exxos's Atari, Amiga & retro forum

Hopefully tomorrow.

stephen_usher wrote: 01 Feb 2024 13:22 Hopefully tomorrow.

:crossed1:

Taking some more measurements I can't help but think that the voltages are just too low in the clock circuit. I've measured some peak to peak voltages of between 1v and 2.5 volts, with the majority at just 1.5v.

Specifically pin 5 is 1.5v peak to peak, so perhaps not enough to drive the gate that outputs at pin 6. It definitely isn't the IC that's for sure, as I fitted new and the results are the same.

Hope the 8Mhz xtal comes soon...

But the input to pin 5 is coming from the 74LS00! Try a 10K pull-up on that line?

stephen_usher wrote: 01 Feb 2024 15:24 But the input to pin 5 is coming from the 74LS00! Try a 10K pull-up on that line?

Indeed it is and that's low too. Will see if I ave any 10K resistors handy, pretty sure I do, see if it helps, good idea.

Did you get a chance to test this?

stephen_usher wrote: 01 Feb 2024 21:58 Did you get a chance to test this?

Unfortunately not. I'll hopefully do so in the next day or so.

Fair enough. :-)

stephen_usher wrote: 01 Feb 2024 21:58 Did you get a chance to test this?

Tested this morning, made no difference.

Oh well. Shows that it wasn't the voltage level then.