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Timbucus · 31st May 2020, 10:44 am

I have just put the VDU board on the Scope (I really was too tired last night and had to tidy up the desk for half hour to see the screen!)

I did remember my XOUT patch - unusually for me I reread the thread we discussed it all in as it was that that reminded me to bend up b15 as well to take over to b8 when I am ready.

My machine is a bit slow today as I am running a 1TB backup over USB2 to an external drive...

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The bent out b27 makes a handy earth clip point as well!

So the clock is nice and strong 4V in and can be seem as nice clean square waves on Pin 3 of IC4 (no output on pin 5 of that latch so the feed from IC6 via the four gate NAND on IC13 and NOT on IC12 are doing nothing).

It is also an even cleaner square on Pin 14 of IC3 from the IC4 Flip Flop.

Just on the off chance the scope on the Composite (rather than the TV) shows a nice 1.5V p2p normally high with 10ms low pulses every 80ms so some counters are running.

31st May 2020, 10:44 am	#467
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,363	Re: MK14 schematic revisions I have just put the VDU board on the Scope (I really was too tired last night and had to tidy up the desk for half hour to see the screen!) I did remember my XOUT patch - unusually for me I reread the thread we discussed it all in as it was that that reminded me to bend up b15 as well to take over to b8 when I am ready. My machine is a bit slow today as I am running a 1TB backup over USB2 to an external drive... The bent out b27 makes a handy earth clip point as well! So the clock is nice and strong 4V in and can be seem as nice clean square waves on Pin 3 of IC4 (no output on pin 5 of that latch so the feed from IC6 via the four gate NAND on IC13 and NOT on IC12 are doing nothing). It is also an even cleaner square on Pin 14 of IC3 from the IC4 Flip Flop. Just on the off chance the scope on the Composite (rather than the TV) shows a nice 1.5V p2p normally high with 10ms low pulses every 80ms so some counters are running.