exxos's Atari, Amiga & retro forum

Just wire over it, or replace with a low value resistor like 22R,33R,47R values.

exxos wrote: 10 Nov 2023 18:13 Just wire over it, or replace with a low value resistor like 22R,33R,47R values.

Thanks. I wired over it and I get video, but just black. No Atari logo, etc. The signal is 15.7Khz H, and 50.1Hz V, 712x242, which seems correct. So, progress. I'm going to probe the bus to see what's happening there.

Sounds like progress to me :dualthumbup:

Any progress is good progress :dualthumbup:

Indeed! Something's happening. :-)

Good ! Carry on that way.

Yes, very happy about the progress. Thanks to everyone for the advice and help!

That's definitely good news. You've got basically basic RGB output from Videl. The most common state with black screens is getting "out of sync" on monitor and bye. Perhaps ROM and/or RAM is not getting its chance to do something further. You could try the diagnostic cartridge + serial output next, that would certainly narrow it down (no change -> even first bytes of ROM are unavailable).

mikro wrote: 13 Nov 2023 07:13 That's definitely good news. You've got basically basic RGB output from Videl. The most common state with black screens is getting "out of sync" on monitor and bye. Perhaps ROM and/or RAM is not getting its chance to do something further. You could try the diagnostic cartridge + serial output next, that would certainly narrow it down (no change -> even first bytes of ROM are unavailable).

Thanks @mikro. I'm going to try to get a serial cable connected and see if anything is output there. I tried a diag cart (all-in-one set for 030 mode) and nothing changed. I did probe all CPU address lines and also the expansion connector address lines and all similar lines agreed. They are all stuck at a consistent value. [23:0] 01101000100101101111111 (0x344B7F). Not sure if that's relevant.

I've also ordered some replacement components to reverse the partially removed phantom mod, which I suspect is part of the remaining issue. I think R233 and R39, which are currently missing, might be needed for things to work normally, so I'm hoping replacing those gets me a little further. They both seem to be associated with clock signals (R233 - ECLK, R39 - PCLK4).

Well, without a clock nothing will happen, guaranteed.