Shakes

Yes, the 5V is present on the appropriate pins of both U38 and REG1. I don't think this is a power issue as the unit powers on each time. I'm more inclined to think it's audio or video related as that seems to be the oddest of the behaviors. Like I mentioned, it will work eventually, but may take 100 tries. The other weird thing is about 5 of those 100 there is video, but no audio, but that doesn't get passed the boot screen. Meaning, no roar, no letter falling sound, then freeze. I played it last night without the shell and bumped Tom & Jerry, the RF modulator, and all the other chips to test for any loose or cold solder joints. Game stayed running without a hitch. I'm wondering if one of the crystals are failing, but I don't know what that behavior would look like.

Without the right tools? A nightmare and you will probably damage the board. With them, not difficult, but the right tools aren't cheap unfortunately. The ground plane on these boards is huge, so it takes some real heat to get this board up to the right temp to start, and there's like 10 ground pins in that connector. I wouldn't rule it out, but I've inspected it pretty thoroughly and can't find anything. There was a few that were suspect, and if you look closely at the bottom picture of the board, you can see where I reflowed some joints outside of the aforementioned spots. I had a similar thought, which is why I turned to the dynamic components, but even after playing it for hours, as soon as you turn it off and on again, it could take a full 100 tries before it worked successfully again. So odd. I'd rather it never worked then worked the way it does, as that would explain more than such intermittent behavior. Appreciate everyone's ideas. Adds perspective I may not have thought of. Cheers!

The LED lights bright each time, but I also replaced the two large power capacitors, C174, and C142 on the power side to check. No change. Checked all the others capacitance levels and they all are within spec. I hate not knowing what's going on with this thing, as I've spent many hours scouring the forums looking for solutions with little to show for it. The best I can come up with such a random issue is a dynamic component failure, but I've swapped the cart connector, switch, and RF modulator, all with the same results.

So I have a Jaguar that looks new inside and out. It powers up, but the dreaded black screen. Occasionally, it will show the Jaguar loading screen, and sometimes completely loads the game. It will freeze at the boot logo without sound most times it does boot. It does work 1 out of 100 boots and plays fine when it does, so I know T&J are fine. I have played 3-4 hours without issue. If I turn it off though, this starts the cycle all over again... Troubleshooting so far: Checked the power capacitors Cleaned the cartridge connector, which had pins that were a little stretched, but swapped it out just in case Cleaned the power switch, but swapped it out to test as well Tried multiple games (Cybermorph was still in the original unopened plastic), same results Tried OEM psu and Genesis model 1 psu, same results Tested RF modulator and composite soldered to the board, same results I'm at a loss on where to look next. Unfortunately, I don't have a scope just a DMM, nor a second Jaguar to help troubleshoot, and am hoping someone here has experienced this before. The board is super clean as you can see, no corrosion or anything that's seen in my microscope either. I don't know what would allow the system to boot completely every 100 times, but only load the Jaguar screen maybe once every 20 times. Generally, if I hear the roar when I turn it on, it will completely boot. No roar, it will have no sound and perform the loading animation and freeze after the ATARI drops.

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It's the same one (TG vs Atari branded). The power supply itself is a 1/8" as mentioned. Check the tightness with a set of headphones. Still lose? -> Replace the jack - https://console5.com/store/atari-2600-vcs-dc-power-jack.html Tight? -> Look at a replacement power supply