Sidequest: VGA scan doubler

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derkom
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Re: Sidequest: VGA scan doubler

Post by derkom » Mon Aug 03, 2020 4:27 pm

Darklord wrote:
Mon Aug 03, 2020 2:56 pm
I'll *never* forget the first time I reached across a "live" 1040ST I was
working on and touched the P/S with the bottom of my forearm! :o

Forget cattle prods or shock therapy! :)
Be glad you live in a 110V part of the world. :lol:

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PaulJ
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Re: Sidequest: VGA scan doubler

Post by PaulJ » Mon Aug 03, 2020 5:21 pm

Yes, pretty happy with 110/220. When I worked for Motorola building and deploying a STB we had a contract with a telecom in Camberra AU. We found a vendor to supply a power supply capable 50-60 HZ and 110 - 240v so they claimed. Supply worked great at 110 but in AU the supply ran so hot at 240v it would melt most things the STB sat on.. End of that vendor. :dizzy:

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Smonson
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Re: Sidequest: VGA scan doubler

Post by Smonson » Tue Aug 04, 2020 12:49 pm

Small world, Canberra is where I am!

OK, so I put my previous hand-wired prototype back in the ST and it does not exhibit this gradient problem, which is good news. The difference between the boards is that the old prototype has the FPGA driving the RGB lines directly at 3.3v instead of going through a buffer. That means there's 2 possibilities, a problem with this board itself; or else a problem with these particular 74AHCT245 level converting buffers.

That's good, it shows that there's nothing inherent in the concept that can't be overcome. A hypothesis to be tested (assuming board #2 has the same problem) is that if I build one up with wire links over the buffers, it should work the same as the earlier prototype. Another hypothesis is that if I run the board in mono, it should have the same symptoms that it does in colour (since the mono signal is being routed directly to the buffer with no scandoubling or RAM activity). I haven't actually done that yet because my code changes to get BLANK to work temporarily broke mono mode. Work for tomorrow!

Pictured: prototype v2 running with the brightness and gamma turned all the way up.
vidout13.jpg
vidout13.jpg (348.85 KiB) Viewed 1118 times

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Smonson
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Re: Sidequest: VGA scan doubler

Post by Smonson » Tue Aug 04, 2020 12:50 pm

PaulJ wrote:
Mon Aug 03, 2020 5:21 pm
...building and deploying a STB we had a contract with a telecom in Camberra AU.
That was TransACT, wasn't it. Such a tragic waste of potential.

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Re: Sidequest: VGA scan doubler

Post by mfro » Tue Aug 04, 2020 4:23 pm

Smonson wrote:
Tue Aug 04, 2020 12:50 pm
PaulJ wrote:
Mon Aug 03, 2020 5:21 pm
...building and deploying a STB we had a contract with a telecom in Camberra AU.
That was TransACT, wasn't it. Such a tragic waste of potential.
A power supply running hot is indeed a waste of (electric) potential. :mrgreen:
And remember: Beethoven wrote his first symphony in C.

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PaulJ
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Re: Sidequest: VGA scan doubler

Post by PaulJ » Tue Aug 04, 2020 5:04 pm

Smonson wrote:
Tue Aug 04, 2020 12:50 pm
PaulJ wrote:
Mon Aug 03, 2020 5:21 pm
...building and deploying a STB we had a contract with a telecom in Camberra AU.
That was TransACT, wasn't it. Such a tragic waste of potential.
Sure was. Are they still in operation I hope? Spent a lot of time in Camberra, used to stay at the casino down town. People in AU are great.!!!

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Re: Sidequest: VGA scan doubler

Post by atari030 » Tue Aug 04, 2020 10:57 pm

Most Australian providers are being gobbled up by the NBN. Looks like TPG have swallowed them up a few years ago. :cry:

I spent a fair chunk of last year working in Canberra's ANU at the NCI facility rolling out the new Gadi super computer and de/recomissioning the old Raijin one. Six months slog in the NCI data centre still gives me nightmares.

I'm constantly amazed at the projects you roll out, mate. Its like magic to the natives. :-) I'd love to drop one of these into a MegaST.

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Re: Sidequest: VGA scan doubler

Post by Smonson » Wed Aug 05, 2020 9:10 am

So the background of TransACT, for anyone who wasn't around, was that it was going to be this awesome, amazing city-wide LAN all running on fibre-optic cables and connection everyone to businesses and to each other on a high-speed link. Local traffic was going to be unmetered and thus free! This was in the mid 90s so everyone was on 56k modems and it sounded too good to be true. Everyone who had internet in those early days wanted TransACT.

Then after it finally came into existence, they had moved the goalposts a lot and in silly directions. It was still going to be a fibre-optic connection, but most of it was dedicated to cable TV with only a tiny part of the bandwidth going towards the network connection. Also, you could no longer communicate with other subscribers - you had to buy your TransACT connection - which was already overpriced for what you got, and then you had to on top of that pay for an internet connection through an ISP - and there was no free local traffic. And even then, the price of the internet connections was as high and often even higher than they charged for the same plan on a 56k modem, which made no sense at all.

They went out of business a few times and always got propped up by government money, until they were bought by TPG, a big ISP. And that was the end of that.

At least my set-top-box worked pretty well and never caught fire once!

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Re: Sidequest: VGA scan doubler

Post by Smonson » Wed Aug 05, 2020 9:13 am

atari030 wrote:
Tue Aug 04, 2020 10:57 pm
I spent a fair chunk of last year working in Canberra's ANU at the NCI facility rolling out the new Gadi super computer and de/recomissioning the old Raijin one. Six months slog in the NCI data centre still gives me nightmares.

I'm constantly amazed at the projects you roll out, mate. Its like magic to the natives. :-) I'd love to drop one of these into a MegaST.
Awesome. I had many friends at ANU, it was one of the world's top ten universities back in the day. Although I personally went to budget-priced University of Canberra where the girls were prettier :lol:

Thankyou for the support, I hope I can actually get this one finished to the point where other people can benefit from it. It seems so close now!

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Re: Sidequest: VGA scan doubler

Post by Smonson » Wed Aug 05, 2020 1:00 pm

@exxos called it yet again - it was a bad connection somewhere (in one of the RAMs, I'm fairly sure)

Found when I set up monochrome mode again and discovered the problem solved.
vidout14.jpg
vidout14.jpg (368.17 KiB) Viewed 1018 times
Now it's looking great again (albeit with only 2 bits for green until I fix that joint):
vidout15.jpg
vidout15.jpg (211.48 KiB) Viewed 1018 times
My phone likes to put a glow around things so these photos don't represent real life :lol:

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