Analogue-sequencer

Changed the sync cable, started from scratch again & she's syncing
lovely now.

Ive been too long without one of these beauties :)

Thx for your help Colin.

/m


--- In analogue-sequencer@yahoogroups.com, "Colin f" <colin@c...> 
> 
> My 808 usually runs in perfect sync with the P3, although sometimes
it does
> miss a single clock pulse as it starts, which I've not yet looked
into to

> determine the cause.

> Cheers,
> Colin f

> Just got an 808 after putting it off for a long time :)

I picked one up myself a few months ago, and got a 909 to go with it in the
last few weeks.
:-)
Both the 808 and 909 are slaved to the DIN sync output on my P3.
 
> However the sync with the P3 is all over the gaff.
> Im hoping this is just due to my inepititude with programming 
> the 808 but
> ive tried many things at this stage and its not syncing 
> properly. Its seems
> to be running at 4/3 time or something. Its wierd cause the 
> 606 syncs up
> perfectly with the P3.

My 808 usually runs in perfect sync with the P3, although sometimes it does
miss a single clock pulse as it starts, which I've not yet looked into to
determine the cause.
The first thing to do is to make sure you have the pre-scale on the 808
pattern set correctly. Set the scale switch to the 4/4 position (3rd down)
and press the pre-scale red button while running in pattern write.

If the 808 is just missing a lot of sync pulses (i.e. it falls behind
gradually rather than running at an accurate but wrong division of the
tempo) it could either be a dodgy sync selector switch or socket (crackly
connections), or the internal adjustment of the interrupt timer could be
wrong.
The 303, 606 and 808 all use similar processors (an NEC 4-bit
microcontroller). There is a clock circuit that generates a pulse every 2ms
which drives the interrupt pin on the processor. The interrupt routine that
is triggered as a result is responsible for various things, including
reading the sync input pins on the CPU to see if a clock pulse is active.
The problem with this is that if the adjustment of the interrupt period is
out, the CPU can miss sync pulses, and ends up falling behind.
To set this up accurately, you really need a scope, although you could do it
with a tuner by connecting the clock output up as an audio signal (2ms
period = 500Hz). 

Cheers,
Colin f

Just got an 808 after putting it off for a long time :)

However the sync with the P3 is all over the gaff.
Im hoping this is just due to my inepititude with programming the 808 but
ive tried many things at this stage and its not syncing properly. Its seems
to be running at 4/3 time or something. Its wierd cause the 606 syncs up
perfectly with the P3.

Anyone driving an 808 from the P3? A step-by-step would be appreciated or
have i bought a dud?

Thx

/m