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-^Cro§Bow^-

UAV - Ultimate Atari Video - Atari 7800

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Correct. You generally want a bare board for a 7800 or 2600. I *think* the kit might work for a 5200 but still requires you to piggy back on the 4050, but I’m not 100% sure. I’ve installed a bare board in one of my 2600’s but not in a 5200 or 7800 yet.

I actually get the kit for the 5200 use. I do not get them preassembled though because to keep it all more low profile I like to just solder in the jumper connections myself instead of using the actual jumper pins and headers. But the kit is nice for the green terminal block to easily attach for wiring and for the sockets that I would heavily advise using when installing into a 5200.

 

But for 7800 use you only need the basic kit that is correct.

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So I removed the unnecessary 4050 socket pins and configuration headers, installed my spare UAV into my 7800 with -^Cro§Bow^-'s execllent illustrated guide from the beginning of the thread and ... it doesn't work. Alas. I appare to have killed the UAV with my surgery. I verified +5V and ground to the UAV, verified continuity of every signal from the resistor ladder on the 7800 to the appropriate point on the UAV, and even pulled out my 'scope to verify that those signals are making it to the pickup points on the UAV. But there is absolutely no video output of any kind, verified with the 'scope. No composite, no luma, no chroma. I confirmed this with both 7800 and 2600 carts. Drat.

 

I did not remove the RF modulator so I've at least confirmed that the 7800 still works. And I confirmed that the audio portion of the mod is installed properly - both TIA and POKEY sound come through perfectly balanced. So now I have a 7800 with RF video but no audio, and line-out audio but no composite or S-video, lol. :P

 

So it looks like I'll need to order a new UAV after all.

Edited by DrVenkman

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Are you sure the UAV is dead? I've had at least one UAV that arrived not working right. found out one of the buffer encoders on the UAV didn't have quite enough solder on it because I got a picture when I pressed down on it. Just had to throw some flux on the pins and hit them with some heat of the iron.

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Are you sure the UAV is dead? I've had at least one UAV that arrived not working right. found out one of the buffer encoders on the UAV didn't have quite enough solder on it because I got a picture when I pressed down on it. Just had to throw some flux on the pins and hit them with some heat of the iron.

 

Yep. It worked before my surgery to remove the configuration jumpers and socket adapter.

And so it goes. At least it's not a super-expensive board. I've got a new one headed my way next week after the holiday so with luck I'll be up and running next weekend.

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I just tried a UAV install this weekend, and it ended up not working for me. Got a few gray bars, then nothing. I checked continuity between the board and the 7800, and everything seemed to be a-ok. I even checked to see if I accidentally created a solder bridge, and that didn't seem to be the case. RF still works (picture wise, anyway). I followed the PDF at the beginning of the thread - is there a common problem or rookie mistake that I may have made?

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I just tried a UAV install this weekend, and it ended up not working for me. Got a few gray bars, then nothing. I checked continuity between the board and the 7800, and everything seemed to be a-ok. I even checked to see if I accidentally created a solder bridge, and that didn't seem to be the case. RF still works (picture wise, anyway). I followed the PDF at the beginning of the thread - is there a common problem or rookie mistake that I may have made?

Post some pics of your installation work. Also make sure you were attaching the wires from the resistor ladder to the inside set of vias on the UAV and not the outside set.

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And now that this has come up and we have two instances of UAVs not working having followed the guide at the beginning of this thread...

 

Is there something I should change to make it more concise? I'm happy to make new pics etc... There are a few things I do differently now with actual UAV installs on the 7800s sent to me for work but I've never considered them to be critical to getting the UAV functional.

 

Still I'm more than open to any ideas and suggestions on how to make this guide easier to follow or change as others might think is needed?

 

Thanks guys and really let me know what I need to change on this process?

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I’m reasonably sure that my install only failed because I had to do surgery on my fully-assembled UAV board to remove the socket adapter and configuration headers. The instructions were clear and the photos made it easy to follow along. The only thing I’d change is to re-do the audio installation to the later method shown in one of your videos to avoid cutting the RF audio output.

 

Now if I receive my new UAV later this week and it still doesn’t work, I may have to amend my thoughts. :P

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I've thought about redoing it because of the audio part as well. But then if most people are removing the RF modulators completely, then the method shown is still totally valid. But that is a good idea all the same and not that tough to add in. I will have to take some pics of that section close-up on the next 7800 that comes my way for a UAV. Although I might actually be caught up on that now that I think about it at the moment?

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Crossbow,

 

The vid on YouTube you did was great and made things really straight forward. At the end you showed the completed mod but not the external connector process - any pics/explanation of that would be great.

 

I'm going to get one shortly - have a in VG condition 7800 that shows only in B&W (though the 2600 side is in color). Haven't really touched it yet - so not sure what might be the issue. Also intend on recapping it when I add the UAV.

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Crossbow,

 

The vid on YouTube you did was great and made things really straight forward. At the end you showed the completed mod but not the external connector process - any pics/explanation of that would be great.

 

I'm going to get one shortly - have a in VG condition 7800 that shows only in B&W (though the 2600 side is in color). Haven't really touched it yet - so not sure what might be the issue. Also intend on recapping it when I add the UAV.

 

I didn't show the external connectors because that is very subjective and the way I do them isn't how they have to be done. Especially since I tend to install the AV out jacks in probably the most difficult place you can on a 7800 LOL!

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Still I'm more than open to any ideas and suggestions on how to make this guide easier to follow or change as others might think is needed?

 

 

I'm fairly certain that it's just that the UAV is very small, and my soldering skills are only slightly above beginner. But I'll get those pics of the install so we can figure out what exactly went wrong and I continue to improve my skills!

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I didn't show the external connectors because that is very subjective and the way I do them isn't how they have to be done. Especially since I tend to install the AV out jacks in probably the most difficult place you can on a 7800 LOL!

 

No probs! Very nice job though!

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My UAV arrived a day early so I decided to go ahead and install the new UAV. Worked perfectly! (Good to know I can still follow clear, perfect instructions! :P )

 

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I've only wired up composite for now; I may or may not add an S-video jack at some point - we'll see. Composite it just about perfect for my gaming preferences.

 

Anyway - to reiterate, the PDF instructions in post 1 are perfect if you don't mind losing audio through RF. If you want to keep RF audio, there are two resistors to install in the audio circuit - I'll leave that to -^Cro§Bow^- to go into if he likes. :)

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Here's my hatchet job of soldering the UAV in. I feel pretty good about the joints I made on the 7800 board itself, but the UAV is just so much tinier than what I'm used to, so it has a few little scars on it. I used a 3.5mm stereo jack for the composite video and mono sound signals, using a 3.5mm to RCA cable to connect to the television.

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Just before I order - these work ok for PAL also??

 

While I haven't installed a UAV into a PAL 7800, I would imagine it would work. I state this because literally the same wire connections are used on the Magic Knight board. So I would try and following Magic Knight's S-video PAL install instructions and sub the various connections from those in place of where they are needed on the UAV. Now my only concern would be that some resistance values might be different etc so I've not idea how it would look. But again, they use the same video taps for their signals. I can tell you that Bryan who originally designed the UAV did so specifically with NTSC in mind at the time.

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Here's my hatchet job of soldering the UAV in. I feel pretty good about the joints I made on the 7800 board itself, but the UAV is just so much tinier than what I'm used to, so it has a few little scars on it. I used a 3.5mm stereo jack for the composite video and mono sound signals, using a 3.5mm to RCA cable to connect to the television.

 

 

I don't see anything immediately wrong here but some of the angles are hard to make out on the actual luma signal wires on the UAV. Do you simply get nothing at all? Do you even get a blink on the screen when powering on etc? It does look like maybe that third pin from the top on the left hand side of the 74xx IC under the trimmer pot might not have enough solder on that leg? I can't tell, but I can tell you I ran into that exact same issue a few months back with a UAV I received. Only on that one I think I was getting a scrambled picture and I discovered by accident that when I pressed on the UAV trying to look at my wiring work it suddenly started working. So I figured out pretty quick that one or more of the legs on that 74xx IC wasn't making contact. I just threw some flux on there and put some solder on the tip of my iron and touched up those pins. Worked fine after that.

 

If you lived closer I'd be happy to look at it but shipping from New York can be expensive.

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Okay, here's an amateur #Protip for setting your MARIA color pot (the top one) while you've got the machine open for your UAV installations -

 

Pop in a relatively common title like XEVIOUS - if your title screen is muddy brown, adjust to get a rich green. Similarly, when you're playing, the background should be green and the paths sort of golden-brown. If you're too out of whack, the forested areas will be brown and the paths tending toward pink (!), at least on a decent CRT.

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Ok - so I fiddled around a little more with my 7800, and I noticed something strange. I have the CV signal going into an AV switchbox, which is then going through an RF modulator. I tested switching back and forth between other sources on my switchbox, and when I would switch back to my 7800, the image I was looking for briefly flashed on my screen before it flickered back to nothing. Do you suppose that the video signal isn't strong enough to trigger the RF modulator?

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While I haven't installed a UAV into a PAL 7800, I would imagine it would work. I state this because literally the same wire connections are used on the Magic Knight board. So I would try and following Magic Knight's S-video PAL install instructions and sub the various connections from those in place of where they are needed on the UAV. Now my only concern would be that some resistance values might be different etc so I've not idea how it would look. But again, they use the same video taps for their signals. I can tell you that Bryan who originally designed the UAV did so specifically with NTSC in mind at the time.

 

Thanks CrossBow! Ordered one so will check that out when it arrives!

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Ok - so I fiddled around a little more with my 7800, and I noticed something strange. I have the CV signal going into an AV switchbox, which is then going through an RF modulator. I tested switching back and forth between other sources on my switchbox, and when I would switch back to my 7800, the image I was looking for briefly flashed on my screen before it flickered back to nothing. Do you suppose that the video signal isn't strong enough to trigger the RF modulator?

 

I’m confused - you’re running composite video out to an external RF modulator? Why mod the machine at all then?

 

Have you tested the composite signal straight into the composite input of a TV without the intervening devices?

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I’m confused - you’re running composite video out to an external RF modulator? Why mod the machine at all then?

 

Have you tested the composite signal straight into the composite input of a TV without the intervening devices?

 

The current CRT I'm using is a stopgap until I get one with better inputs (still waiting on a good deal for a 20" Trinitron). Also, the picture will be improved regardless due to skirting around the finicky RF switchbox that the 7800 uses.

 

Haven't tested straight input, but I will as soon as I am able this weekend.

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The current CRT I'm using is a stopgap until I get one with better inputs (still waiting on a good deal for a 20" Trinitron). Also, the picture will be improved regardless due to skirting around the finicky RF switchbox that the 7800 uses.

 

Haven't tested straight input, but I will as soon as I am able this weekend.

The UAV is specifically designed to maintain as close to a perfectly-spec’d Composite video signal as is possible. Bryan’s scope traces in the two big UAV threads show that his design nails this about as close as it is humanly possible for an analog signal source. I’d be very surprised if your A/V switch is having trouble locking onto it, but going direct into a TV would be the best way to be sure.

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Are people saving the RF modulators to repair 7800s in the future? I ran into that on a Coleco that needs the RF to work to Mod the video. No RF = no video.

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