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Bryan

New video upgrade coming soon!

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It could also be a clocking issue since the PAL GTIA uses 2 clocks.

 

I'm working on fixing a couple of my spare (broken) machines to see if any of them show any video issues. This is why I haven't done a new run of the boards. I'm making sure I haven't missed somethin

 

Is the fact the corruption seems to respond to the presence or absence of the rear RF shield of any problem-solving value?

 

With the shield in place the patterns/bars/dots seem to be slightly less prominent. Also, I have experimented by starting the machine with the shield in place and then lifted the motherboard clear - and dots appear immediately in response where previously they were absent. Sometimes... That is part of the problem; there is an annoying intermittency which means I cannot establish a direct cause/effect.

 

However when the identical problem manifests even after introducing a completely new environment such as the UAV then I think it must mean the root issue is somewhere further upstream from the display than the video circuitry.

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Is the fact the corruption seems to respond to the presence or absence of the rear RF shield of any problem-solving value?

Yeah, that's what it looks like- when you remove shielding near an RF connection. The fact that you're seeing distortion in the composite signal when the shielding is removed is very odd. It means something in the chain is unusually sensitive to it.

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Yeah, that's what it looks like- when you remove shielding near an RF connection. The fact that you're seeing distortion in the composite signal when the shielding is removed is very odd. It means something in the chain is unusually sensitive to it.

 

Maybe its something as amusing as that rather than malfunctioning in some way the UAV is actually rendering an especially faithful image of the corrupted display it has been handed!!!

 

Can you narrow down the areas I should be focussing on bryan? I have already replaced all the electrolyic capacitors for new ones and many of the ceramic units as well. You have mentioned the clock crystal/s might be at fault and we both suspect the GTIA chip. Is there anywhere else to look?

 

One good thing about the Atari's is, while in their day very complex there is a fairly limited number of things to go wrong by modern standards!

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Anyone try using shielded cable(s) from the GTIA to the UAV and shielded wires to the output jacks?

 

Seems logical that any unshielded wires WILL pick up stray signals and then go to the UAV, get amplified, and then more going to the output jacks.

 

The video going from the output jacks to the tv/monitor ALWAYS have shielded wires! Same goes for RF signals!

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Anyone try using shielded cable(s) from the GTIA to the UAV and shielded wires to the output jacks?

 

Seems logical that any unshielded wires WILL pick up stray signals and then go to the UAV, get amplified, and then more going to the output jacks.

 

The video going from the output jacks to the tv/monitor ALWAYS have shielded wires! Same goes for RF signals!

Question about shielded cables. The signal wire is obvious, but what about the braided shielding? Does it get connected to ground on both ends, only one end?

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When I installed the UAV in the 800XL I ran a separate ground and left the UAV ground pad intact - and what I got was some really bad banding that had moving bits during memory/SIO access... Removing the separate ground and/or splitting the UAV pad stopped that.

 

 

Well I disconnected the separate ground this morning (removed the wire from the terminal block) ... it made the vertical bands somewhat less prominent but they're still there, especially during RAM access. Interestingly, this effect was NOT present prior to reinstallation of my U1MB board. So later today, I think I'm going to reconnect the separate ground and split the pad on the UAV board. If that doesn't help, I'm going to run a separate +5V line to the board.

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Well I disconnected the separate ground this morning (removed the wire from the terminal block) ... it made the vertical bands somewhat less prominent but they're still there, especially during RAM access.

 

It was a startling difference when I made the change, and the U1MB was present the entire time in my case.

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It was a startling difference when I made the change, and the U1MB was present the entire time in my case.

 

 

Okay, I reconnected by separate ground wire and cut the Ground pad on the UAV board (and thanks for that design feature, Bryan) and now my picture is very much improved. I still get some RAM access noise however. I think tonight or tomorrow I will try a separate +5V power lead to the board and see if that changes anything.

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I've installed the UAV in my 130XE and I can see much improvement -especially for text. Last Word 80 column text is actually easily legible. I used Bryan's recommended XE install method and output is S-Video. BTW I also read the instructions as running the signals through the ferrite beads, not after. I am still getting the dreaded vertical interference pattern but not as badly as before. I should note that I have the old Newell 1Meg ram module installed and no shield. Fortunately my LCD has a noise reduction option which has all but eliminated the banding. I did have one minor problem with the install, the T-6 connection on the terminal block didn't work - I had to solder the color-in lead directly to the board. But all-in-all I'm pleased with the UAV, and I want to extend many thanks to Bryan for a very nice mod!

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I did have one minor problem with the install, the T-6 connection on the terminal block didn't work - I had to solder the color-in lead directly to the board. But all-in-all I'm pleased with the UAV, and I want to extend many thanks to Bryan for a very nice mod!

 

I ordered batches of 6-pin terminals from 2 different sources and one style was definitely better than the other. On some of them, you need to push the screw downward as you turn it so it doesn't back out the top. After it's cycled a few times, it's okay. Also, if the screw fails to close the clamp, you can stick a small object into the clamp opening and lift it up so the threads catch again. For all future units I'm going to order the ones that worked better.

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I ordered batches of 6-pin terminals from 2 different sources and one style was definitely better than the other. On some of them, you need to push the screw downward as you turn it so it doesn't back out the top. After it's cycled a few times, it's okay. Also, if the screw fails to close the clamp, you can stick a small object into the clamp opening and lift it up so the threads catch again. For all future units I'm going to order the ones that worked better.

 

I would suggest you try right-angle pin headers - although I guess then you would need dupont sockets and a crimper to attach the input and outputs.

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I would suggest you try right-angle pin headers - although I guess then you would need dupont sockets and a crimper to attach the input and outputs.

 

 

Yep, something I've yet to purchase given how rarely I connect things to headers. I would hate to tell someone to go buy 100 sockets for $2 on eBay in order to make 4 - 5 connections, and also, oh by the way, a $15 - $20 crimper that they may never need again. I mean, it's always nice to add another tool if you think you might need one in the future, but personally I'm glad Bryan went with a terminal block.

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Yep, something I've yet to purchase given how rarely I connect things to headers. I would hate to tell someone to go buy 100 sockets for $2 on eBay in order to make 4 - 5 connections, and also, oh by the way, a $15 - $20 crimper that they may never need again. I mean, it's always nice to add another tool if you think you might need one in the future, but personally I'm glad Bryan went with a terminal block.

 

I've yet to find a crimper that I am happy with - a solid handset with comprehensive set of dies can be £80+ (eBay Auction -- Item Number: 2521486301921?ff3=2&pub=5574883395&toolid=10001&campid=5336500554&customid=&item=252148630192&mpt=[CACHEBUSTER])! However, in my experience you do get the lowest profile and most secure joints that way, short of just soldering the wires in to the through-holes on the UAV.

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If you've fitted Ultimate 1MB, you should be no stranger to Dupont connectors, crimping, etc. Right angle headers take up less vertical space than the rather large terminal block, so each has its advantages, I guess. It would also be expedient to simply supply a set of Harting connectors (terminals and housings) if going down that road, since they are indeed as cheap as you say. ;)

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The real trick is learning to position the wire and pin so that everything is exactly where you want it when you squeeze (especially when doing a wide ribbon where you can't just substitute a messed up wire).

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If you've fitted Ultimate 1MB, you should be no stranger to Dupont connectors, crimping, etc.

 

I cheated - I had a set of pre-fab jumpers from RPi hobby stuff - pins on one end, sockets on the other. I simply pulled the pin connectors off one end and soldered that end to the board for the U1MB install. :)

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So latest install (attempt) in the 2600. I seem to be getting rather clear B/W composite video (when B/W switch is set to B/W) but switching it to color I get a heavily banded B/W image. The xrgb won't lock on either signal. I had the wires soldered to resistor points, but moved them directly to the chip for testing, same results.

 

Can anyone spot what I did wrong? :)

 

 

4dCtl1.jpg

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So latest install (attempt) in the 2600. I seem to be getting rather clear B/W composite video (when B/W switch is set to B/W) but switching it to color I get a heavily banded B/W image. The xrgb won't lock on either signal. I had the wires soldered to resistor points, but moved them directly to the chip for testing, same results.

 

Can anyone spot what I did wrong? :)

 

 

 

http://atariage.com/forums/topic/246613-new-video-upgrade-coming-soon/?p=3413565

 

Try lifting pin 6 of TIA.

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Small rant:

 

I really hate working with LCD monitors. My main PC monitor (A Samsung P2770HD) is also a TV with a composite input. It looks like ass with old systems in my opinion, but it's my reference for LCD testing. Today I was doing some work with an 800XL/UAV and suddenly I had chroma lines all over the screen. I started tearing everything apart and checking my wiring. I yanked out the UAV and stuck another one in. I fired up the scope and started looking for funky signals. Eventually I thought to put just the LUMA signal into the composite input and everything looked perfect. So, I get out another unmodified 8-bit and try it. Sure enough, same obnoxious chroma bands. It appears my monitor has decided to turn off the chroma trap. I'm looking for some way to reset it or something. This has been a weird day.

 

EDIT:

Well, resetting my monitor didn't help. I checked it on my other LCD TV and it looks perfect.

 

-Bry

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So I had a few minutes today so I cut the +5V pad on the UAV and soldered in a separate power lead - I pulled from the positive side of C3 (the electrolytic cap immediately to the right of the 800XL power jack), as shown in the instructions for Bryan's earlier "Quick & Easy 800XL video mod", http://atariage.com/forums/topic/41580-quick-easy-video-upgrade-for-800xl/page-1 (which I did with great results on my other 800XL).

 

After running the separate +5V lead, all of the dreaded vertical lines are gone when the system is idle. There is a very tiny bit of noise during certain CPU/RAM operations such as compiling a short Action! program or something, but substantially less than there was before. As soon as I track down a TV with S-video or a monitor with chroma/luma, I'll check it again.

Edited by DrVenkman
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So I had a few minutes today so I cut the +5V pad on the UAV and soldered in a separate power lead - I pulled from the positive side of C3 (the electrolytic cap immediately to the right of the 800XL power jack), as shown in the instructions for Bryan's earlier "Quick & Easy 800XL video mod", http://atariage.com/forums/topic/41580-quick-easy-video-upgrade-for-800xl/page-1 (which I did with great results on my other 800XL).

 

After running the separate +5V lead, all of the dreaded vertical lines are gone when the system is idle. There is a very tiny bit of noise during certain CPU/RAM operations such as compiling a short Action! program or something, but substantially less than there was before. As soon as I track down a TV with S-video or a monitor with chroma/luma, I'll check it again.

 

You might also try moving the ground wire to someplace right next to the DIN jack and see if it helps.

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You might also try moving the ground wire to someplace right next to the DIN jack and see if it helps.

 

 

I tried soldering the ground wire straight to the ground pin of the DIN jack - no change, alas. Is there a better location? With a bit of further testing, most if not all of the remaining interference seems to be during SIO operations. I'm almost coming to the conclusion that this particular board rev (rev C) is just noisy.

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