exxos's Atari, Amiga & retro forum

The Falcon is now on the bench!

I picked up the stuff from work thins morning and the first thing to test was to see if either or any of the two 72 pin 16MB SIMMs would work in the machine.

Well, the first one didn't. Just a dark screen with some coloured lines down the right hand side of the screen with the diag cartridge plugged in.

The second one needed some of the contacts cleaning with a fibre pen before inserting but once that was done... all good. I'm now running YAART-TT on the machine and it's on pass 2 now. I'll leave it running until after lunch, after which I'll start dismantling the machine more ready for its NVRAM-ectomy.

With the old NVRAM safely removed I fitted the Exxos replacement. However, instead of installing the small coin cell on top (which I don't have) I soldered wires and a CR2032 holder, which I can install in a location where it can be easily changed without dismantling the whole system. Hot glue to the rescue!


Seeing as there are currently no (CPU) clock issues I'll leave the clock patch for another time I think. I realise that if/when chips' tolerances drift over time I may have to go back and revisit this as the timings are on the edge.

Could you scope the clocks on both sides of the resistors where the clock patch wires normally go ? On x10 of course.

I'm actually writing a article about the clock patch stuff.. But don't have a stock machine anymore..

OK, I'll see what I can do later, when the Sun goes down and I can take pictures of the 'scope screen.

Well, that's fascinating. The mounting holes for the original 2.5" hard drive don't correspond with later, standard holes. I've had to use double-sided foam tape to stick the new drive into the machine.

exxos wrote: 07 Aug 2022 15:35 Could you scope the clocks on both sides of the resistors where the clock patch wires normally go ? On x10 of course.

I'm actually writing a article about the clock patch stuff.. But don't have a stock machine anymore..

Just to be clear. This is two probes, one each side of each resistor in turn? How about one probe per clock line to determine skew?

Just checked with one probe. They all look nice. 5.12V on one side and 5.04V on the other. All nice and clean and almost a perfect sine wave.

stephen_usher wrote: 07 Aug 2022 17:07 Just to be clear. This is two probes, one each side of each resistor in turn? How about one probe per clock line to determine skew?

Just checked with one probe. They all look nice. 5.12V on one side and 5.04V on the other. All nice and clean and almost a perfect sine wave.

One side of the resistors is all connected together. The other sides are clock outs. You measure each point to gnd.

Are you testing with x10 probe ?

Please forgive the pictures. Holding the phone in one hand whilst probing with the other.

R216


R221


R222

Thanks.. That's confusing now.. As if the clocks are that clean, there would be no need for a clock patch. I've seen all sorts of ringing..always. I'll have to refit the resistors on mine and see if I get the same results.

I've always heard rumours of Falcons that don't need clock patches, @stephen_usher please upload high Res motherboard photos at some point :)