Hi Coleman,

The function of Q1 is very simple, it converts the low-level (5V)
gate signal coming of the main processor and converts it to a 12V one
to send out on the bus. It is hard to imagine anything being 'wrong'
with this, *unless* for some reason there is already 12V on the gate
line on the bus - if the 190 then commands a 'gate', Q1 will have 12V
across it with NO current limiting, which probably implies melted
transistor and blown fuse (which sounds pretty much like what
happened). Thus you need to establish whether there *is* any voltage
on the gate line when the 190 is disconnected - I suggest double-
checking that all other modules are connected to the bus properly,
red stripe on ribbon 'down' at both bus and module ends, and none
displaced by a pair of pins upwards or downwards.

I expect that the AD5 is on correctly, but check anyway (red stripe
down, 'up' arrow pointing upwards, and also not displaced by any
number of pins). All the 'programming' LEDs are driven by the 5V
supply, and you say these light OK - unless of course there is some
other voltage, like 12V, on the 5V bus..).

If you have a meter that will help (but take care poking around with
the mains on....).

Whether there is any more damage to the 190 other than the blown
transistor is hard to say - once you've isolated the problem,
replacing the transistor and trying again is probably the easiest way
to find out!

Tim


--- In Doepfer_a100@yahoogroups.com , "Mickey Finn" <hornography@y...>
wrote:

> So I had just recently posted that I was having trouble with my

190. I had received it a

> month ago but finally got around to plugging a midi cable into it..

I could not get any

> gate/clock leds to light. It would select options (config/perform)

with the correct led

> sequence, and even list the version number; but there was something
> wrong.. I opened her up and re checked the cables. I powered up and

blew a fuse. I then

> replaced the fuse and powered up again and smoke started pouring

from the 190.. I

> powered down and opened up the 190 and the Q1 transistor (bc549)

had pretty much

> melted.. the rest of the system is fine, I just checked; so the

power supply is okay.. Maybe

> this was a faulty 190 I'll return it, or should I try replacing

the Q1 transistor Anybody

> else have this problem
>
>
> Coleman.