The UAV Rev. D Video Upgrade Thread

[rmzalbar]

Is there something non-standard about the way the Atari 2600 syncs? After installing the UAV mod and using the composite output:

 

 - My CRT television shows a "flag-waving" horizontal distortion effect in the top 10% of the screen with bright playfields

 - Most of my CRT monitors lose sync for a frame or two on bright color flashes

 - Two of my monitors, both JVC A13SU, fail to sync vertically at all with the 2600 (rapidly rolling picture.)

 

These things don't occur with the RF output. This is on a four-switch 2600, all five lines taken from the TIA socket. Any ideas?

 

Edited May 16, 2020 by rmzalbar

[+DrVenkman]

That's weird - I've got UAV boards inside a 4-switch 2600, a 7800, and a 5200. None of them have issues like that to my CRTs. It looks like your TV seems to find the colorburst too "hot" to display properly. 

[rmzalbar]

I reimplemented this because my placement of the UAV turned the RF into a snowstorm. Now the UAV is under the top shield and I'm tapping the signals from the resistors instead of directly at the socket. I'm also getting 5v and GND from somewhere else instead of from the RF's power supply. This cleaned my RF up just fine, but nothing changed with the composite issues I've described.

 

I scoped the TTL signals to the UAV and the video output and they LOOK fine. Maybe someone will recognize these symptoms and tell me where to look in my TV or otherwise. Since it's affecting at least two different devices, I'm inclined to believe the Atari is a little bit non-standard.

[_The Doctor__]

those pictures indicate CRT issues...

 

it can be for a number of reasons, I'd make sure capacitor are good in the drive and amplifier circuits of the crt...

 

If the video amplifier clips before cutoff is reached then the beam will not be blanked completely and you will see a lighted background with slanted retrace lines. Some video amps will also show a bad recovery time from clipping to black, this may lead to black streaks after black images. If cutoff voltage rises due to some unexplained wear or because VG2 rises (due to drift or sometimes due to owner intervention by turning the Screen potentiometer) the user may compensate for the increased  brightness by lowering the brightness control of the set. Some televisions automatically lower the brightness of each channel because they have automatic cutoff control. Either way, the cathode voltages rise and clipping may occur with retrace lines as a result.

 

Tearing and other issues will manifest... you can do a number of things to help this out... re-capping, alignment, re calibration... and in some cases... what was once called CRT zapping/heating/rejuvenation.

 

here.... a quick run down... you'll find more specifics if you dig...

 

https://www.repairfaq.org/sam/crtfaq.htm

Edited May 17, 2020 by _The Doctor__

[rmzalbar]

The mod does looks good aside from the sync issues. It's perhaps not as color saturated as the RF with the chroma boost, but it's very bright and clear.

 

I'm very glad I was able to keep the RF and the chroma boost circuit. While I was at it, I added an RCA jack for RF so I could finally ditch the hardwired RF cable. I really hate those hardwired cables. After a bit of work with some copper tape in the RF area of the board, even the RF is looking better than ever.

 

I will order up an S-video bulkhead jack and also an RG8 F-type bulkhead jack to replace the RCA RF jack I installed today, as I noticed that I did get a slightly cleaner picture when I plugged CATV coax straight into the board during testing.

 

I went through the CRT repair faq, and the only thing that seemed to resemble my issue was sync loss on bright screens being a common issue related to inadequate filtering on the sync splitter in the TV itself. I'll check into that when I have nothing to do for a day.

[+DrVenkman]

4 hours ago, rmzalbar said:

It's perhaps not as color saturated as the RF with the chroma boost, but it's very bright and clear.

Wait, is this a 4-switch with the 820 ohm color saturation boost mod? If so, Bryan’s original thread for the Rev C UAV warned users to remove that resistor, as it would interfere with the UAV’s output. 

[MVladimir]

On 4/6/2020 at 8:04 PM, MacRorie said:

Thanks.  That was corrected a bit ago.  The manual is now on version 1.8.  If anyone finds any other errors or suggestions, please send them along. I have included a copy here for folks.

......

 

TBA UAV Manual.pdf 38.85 MB · 26 downloads

You attach here version 1.7 !

Where we can download last current version?

(On TBA site I find only v.1.62 of February 20, 2020 .....)

Edited May 17, 2020 by MVladimir
Text edit

[+MacRorie]

5 hours ago, MVladimir said:

You attach here version 1.7 !

Where we can download last current version?

(On TBA site I find only v.1.62 of February 20, 2020 .....)

Well, huh.  Sorry about that.  I have fixed the ones listed on thebrewingacademy.com Here is the most recent version (1.81)

 

 

UAV_manuals.zip

[rmzalbar]

7 hours ago, DrVenkman said:

Wait, is this a 4-switch with the 820 ohm color saturation boost mod? If so, Bryan’s original thread for the Rev C UAV warned users to remove that resistor, as it would interfere with the UAV’s output. 

It is, but I followed Bryan's advice from the manual by moving the boost to the opposite side of the decoupling capacitor.

[rmzalbar]

Well this is interesting, I encountered this issue again today when I built a composite output circuit for Odyssey 2. This time though, I had it on a scope AND I had an output level potentiometer. There was a ton of DC bias so I ran it through a capacitor and then gave it a schottky clamp to bring the sync level up closer to ground.

 

Anyway, so what was happening? While tuning the output level, I adjusted the level up too high, the sync level got blown up to nearly meet the black level and bingo, sync problems and that same flag-waving effect. I'll have to take another look at the Atari UAV output now.

Edited May 18, 2020 by rmzalbar

[+DrVenkman]

3 hours ago, rmzalbar said:

Anyway, so what was happening? While tuning the output level, I adjusted the level up too high, the sync level got blown up to nearly meet the black level and bingo, sync problems and that same flag-waving effect. I'll have to take another look at the Atari UAV output now.

Good that you have some data now. If you haven’t already, you might want to read Bryan’s very first UAV thread, the one that resulted in the first (Rev C) production version. Lots of good info in there about the basic UAV design goals, how he went about achieving them, etc. 

[MVladimir]

On 5/17/2020 at 10:50 PM, MacRorie said:

Well, huh.  Sorry about that.  I have fixed the ones listed on thebrewingacademy.com Here is the most recent version (1.81)

 

 

UAV_manuals.zip 97.29 MB · 14 downloads

Thank you !!! Hope you can add version number to filenames and posted archives with UAV manuals. This solve a lot of questions...

Anyway thank's !

[dee.rog]

Apologies if I missed this info in a thread somewhere.  Any ideas on how best to find someone to do the UAV mod to a 2600?  (I'm in the Atlanta area.)  I have no soldering skills, though I'd like to learn, so I don't want to tackle this yet.

[rmzalbar]

On 5/18/2020 at 4:51 AM, DrVenkman said:

Good that you have some data now. If you haven’t already, you might want to read Bryan’s very first UAV thread, the one that resulted in the first (Rev C) production version. Lots of good info in there about the basic UAV design goals, how he went about achieving them, etc. 

None of the usual video mods for the Odyssey 2 gave me good results. I ended up designing my own from bits and pieces of amplifier examples I found on the web. It was an eye-opening experience.

 

The Solarfox mods work okay, but they are emitter-follower which, although a stable and predictable option, provides no voltage amplification and in fact puts out a slightly dimmer picture than the source due to diode drop in the transistor. It also strips all DC bias from the signal, which not every display is happy with.

 

The only way I could get a stable, bright picture on all displays under all conditions was to use a two-transistor amplifier with a pot for DC bias and a pot for amplification. I needed a small positive bias with a well-defined sync level and 0.7v from black level to white.

 

I will check the UAV output again, now that I know what works.

 

 

Edited May 21, 2020 by rmzalbar

[rmzalbar]

Here is a scope capture of my video signal from UAV. This is at the far end of the composite cable, measured across a 75-ohm resistor termination in lieu of being plugged into the TV.

 

It looks like the sync tip is not nearly low enough, less than half the amplitude it should be, relative to blank. The colorburst even slightly exceeds it. Everything else looks like it's about the correct scale, with full white about 1 volt above blank.

 

This is definitely the cause of my weak sync issues. Is there something external to UAV that could affect this, perhaps in getting the sync signal out of the Atari video circuit to the UAV? This is a 4-switch 2600.

 

For comparison, I can replicate the same symptoms from my Odyssey 2 console by detuning its home-made composite amplifier so that it clips the sync signal too close to the blank level the way this one is.

 

My symptoms are that all of my displays have some amount of sync instability, with some of them not syncing at all. Worse with brighter screens.

 

Edited May 21, 2020 by rmzalbar

[+DrVenkman]

22 minutes ago, rmzalbar said:

Is there something external to UAV that could affect this, perhaps in getting the sync signal out of the Atari video circuit to the UAV? This is a 4-switch 2600

I don’t think so. I have a UAV in one of my own 4-switch 2600’s. It’s a rev C UAV board, so not *quite* the same as the current rev D, but I have no issues like that. I also have a rev D UAV inside one of my 7800’s and again don’t have any sync issues with 2600 games.  

 

This is my 7800 displaying a gray bars test pattern from a 2600 diagnostic cart ROM running on my Harmony Cart, measuring luma and chroma. I should repeat the test on my 2600 at some point but I would expect normal results on a 2600 to look similar. 

 

[+KylJoy]

One of my TVs has issues with a UAV Rev. D installed in a 7800.  I'd love to alter/modify it in order to get this particular TV to sync to it.

[rmzalbar]

22 minutes ago, DrVenkman said:

I don’t think so. I have a UAV in one of my own 4-switch 2600’s. It’s a rev C UAV board, so not *quite* the same as the current rev D, but I have no issues like that. I also have a rev D UAV inside one of my 7800’s and again don’t have any sync issues with 2600 games.  

 

This is my 7800 displaying a gray bars test pattern from a 2600 diagnostic cart ROM running on my Harmony Cart, measuring luma and chroma. I should repeat the test on my 2600 at some point but I would expect normal results on a 2600 to look similar. 

 

 

I haven't tested with S-video yet (I don't have a DIN jack for the console.) Curious if that would change anything since the colorburst is separated from the luma signal. However, I can see in your screenshot that you have a much deeper sync level than mine, with the sync level peak-to-peak about double the amplitude of the colorburst.  It looks much more like the final tuning I arrived at for the Odyssey 2.

Edited May 21, 2020 by rmzalbar

[+DrVenkman]

I wonder if your UAV has a component that’s not soldered cleanly or something? Or your sync signal isn’t being picked up properly? Have you examined the UAV closely for damage or defect? They are made by machine, of course, so it’s possible there was an assembly issue.

[rmzalbar]

58 minutes ago, DrVenkman said:

I wonder if your UAV has a component that’s not soldered cleanly or something? Or your sync signal isn’t being picked up properly? Have you examined the UAV closely for damage or defect? They are made by machine, of course, so it’s possible there was an assembly issue.

That did occur to me. I was wondering if Bryan might pop in and say "Oh dear, you seem to have a dry joint on a pre-amp bias pin.." or somesuch. I'll crack it open and take a good look.

 

I do also have two other UAVs destined for the A8s, but those are of the plugin type so there will be a bit of farting around getting one connected to the 2600.

Edited May 21, 2020 by rmzalbar

[Awch]

I just want to post a small cautionary tale so that others can learn from my stupidity... If you find yourself beating your head in frustration because you are convinced you've installed your UAV correctly but, no matter what you do, you can't get a picture to appear on screen... sit back... take a deep breath... examine the UAV board... and make sure it doesn't say "r.C"!!!... Ugggh...

 

If you do find yourself in the same situation and need the Rev. C jumper settings, this post is your friend: 

 

Take care everyone!

Greg

[+slx]

44 minutes ago, Awch said:

 examine the UAV board... and make sure it doesn't say "r.C"!!!... Ugggh...

 

 

Take care everyone!

Greg

You're not alone. Been there, done that . Sorry for not posting a warning myself. 

 

It would be great to include the Rev. C settings in the latest revision of the manual (as a footnote or appendix) as a service to future hackers who might happen across an older board. It took me quite some time to find that info.

[irwinpks]

On 2/1/2017 at 2:02 PM, Frankie said:

That did it. Nice color!!

 

So what does that strange jumper that I had to go diagonal from 2 pins not next to each other do? I can remove it and I don't notice any difference.

Hi Frankie,

I've been following you and Bryan in this thread...I also have an Atari 800 and got the UAV kit version.  I don't get a display at all...just can hear a click from the speaker and kindly ask for some guidance.  The board I have is revision D.  I've attached the jumper header layout for an 800 configurations (see attached).  To note, I didnt' jumper the diagonal as indicated.  It was mentioned that this handles the GTIA to provide 16 shades...instead of the 8 that we should get if i did this minimum install.  There are 4 wires running from the green terminal.  The 2 opens slots are ground and not running to anything.  I'm assuming the GND on top of the board is where I attach a lead and then send it to a spot marked on the board (from Bryan's manual), and the 2 GND on the terminal of the board is not needed.

 

The 4050 chip is not installed.

 

When I power on the system...there is no flicker on the screen.  I musta missed something.  Could you assist please?

 

Post edit...the last pic flashes on the screen after 1.minute for 30 secs and cycles again.

 

Thank you in advance,

 

Irwin

Edited August 18, 2020 by irwinpks
Added pic

[+MacRorie]

1 hour ago, irwinpks said:

Hi Frankie,

I've been following you and Bryan in this thread...I also have an Atari 800 and got the UAV kit version.  I don't get a display at all...just can hear a click from the speaker and kindly ask for some guidance.  The board I have is revision D.  I've attached the jumper header layout for an 800 configurations (see attached).  To note, I didnt' jumper the diagonal as indicated.  It was mentioned that this handles the GTIA to provide 16 shades...instead of the 8 that we should get if i did this minimum install.  There are 4 wires running from the green terminal.  The 2 opens slots are ground and not running to anything.  I'm assuming the GND on top of the board is where I attach a lead and then send it to a spot marked on the board (from Bryan's manual), and the 2 GND on the terminal of the board is not needed.

The grounds on the green terminal strip are the grounds for your video out.  The manual recommends the Kit version of the UAV and you have the A8 plug-in variety.  Although we can make it work, it will be a little trickier.

 

The most obvious problem is that you have the UAV in backwards.  Pin 1 on the UAV should be oriented to pin one of the 4050 socket.  There is a pin one indication on the UAV (see the small back semi circle at the top), If that is unclear, there is a picture in the manual that will aid in orienting it correctly.

 

1 hour ago, irwinpks said:

The 4050 chip is not installed.

 

When I power on the system...there is no flicker on the screen.  I musta missed something.  Could you assist please?

 

Post edit...the last pic flashes on the screen after 1.minute for 30 secs and cycles again.

 

Thank you in advance,

 

Irwin

 

 

 

The UAV *should* be okay once you orient it correctly, but it depends on the voltages going to the wrong pin.  Try changing the orientation and then backchannel me.

 

-M

[irwinpks]

5 hours ago, MacRorie said:

The most obvious problem is that you have the UAV in backwards.  Pin 1 on the UAV should be oriented to pin one of the 4050 socket.  There is a pin one indication on the UAV (see the small back semi circle at the top), If that is unclear, there is a picture in the manual that will aid in orienting it correctly.

 

The UAV *should* be okay once you orient it correctly, but it depends on the voltages going to the wrong pin.  Try changing the orientation and then backchannel me.

 

-M

SUCCESS!! I rotated the board 180...shown below.  Also took before and after pics of Centipede.

 

Thank you MacRorie!

Edited August 18, 2020 by irwinpks