Well, congrats. I worked with one at one time and found the 50Ohms-only inputs annoying. But if you don't bother exchanging the scope on your desk when you want to do general-purpose, 1MOhms measurements, you got now as much speed as this series can provide.
Yeah, I'll keep my TDS784D, it has TV trigger too which the TDS794D doesn't support.
One for general use, and then this hotrod for special use.
It needs some love though, it has a "ERROR: diagnostic test failure, dsyRastModeV0Walk, raster fail @ 1,1 read: 8, expect: f" error to track down, and channel 2 is showing spurious spikes, might be a RAM issue. Luckily I have spare parts from other boards....
Alrighty, I swapped the processor board in from a spare 754D that is identical to the 794D (The 754D has a busted acquisition board, I need to get my hands on an unobtanium chip, or a new acq. board) and loaded the 794D v8.0e firmware that I pulled from the original 784D processor board.
Booted right up with no "dsyRastModeV0Walk, raster fail" error, so that means it's probably a video RAM or other video problem as I thought which is good, narrows it down away from the 794D specific (I.e. I have no spares) acquisition board.
I think I'll keep the busted board with the busted scope and fix it there. I have enough spare parts to get it done when I get to it.
I might try the v8.0e firmware on some of my other D-series scopes. I wonder if it's 794D specific or will be an upgrade to the V7.x I'm using now on the 784D and 754D's... If it is incompatible it doesn't brick the scope, you just need to erase the NVRAM then flash it back to the previous firmware and you are back up and running.
Next step, figure out what's up with the channel 2 malarkey. It looks almost a bit like a RAM interleaving issue (image below), hopefully. I have spare RAM chips, so I can swap them out one by one until it works, all going well.......