dostrow

Any tips on what to try next, the system is running a brand new 74LS08 purchased from Mouser and I'm happy to order a 74F08 and try it if you think this gate might still be the problem. I'm trying to avoid a wild goose chase as most of the chips on the 130XE aren't socketed, outside of GTIA which I socketed to install a SOPHIA and the 74LS08 at your recommendation the only other socket on the system is under ANTIC and was clearly done at the factory.

Well my saga is not over, it has started to misbehave again and only works 1 out of 5 or so boots, when it doesn't work I usually get a blank screen but sometimes get a messed up SIDE3 loader screen that eventually freezes. The next vexing thing is that I spent some time today getting the 800XL I have working again (it has no U1MB) and tried the SIDE3 in it and in the 800XL it works 100% of the time. I've tried several other carts in my 130XE beyond the DigDug I got and they all work just fine... So now I'm lost and don't know if I should be RMAing the SIDE3 or what even to try next.

Welp...I got it working....and how is somewhat annoying. I had purchased a new power supply from lotharek when I bought the U1MB and the SIDE3. The moment it came in the mail I switched to using it exclusively. When I switch back to using the original power supply from the mid 80s...everything works. Swap out to the power supply I bought from lotharek and the cart no longer is detected.

I got the sockets in today and swapped the 74LS08 out with the one that was in the 800XL carcass I have (the original was a Mitsubishi 74LS08, the one I pulled from the 800XL was a TI) but it exhibits the same behavior. I have nothing left but to assume that the hardware issues that @Candle referred to have affected me. This is the last day of vacation for @lotharek so once he is back I'll get the RMA process started, I've already sent him an email for when he returns. Thanks for all the help to both of you in troubleshooting.

Perfect! Thanks for the info. I don't currently have any 14 pin sockets on hand so ordering those right now (gotta love Amazon Prime). Also going to just get a few brand new 74LS08s from Mouser while I'm at it just in case the one in the 800XL carcass that I have is questionable. Will report back based on what I find.

Taking a look at the 74LS08 on my board (it is a Rev. B board with the bodge wires connecting pin 8 to a via between GTIA and ANTIC and pin 10 to pin 15 on the 74LS138 next to it, these seem pretty standard for all the pics of Rev. B boards out there...) the only other notable things are that pin 9 had a GIANT solder blob on it on the top of the board (which I removed with my desoldering gun, to no effect) and pin 9 and 10 are jumped on the bottom of the board with solder, given the flux residue this was clearly intentional, unsure if like the bodge wires this was standard practice but jumping the two inputs to the third gate of this chip sure seems odd. I haven't been able to find any pics of the underside of this board but at least in Rev 4 (which also lacks the bodge wires) those pins are not connected. I have a spare 74LS08 sitting in a dead 800XL that I could scavenge but I want to make sure I understand exactly what of these changes I am supposed to re-create after replacing the chip.

I got my hands on a known working Dig Dug cartridge and it works perfectly, lunching both with SDX disabled and by typing CAR in SDX. This tells me pretty conclusively that it is the SIDE3 cart itself. I take it this is something I am going to have to take up with @lotharek once he is back from vacation. Unfortunate as sending stuff back and forth from Poland to Texas is less than awesome. Is there anything else I should be trying before then? My Fujinet is supposed to be arriving this weekend in case that helps get data to the system at all...

For what it is worth when holding down the button on power up (with SDX disabled) it drops me right to BASIC (which I suppose is the correct behavior for that). Unfortunately at the moment I don't even have any SIO devices (though there is a Fujinet on it's way). I'm also going to try and get my hands on a known working cartridge of some other nature to verify that loading any cartridge works as expected.

No worries at all, I understand completely that it is a new product that you are clearly still ironing things out with, nothing is perfect at launch, its the price early adopters pay, I totally understand. I'm also more than happy to return this for a replacement to lotharek once he is back from vacation if we can determine that it is faulty. To remove the U1MB from the picture I went ahead and put the original ROM and MMU back in place, made sure the system was booting back to the original BASIC ROM just fine and then shut the system off, put the SIDE3 in the cartridge slot and attempted to boot it, again just a black screen, no luck. The two things I cannot isolate (yet) are: 1). Does this 130XE properly load any cartridge? I purchased it off eBay at roughly the same time I bought the U1MB and SIDE3 from lotharek and it didn't come with any carts so I really can't say for certain, all I can say is that it passes all the built in tests, both with and without the U1MB installed. 2). The only additional upgrade this system has is a SOPHIA DVI rev. C. I have not tried removing it to see what happens there...

I am running the default XL OS and with SDX disabled I get the same behavior, it boots to a black screen. Interestingly I tried one other thing which was inserting the cartridge while in the U1MB settings screen. When doing this the screen gets all scrambled and the system locks up, no further keyboard input works.

I have tried with and without the card. It is a 16GB SanDisk. The only other indications from the cart are a brief flash of the green LED when the system is powered on if the cart is inserted prior to doing so and a flash of the screen when the cart is inserted post power on.

@flashjazzcat I just unwrapped my new SIDE3 and tried this on my 130XE with U1MB (I bought both the U1MB and SIDE3 from lotharek a few weeks ago and just got around to getting things going last night) but when I get to step 6 I just get a black screen, I only have the 130XE and the SIDE3, no other gear as I am just starting to collect. Any thoughts on what I might try? The U1MB otherwise seems to work. Edit: To clarify, after typing CAR and hitting Return I get the black screen, SDX starts up just fine.