[sdiy] Funky flip-flops

[Karl Ekdahl]

Hi all, i've got a strange problem. I have 8
flip-flops (4 * 7474) which all share a common ~SET
line and each have it's ~RESET tied to ground trough a
10k resistor. Each flip-flop is connected to itself
via ~Q -> D and each is set/reset trough a push button
connected to CP. All Qs are connected to one LED each.
So, pushing the first button sets/resets the first
flip-flop. Pushing the 8th button while the first
flip-flop is set resets the FIRST one and sets the 8th
one. Pushing the 8th resets the 8th flip-flop and then
pressing the 1st sets BOTH flip-flops. All the
flip-flops reacts like this with eachother in all
kinds of strange patterns. The only way they possibly
COULD interact with eachother should as i understand
it be 

a) the comon SET
b) trough the RESET resistors to ground (?)
c) trough the 74245 that delivers the signals from the
pushbuttons.
d) powersupply noise (?)

a) could probably be ruled out since they bot SET and
RESET eachother. b) and d) is the same i guess and i
have a pretty huge powersupply feeding only a couple
of TTL chips, so that seems unlikley. I had
powersupply problems earlier but fixed that. c) the
74245 seems to give perfect result while looking at it
with my multimeter, so i don't think so...

I'm stranded, anyone?

btw. i might as well thank everyone for their help
with various things the last couple of weeks, i'll put
some pictures and stuff of what i'm doing somewhere in
some time..

Karl