24 Jul
2013
24 Jul
'13
2:07 p.m.
On 2013 Jul 24, at 3:58 AM, Rik Bos wrote:
If you
remove the memory subsystem RAM and register boards you
should have
space enough to measure the /Init signal.
But it is also available on the CPU control board, you have to
measure the
5V and /Init signal together and look if the /Init signal has
enough delay.
On the CPU control board you can find the /Init signals on U16 and
U17 both
74H108 JK-flip-flop's, the reset input is connected to the /Init
signal and
resets the Micro code PC at power on.
If you solder a small wire to it you should be able to connect an
LA or
Scope to it.
(As I mentioned earlier) the power-on signal is available on pin 3 of
the 6*2-pin test connector situated between boards 12 and 13. (+5 is
on pins 4/D and GND on 5/E). It is easily accessible to a test probe,
or one can cut a set of edge pins off a scrap plug-in board to make a
connector.