. All makes me wonder why this board ended up as parts. Maybe the VIDEL got damaged and the owner never got a new one and just ended up using it for spares?

The only thing I’ve spotted so far which was ‘wrong’ was the keyboard acia had the rx and tx clock legs shorted but also connected to the PCB. Although I have a feeling it was just pin 3 connected to the PCB and then 4 shorted to it, which I think is valid. Otherwise I was a bit concerned about the tx clock from COMBEL being shorted to the rx clock. The midi acia rx and tx clocks are connected anyway, so no issues there.

Is there a list of all the different mods made to the falcon PCB revisions?

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