derkom - Progress

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derkom
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Re: derkom - Progress

Post by derkom » Thu Jul 25, 2019 5:12 pm

Now we get to the fun part, where I have probably mucked things up. Opting not to bother with an un-f*ck board, I've attempted to rewire the video output on the board. I looked at the un-f*ck PCB layout and attempted to duplicate the rerouting myself ...
IMG_20190725_185521.jpg
IMG_20190725_185521.jpg (66.13 KiB) Viewed 323 times
IMG_20190725_185532.jpg
IMG_20190725_185532.jpg (45.49 KiB) Viewed 323 times
After doing this, I tried to power up the board for the first time (realised later I probably should have been testing it all along, since obviously none of the fixes on this board was repairing a fatal problem, but live and learn...). When my monitor (Dell 2001FP, 15 kHz-capable) did not seem to receive any sync, I started thinking about my rewiring and entertaining the idea that I'd gotten the whole port reversed, mirror image. So I swapped the hsync and vsync connections (above photo is after the swap), figuring even if the rest of the port is also reversed, I'd probably at least get sync on the monitor. No joy.

So that's where I am at the moment. Nothing explodes when it's powered up, but there's also no real sign of life. However there is *something* alive, because this is what I'm seeing on the vsync output ...
IMG_20190725_190940.jpg
IMG_20190725_190940.jpg (50.21 KiB) Viewed 323 times
So, I'm still pondering what's going on, and what may still be wrong. (Something is certainly wrong with the monitor output now, since I've swapped hsync and vsync and nothing else, but I don't currently know which parts are wrong.)

Depending on where this goes from here, I may just move on to a Rev. H board. ;D

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PhilC
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Re: derkom - Progress

Post by PhilC » Thu Jul 25, 2019 5:21 pm

Mine had a missing Vsync due to a manufacturing defect.

So best advice I can give us to trace the video signals back from their sources with a multimeter and the scope. As soon as I made the connection my screen came to life. *Well, after getting the syncs swapped over.

Btw, if using something like a UBE VGA adaptor, you need to have 12v available too.
If it ain't broke, test it to Destruction.

derkom
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Re: derkom - Progress

Post by derkom » Thu Jul 25, 2019 5:36 pm

PhilC wrote:
Thu Jul 25, 2019 5:21 pm
best advice I can give us to trace the video signals back from their sources with a multimeter and the scope.
Yeah, that is what I plan to do. It's going to be a bit of a learning process for me, because I have always been more of a software person than a hardware one, so I honestly don't really know what I am doing here. :roll: But of course I am keen to learn or I wouldn't be here.
Btw, if using something like a UBE VGA adaptor, you need to have 12v available too.
No, it's just a straight through cable, ST on one end, VGA on the other. Obviously this requires a compatible monitor, and the older version Dell 2001FP is one such monitor. I have verified on the Falcon that it displays ST Low successfully.

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exxos
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Re: derkom - Progress

Post by exxos » Thu Jul 25, 2019 5:40 pm

Have you done all the mods like this one ?

viewtopic.php?f=19&t=1185#p9963

Either way it may be best to go though the whole thread an double check everything is done correctly.
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derkom
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Re: derkom - Progress

Post by derkom » Thu Jul 25, 2019 6:10 pm

exxos wrote:
Thu Jul 25, 2019 5:40 pm
Have you done all the mods like this one ?

viewtopic.php?f=19&t=1185#p9963

Either way it may be best to go though the whole thread an double check everything is done correctly.
Yep, hsync fix is shown at viewtopic.php?f=64&t=1253#p11488

I've double checked everything, but triple checking never hurts. But the first thing I need to do is go back over the video out very carefully, because it's definitely not right the way it is right now.

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