vanishing point 2.1 debug once again

[fifi]

another thread about this, didn't wanted to hook in on another one's thread so i opened this one.
so ive tried out this cool project (BIG THANKS andrew!!), the normal step sequencer works fine.
but with the random mode there's something odd, it does something like a pattern:
1-2-3-4-5-6-7-8
X---X---X---X--
this will be repeated a couple of times the it jumps to a pattern like this for like 1-2 cycles and back to the first:
1-2-3-4-5-6-7-8
--X---X---X---X

x indicates LED lights up, so i get something similar like this: 1 3 5 7 1 3 5 7 1 3 5 7 2 4 6 8 1 3 5 7 1 3 5 7
i can vary on which of the both "patterns" it stays longer by truning the speed pot.
so its kinda random but also not it just jumps over one step and the random seems to be between the 2 patterns it runs.

i did this on my own pcb which is based on michael allens layout, just moved the powersupply offboard, also added some space because my caps wont fit on his board.
ive attached the layout.
heres a little legend for the colored solder points.
brown = steps
blue = reset's (i used the diode trick to have maximum 8 steps and choice between 4/6/8 steps)
green = speed pot
red = power (+9v)
orange = step/random switch
grey = limit pot for the led of the optocoupler, and the black pad next to it is were the optocoupler - connects


now as andrew the tonegod mentioned in another post, ive did following stuff to make sure random clock works:

Ok so sequence mode works fine. I'm wondering if the inhibit pin is being driven correctly. Could you hook in the random clock to the clock pin by disconnecting the sequencer clock from pin 14, moving pin 13 to pin 14, then grounding pin 13 ?

so when i do this, the random clock drives my cd4017 i can controll speed via speed pot, but there's something strange there, it always skips step1 !
i get this result. 2 3 4 5 6 7 8 2 3 4 5 6 7 8 

any ideas why this is ? dont think it should be happen.
(i may be happy when i increase the 1M/100nF combo to have longer random cycle like it would jump over 2 steps instead of only one. but that 1st step skip is stopped me from going further on mods on the pcb)

thanks in advance

[The Tone God]

That is a head scratcher. Are you using the reset / stage selector ?

Andrew

[fifi]

hi andrew,
thanks for hooking in on this.
wondering where my layout  is gone ?!?! ive reattach it again


so, yes i use the stage mod, just tested it now, the stage select works fine 4/6 steps.
just found one intersting thing, if i disconnect pin 9 (step9. which would limit me to have only 8 stages) which i ran over a diode to the reset pin,
stage 1 gets selected! well there is a lil gap between stage 8 and 1 but the timing is exact as it performs stages 9/10 too so that way it runs ok, if i connect pin9 back to reset again stage1 dont get selected. to say when i drive the 4017 with normal clock it runs ok 12345678 cycles, the 1st stage problem only occurs when i drive the 4017clock with the random clock.
maybe thats a hint where the dog could be burried

[fifi]

hmpf, again the layouts gone, woot? or is my browser cache "plemplem"
so heres the link: http://img512.imageshack.us/my.php?image=vanishingpoint21layoutae3.gif

ok i did some more check of my cabling, because i had to pull ic out of socket put it into breadboard and wire it back to the socket, so there might have been an error, but it was ok, ive found out that i had R1 to 100K when i was probing around getting random mode working right (on your schematic its 10-100K) i switched it back to 10K, now the sequencer steps ok with the random clock as it should!
1234567812345678...

so the random clock should run fine.
also did set up it in normal but random is still just jumping over 1stage as i said in my first post

[The Tone God]

Give me a day or so. I'll go through your layout. If it is ok I am going to rebuild VP2.1 on another board to check things.

Andrew

[fifi]

sound good, i really appreciate that you are sacrifice your time for me!
thanks