damanloox Posted June 5, 2021 Share Posted June 5, 2021 I desperately need help with my 130XE that I took out of the drawer (with the intention of upgrading). Long story short - it doesn't work... One of the two screens attached ("empty" blue screen) is what it does on s-video. The other one is with SysCheck inserted (it sort-of starts but it's not what I'd expect to see)... Any ideas...? I replaced OS ROM, Antic and MMU - same result every time... Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted June 5, 2021 Share Posted June 5, 2021 Any difference if you set the sys-check to supply the base 64K? Also thinking maybe worthwhile to try swapping the 74LS08 buffer with a 74HC08 or 74F08 Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted June 5, 2021 Share Posted June 5, 2021 If it has ram marked “MT” - replace. That micron technology ram has the propensity to not reset after powering down. Quote Link to comment Share on other sites More sharing options...
damanloox Posted June 5, 2021 Author Share Posted June 5, 2021 @Nezgar SysCheck provides 64k of ram and disables onboard Ram by default (IE dip3 set to on on off). @Paul Westphal no MT memory on board. Wouldn't SysCheck work if memory was bad? I mean it sort-of works but the screen is not what it should be. Btw - when booting in composite the screen is red and not blue... 1 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted June 5, 2021 Share Posted June 5, 2021 OK, instead of sys-check dip3 on-on-off, any difference with off-on-off? We see a GTIA 80 hozizontal pixel mode (ie Gr.9) being engaged here - so its possible GTIA is suspect, but im not sure how that could hang the system. Maybe clock buffer (74LS08) since MMU, ANTIC, OS ROM has already been ruled out... maybe CPU. 1 Quote Link to comment Share on other sites More sharing options...
Sugarland Posted June 6, 2021 Share Posted June 6, 2021 One of the causes of a power-on blue screen hang that way is a bad POKEY. The machine is trying to poll SIO for devices (to boot a disk, etc). Your photo isn't too clear. Is there video corruption or is that a stock-standard blue screen cursor? If the latter, try replacing pokey. Quote Link to comment Share on other sites More sharing options...
damanloox Posted June 6, 2021 Author Share Posted June 6, 2021 Yes, video is corrupted (which is clearly seen with SysCheck - it's not a bad photo, it's exactly what is on the screen) Quote Link to comment Share on other sites More sharing options...
damanloox Posted June 6, 2021 Author Share Posted June 6, 2021 And there's no difference when I set SysCheck dip3 to off/on/off... Quote Link to comment Share on other sites More sharing options...
damanloox Posted June 6, 2021 Author Share Posted June 6, 2021 OK, problem solved. That purple patch cable got detached from 74LS08 (red circle on the picture). I soldered it back and everything is working perfectly now. Anyway - the board is now recapped, socketed (where I plan to put upgrades ie. U1MB, VBXE and PokeyMax) and I think I'll put sockets under all RAM chips (because what else would I be doing on Sunday morning BTW - those spots of flux here and there will be cleaned (just wanted to mention before the purists start screaming at me ) Thanks for all help. 3 Quote Link to comment Share on other sites More sharing options...
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