shear_xear

Well the same problem occurred with the third UAV board. I know I have installed the UAV on three 7800’s with the expansion port, but these are the first two that were fully socketed.

The two I have used while troubleshooting I received about two weeks ago. I did just get a few more yesterday, but they could be from the same batch as well. I will try one of them out just to be sure. I do know that the UAV I used to check if the problem carried over to a second board worked perfectly with a later revision board, so there is definitely something about this revision that is causing this.

Well I swapped in some original 7800 switches and it’s still there. The only other thing I can think of (other than it being the version of 7800 board) is that it is the batch of UAV? There definitely wasn’t any issue through the RF.

Well.... I received another fully socketed Rev A 7800 yesterday and tested it out. There was no flickering through the RF output and everything looked great. Then I swapped in the new board and got the same flickering problem. I had recapped and replaced the PR and the Power and Reset switches. I went back and reinstalled the original caps and PR and still have the flicker. Could it be the switches causing this, because otherwise there seems to be something in this revision that doesn’t like the UAV. I really don’t want to pull those new switches off if there is no way that’s the problem. Any thoughts?? Thanks!

Well, the fact that the same UAV kit worked without problems on a different board, and a second UAV kit had the same issue with the problem board and also gave a perfect picture on a second board, it seems unlikely it is the mod kit itself, unless this specific version of the board is just incompatible with the UAV kit.

It did have the RF output before the mod, but that was removed during modding. I am not sure if this happened before the mod as I only loaded the game up to the second screen briefly to verify it worked. I would guess that it did have the problem as the UAV takes the image from the same source (I think). The RF image is so muddy in comparison I would have needed to really pay attention to the image displayed to notice it (wish I had).

Unfortunately this happens when using composite too. Actually it’s worse when the composite is being used. I have removed and then replaced all of the UAV leads as well and had the same results.

I actually have tried two power supplies and had the same results. I think it is somehow power related as well, but finding the source of the problem is becoming a pain. Thanks!

There’s no chance it could have anything to do with the 7800s color balancing pot?

So new TV. Same. Replaced the buffer. Same. Swapped in a different Maria. Same. I even ran everything off the resistors to the UAV just to be sure. This is the second one of these early 7800s that has some weird issue.

The Maria was the first one I swapped. I will try another Maria just to be positive there. Like I said, I have seen this before to a lesser degree with the simple mod, but probably only two times in four or five years, so out of dozens of 7800’s.

Okay, so it’s definitely the 7800. The new UAV gave the same results. 2600 games look great. I also already swapped out every socketed IC on the board (which is everything including RAM and BIOS) just to be sure those were all good. Which of the two ICs is the buffer (or is it both)?

I have a another UAV so I will swap it in and see what happens. Thanks!

For some reason the videos don’t seem to show up. Odd. As far as other games, Ballblazer and Asteroids are wonky too. Donkey Kong Jr seems fine. Those are the only others I have tested so far.

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Hi. So I disconnected the T col lead and it did the same thing. Here is a picture the install and a video of what is happening. Thanks! IMG_8469.MOV

Hi everyone! I have an Atari 7800 which I have installed a UAV mod on, and when I went to test the mod the 2600 games looks great, but when I turned on Pole Position II there is a flickering horizontal “rainbow” that seems to be interference of some kind. I had recapped the three caps and replaced the power regulator. I’ve noticed this before on previous composite mods with the “simple” mod kit, but it is more pronounced with the UAV. I did check voltage across the board and everything appears normal. Anyone have any ideas what might be happening here?

It’s the third “dead” 7800 I’ve been able to revive this week. Definitely the one I’ve had for the longest, and one with the expansion port to boot!

I checked continuity to pin ten and that was good so I replaced the diode and voila! Everything works perfectly. Thanks for all the help!

Awesome. I will check out the diode and capacitor. Hopefully it’s one of those. Thanks!

Hate to bring this one back up again, but I dragged this one back out to see what I can find. What I found was that when checking continuity with pin three on the right player controller jack (the one that would pull left automatically) it showed continuity with pin one of the RIOT (ground). As I can’t see how pin three runs out to the RIOT (there is no trace that I can find) any hints where I might look to fix this? Thanks!

Yes, sorry, the transistor. Actually I rechecked and now it is 12v powered off and 10v powered on. The power supply is a C0244471 with the silver label on it. Like I said before though the same psu is giving me right around 9v on every other 7800 board.

So I replaced the 4013 and that did nothing to remedy the problem, but then I swapped out the transformer next to the power jack (with the circular opening) and the system now powers on and off correctly. It is still getting 12v when powered on at the jack and the 2200uf cap and power regulator, but the regulator drops it down to 5v, and all of the ICs showed 5v as well. Will this damage the console or wear the PR out, or can the board handle this? Thanks!

Oh, and I got right at 9v in and 5v out at the regulator on the other boards...

I will look at the 4013. The power supply gives me right around 9v on every other board I tested it on last night, which was about six as I’m going through all my “bad” boards with a UAV to see if I can get them going again. Thanks!!