GabeShack Posted February 4, 2021 Share Posted February 4, 2021 Hi All, I’ve recently worked on an Atari 400 and 800xl and installed the new Sophia 2 chips with dvi connections. Both are outputting great video now. My 400 had some issues at first running cartridges but after a few tries and cleaning some carts off it worked. My 800xl is another story though. I can’t get a single cartridge to start. Ones that I already tested as working on the 400 do not work on the 800xl. I ran the self test and all items pass. Wondering how to test the cartridge slot itself. I did use some canned air to blow out the port as well as a little 99.8 isopropyl. Anyone have any thoughts to verify if the cartridge slot is working? Are there any continuity points I can check from the cartridge pins? Any suggestions appreciated. GabeShack Quote Link to comment Share on other sites More sharing options...
+orpheuswaking Posted February 4, 2021 Share Posted February 4, 2021 What carts are you trying? There are a handful that wont work on the 800XL (although I doubt that's the issue) Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 4, 2021 Author Share Posted February 4, 2021 Thanks for the reply, Ive tried most of the carts in the picture attached. Since I'm not sure which work with the 800xl I figured Id try them all. So far it only boots to the "Ready" blue screen or the self test if I hold option. Quote Link to comment Share on other sites More sharing options...
+orpheuswaking Posted February 4, 2021 Share Posted February 4, 2021 If star raiders isn't working then the cart port isn't working for sure. Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 4, 2021 Author Share Posted February 4, 2021 So if thats the case how do I fix or test it? Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted February 4, 2021 Share Posted February 4, 2021 Did the 800XL in question work with carts before you installed the SOPHIA? Can you post closeup photos of the slot connector itself? Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted February 4, 2021 Share Posted February 4, 2021 This may help with continuity checks from the Cart Port to the IC's that control it (U2 and U3) Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 4, 2021 Author Share Posted February 4, 2021 Attached are close ups of the cart port and the bottom of board with the cart port connections Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 4, 2021 Author Share Posted February 4, 2021 Im not sure if it worked before the sophia 2 since i didn't have an older monitor to test with. I'm almost through continuity testing and so far its all matching up...so Im now wondering if its a bad U5 OS ROM chip possibly since the basic chip is working to load the Ready screen. Quote Link to comment Share on other sites More sharing options...
BillC Posted February 4, 2021 Share Posted February 4, 2021 1 hour ago, GabeShack said: Attached are close ups of the cart port and the bottom of board with the cart port connections It looks to me like many of the cartridge port pads have very little solder and could be corroded. IMO resoldering all the cart port connections is recommended. Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 4, 2021 Author Share Posted February 4, 2021 Thanks for the suggestion. I’ll resolder them and try again. However it seems like all the points are showing continuity based on the schematic above but still worth a shot. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 5, 2021 Share Posted February 5, 2021 If that doesn't work, try replacing the PIA Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 5, 2021 Author Share Posted February 5, 2021 Can I use a PIA from one of my spare Atari 400s or is it specific to the 800xl? Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted February 5, 2021 Share Posted February 5, 2021 4 minutes ago, GabeShack said: Can I use a PIA from one of my spare Atari 400s or is it specific to the 800xl? They're all the same. In fact, Western Design Center makes a modern equivalent today that is apparently pin-compatible with the vintage 6510 chip Atari used. 1 1 Quote Link to comment Share on other sites More sharing options...
BillC Posted February 5, 2021 Share Posted February 5, 2021 2 hours ago, GabeShack said: Thanks for the suggestion. I’ll resolder them and try again. However it seems like all the points are showing continuity based on the schematic above but still worth a shot. Are you checking continuity from the pad, the pin, or the junction of both? A poor contact on the +5V and ground pins may also be unable to deliver enough power to the cartridge. There are also signals that the computer uses to recognize whether an 8k/16k cartridge is present. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 5, 2021 Share Posted February 5, 2021 after that U3, U2, and cpu... the assumption being ram tested as good. Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 5, 2021 Author Share Posted February 5, 2021 I resoldered the pins. Still no change. I swapped the PIA for the one from my 400. Still no change. Looking at U3, U2 and cpu next. 1 Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 5, 2021 Author Share Posted February 5, 2021 Well doesnt look like there is a spare U3, U2 for me to test from my 400. May have to get a spare 800xl from eBay, or just be happy with the 400 I already modded that works. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 5, 2021 Share Posted February 5, 2021 (edited) the one chip is common so try looking around or even ebay etc... might be a whole dollar give or take 74ls138 I think Edited February 5, 2021 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 5, 2021 Author Share Posted February 5, 2021 Thanks again. Just seems so weird that everything else works pretty normally. I reached out to Simius to see if there is any chance the Sophia 2 could be causing it, but since video is working I’d guess not. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 5, 2021 Share Posted February 5, 2021 You could have connected the RF to a tv to test it out first before modding the machine... Looks like you pulled a few things out... make sure no stray solder flakes or bridges exist and that no pads or traces became knicked/pulled 1 Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 5, 2021 Author Share Posted February 5, 2021 thanks again for the help. I did try it with a cartridge before I removed the rf with the same issue. I’ll definitely scan the board again for any loose solder or bridges although there isn’t much I actually changed aside from the GTIA and those joints all look clean. Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 6, 2021 Author Share Posted February 6, 2021 Simius is thinking its the MMU. I guess I can look for that chip individually or just get the U1MB. Thanks again all for the help with this. Really frustrating to just not know what the issue it. Quote Link to comment Share on other sites More sharing options...
GabeShack Posted February 8, 2021 Author Share Posted February 8, 2021 Testing the pins on the MMU with a cartridge in the slot shows 5v (4.9) on pins 6-9. So it looks like it is seeing the cartridge in the slot. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 8, 2021 Share Posted February 8, 2021 clean that cart port again, I blew up the image and there is stuff in the base of it, it can hold a cartridge up too high or even be shorting signals/interfering with contact. Do not weaken the port by spreading the swipes, jamming swabs in there often weakens the ports, only use card edge cleaner or diy equivalents that are the width of a standard carts pcb. hold the pcb upside down and blow it out if you have too... Quote Link to comment Share on other sites More sharing options...
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