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TJ76

Sophia on 800XL - black screen / graphics distortion

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I recently received an eagerly awaited Sophia rev C with DVI output.  Very impressed generally with the quality of display, however occasionally the screen turns black, and then recovers, but with distorted graphics and colours (see images).  Any thoughts anyone?  Do I need to perhaps remove and clean all contacts etc. or could this be something worse.  I had RGB output working fine prior to installing this, however pixel drift and general display clarity were main reasons for wanting this upgrade.

 

The GTIA chip was in a socket so this was a non invasive install.  

 

Thanks.

 

 

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Testing further with a TV connected at same time, and the RGB picture is maintained when DVI drops to black.  When it returns with distortion, a full screen re-draw (e.g. new level in Miner) turns it back to normal, but this happens every few minutes now.

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Sounds like an issue with your TV syncing with the DVI signal. Do you have another display to try? 

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27 minutes ago, DrVenkman said:

Sounds like an issue with your TV syncing with the DVI signal. Do you have another display to try? 

Thanks.  Using a Dell U2711 that's normally pretty solid.  I'll try on a couple of other screens.  Already disassembled and cleaned all contacts with Isopopyl just now, and it did it again after that unfortunately.  When it's working, it's super crisp and clear display.

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1 hour ago, TJ76 said:

Very impressed generally with the quality of display, however occasionally the screen turns black, and then recovers, but with distorted graphics and colours (see images).  Any thoughts anyone?

I've seen this before with DVI Sophias, and in all cases I encountered, the issue appears to have been caused by timing issues on the host machine upsetting the PLLs on the Sophia. If the TV and all connections are known good, try a different 74LS08 or CPU. Failing that, consult Simius. In one case, I was sent a different firmware file for the board which solved the issue.

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3 hours ago, flashjazzcat said:

I've seen this before with DVI Sophias, and in all cases I encountered, the issue appears to have been caused by timing issues on the host machine upsetting the PLLs on the Sophia. If the TV and all connections are known good, try a different 74LS08 or CPU. Failing that, consult Simius. In one case, I was sent a different firmware file for the board which solved the issue.

Appreciate your expert advice here.  Will be following your video of a Ultimate 1mb install closely in near future when the socket's I've ordered to go with it arrive, as that board is unfortunately not fully socketted.  I'm sure it'll be by terrible soldering at fault, not your guide if it all goes wrong!

 

On this matter at hand, as I had obtained a second 800xl a few weeks ago, I swapped the Sally (as the 74LS08 was soldered down, so a worse job for me).  Initially got some very odd behavior, where had worse graphics distortion on DVI AND RGB this time, and corrupted sound and failure to boot cartridge properly.  Then it stabilized and seems to be behaving.  I'm no expert, but oxidization on that chip (as didn't clean first) perhaps, and took a while to settle ?

 

Need to be elsewhere for a while, but will test more thoroughly later.  If it is the CPU that caused the initial Sophia issues, keen to understand what can go wrong with them / be wrong with them to affect the timing?  As I want the other machine back in order, I wonder if worth trying to source a replacement if I really do have a bad chip here?

 

Further observation from the initial state before I swapped the chip, when watching simultaneously on DVI and RGB on different screens; when the fault occurred and went to black then corruption on DVI, the response to joystick controls went a little laggy .  Any clue there to being on right track to fix?

 

Thanks again.

 

 

 

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11 minutes ago, TJ76 said:

If it is the CPU that caused the initial Sophia issues, keen to understand what can go wrong with them / be wrong with them to affect the timing?

It's all clock edge/timing stuff; Simius would be the best person to ask in the specific context of Sophia. There are quite a few timing-sensitive Atari upgrades which can work with one CPU and have issues with another. It's a bit of a black art, and a matter of pot luck in some cases. It's not a case of having a 'bad' chip; more a case of the 'wrong' chip. :)

14 minutes ago, TJ76 said:

Further observation from the initial state before I swapped the chip, when watching simultaneously on DVI and RGB on different screens; when the fault occurred and went to black then corruption on DVI, the response to joystick controls went a little laggy .  Any clue there to being on right track to fix?

You talk about DVI and RGB? Do you have both RGB/Component and DVI Sophias installed, or by 'RGB' are you referring to the legacy analogue video on the Atari (which is actually 'Y/C', 'Chroma/luma' or 'Composite video')? In any case: I have no idea what would cause joystick lag here. PIA handles joystick input, so you'd have to have some weird power or clock issue for the whole system to lag. But a clock issue would certainly affect video sync.

 

One key question: when you lose the DVI display, do you also lose the 'other' display?

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2 hours ago, flashjazzcat said:

It's all clock edge/timing stuff; Simius would be the best person to ask in the specific context of Sophia. There are quite a few timing-sensitive Atari upgrades which can work with one CPU and have issues with another. It's a bit of a black art, and a matter of pot luck in some cases. It's not a case of having a 'bad' chip; more a case of the 'wrong' chip. :)

You talk about DVI and RGB? Do you have both RGB/Component and DVI Sophias installed, or by 'RGB' are you referring to the legacy analogue video on the Atari (which is actually 'Y/C', 'Chroma/luma' or 'Composite video')? In any case: I have no idea what would cause joystick lag here. PIA handles joystick input, so you'd have to have some weird power or clock issue for the whole system to lag. But a clock issue would certainly affect video sync.

 

One key question: when you lose the DVI display, do you also lose the 'other' display?

Sorry, yes my posts were inaccurate - saying RGB, which it was not - I was incorrectly referring to the legacy video, which is composite.  I am using RGB cable for my ST and confused matters here.  Nothing funky like multiple Sophia types (is that even possible to piggy back them?)

 

The lag thing was weird - definitely occurred after the Sophia 'glitch', was very noticeable as sprite continued to move and fall off an edge after i had centered stick.  

 

Re the key question: when I lost DVI, I initially had a no effect on other display beside the lag.  Then the DVI returned few seconds later, but glitchy till the next full refresh (change of game level).

 

This has unfortunately gotten worse, and I know at least one thing that is wrong now:  When I returned and powered up again, there was worse corruption on DVI and Composite outputs.  By worse, I mean unusable - see attached.  Upon switching back to original CPU, this remained.  So I removed the Sophia and replaced GTIA directly.  Problem remained!  Next step, I swapped the GTIA with my other machine, and display returned to normal on composite.  Switched back, there's the problem again.  So I have a bad GTIA chip it seems.

 

 

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The good news is the Sophia I was about to say in my other 800xl it works fine, but literally glitched at point i typed that.  Original issue, went black on DVI, then returned corrupted.

 

I'm done for tonight.  

 

Anyone have tips on best place to get a GTIA for the other one? 

 

Not sure next steps for the Sophia, but the problem seems machine independent.    First was on a "rev D" board , and this one is a "rev A".

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I suppose that the blackout followed by graphics corruption indicates a drop-outs on the 3.3V power supply of the Sophia logic. There is several possibilities - damaged 5V main PSU, damaged LDO regulator, too hot LDO regulator (too high ambient temperature or too large load current), weak contacts on the socket. Have you some multimeter? Measure the voltage between ground on the MB and ground on the Sophia board (pin 3). Measure the 5V and 3.3V supply voltage on the Sophia board. Find a largest resistor (4.7ohm) near the right edge of the Sophia board and measure the voltage across it. It should be within 0.65...0.7V. Do it all carrefully because you do it on your own risk.

 

 

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On 8/29/2020 at 6:03 PM, Simius said:

I suppose that the blackout followed by graphics corruption indicates a drop-outs on the 3.3V power supply of the Sophia logic. There is several possibilities - damaged 5V main PSU, damaged LDO regulator, too hot LDO regulator (too high ambient temperature or too large load current), weak contacts on the socket. Have you some multimeter? Measure the voltage between ground on the MB and ground on the Sophia board (pin 3). Measure the 5V and 3.3V supply voltage on the Sophia board. Find a largest resistor (4.7ohm) near the right edge of the Sophia board and measure the voltage across it. It should be within 0.65...0.7V. Do it all carrefully because you do it on your own risk.

 

 

Many Thanks for your answer here @simius .  I've had only limited time since post to look into this further, however did test with multi-meter that voltages seemed to be within tolerances and stable from what I could tell, however I am no expert. 

 

Frequency of this issue occurring seems to have gone down.  The problem occurs on three different Atari 800XLs when run for various amounts of time - 30 minutes, a few hours, it's quite random, but only the first unit had the graphics corruption on return of display.  I am running a much improved composite signal on another screen, and so have been able to continue using it when this happens, and it seems more to be blackout without corruption when display returns now.  If it returns that is, as had one time where it dropped and would not return until machine had been powered off for a while.  On same machine for info I've now installed a Ultimate 1MB upgrade and removed RF modulator.  I wonder if these changes have influenced nature of behavior in any way, as it's certainly improved a little.

 

I do wonder if it could be a monitor sync issue.  This only works with my Dell U2711, i've tried it on a few others and display does not detect the signal properly . I opted for the 1280x1024 version, and wonder if that was a mistake?

 

@simius, would it be possible to change firmware to adjust resolution with USB blaster I have heard?  I do not think firmware files are posted anywhere, however if this is an option, I'd greatly appreciate file to try this / revert to how it is now in case doesn't improve matters.

 

Many Thanks in advance,

 

TJ

 

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I'm very pleased to say that this problem I had now seems resolved.  Many thanks to @Simius for providing me an alternate firmware, and to @flashjazzcat for both comments here, and the excellent information provided in your Youtube videos, of which I have watched many and has been one of my main sources of info for info on mods to my 800XL.

 

Specific info which helped I found here from around 20.50 onwards where the same problem I had was occurring.

 

 

So, after receiving the firmware, and then ordering and after a few days received a USB blaster and micro-match connector I proceeded to Source Quartus suite for the programming, and kicked off this little project last night.  Last night was actually a complete failure as I couldn't get the damn thing to detect the USB blaster, and after some major faffing with the Jtag server service,  different drivers (causing a few blue screens!), turning off driver signing on Win 10, I gave up at around 2am.  I had the idea the blaster was crap, so ordered another, and now note I got lucky and sourced the exact one used here in the video (Hobby Components).  Seems I got a dodgy £7 clone before, but the extra £3 I spent made all the difference!

 

Firmware went on with no fuss, and so far it's behaving nicely now.  

 

Now this firmware is 1280x1024 which is the same resolution I had before, however previously I could only get it to work on one of my screens.  Now with this one it syncs with another monitor it definitely didn't work with before.  Means I don't have to switch inputs on the screen I use for work, so I can flip between things more easily - double win.

 

I'll report back if anything weird continues, but I've given it a fair old test this evening so far.

 

I did have my own "Ah S*it, here we go again" moment however after putting the Atari back together, related to my recently received Side3, however I think that merits another post, as could be a bug that needs looking at in the loader.

 

 

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