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if NOT CV control ,
connect a potentiometer to the MicroK and check the range
from zero to full effect
= effect starts , now disconnect pot
and get value with multimeter
Joined: 01 Apr 2011 Posts: 340 Location: 3rd Stone from the Sun , Bavaria
Posted: Sat Jun 08, 2013 6:43 am Post subject:
first : I am not responsible for any damage to your "Dinosaur"
(there IS danger of damaging it )
do you know of a pedal that did work in the past ?
how many cables are connected to the DIN inside MaxiK , 2 or 3 ?
do you have a repair manual ?
now I understand this :
20 Volts (!) out from the DIN jack ( so vintage )
attenuated by FC7
and back into the same DIN
so in theory you would want to connect the FC 7 in serial at first
(or as a voltage divider with 3 cables at the DIN inside the MK)
at least 1 thing to consider:
there might be a limitation of current inside the MaxiKorg
then maybe (!) you may go as low as zero Ohm , *DANGER* )
if not :
when the FC7 is at a position that gives you lets say 10 Ohm
you would have a current of
20 volts/10 Ohm = 2 Ampere
that gives you 20 volt x 2 A ---> 40 Watt !!
(thats more than enough to fry something )
2 millimeters further it is 100 Ohm:
20/100 x 20 = 4 Watt
I am not shure if the FC7 can eat that ...
+if your synth would like this (close to shortcut) situation *DANGER*
so probably an extra resistor for safety in series is necessary
depending on the combined resistance (pre-resistor + pot )
= a resistor with an appropriate high Watt value
first steps :
to check the pinout of the DIN jack :
how many wires connected inside MK ? (wants to be opened)
1."quick n easy check"
cut off one plug of a MIDI cable
evtl the standard MIDI cable is too thin for high Ampere values ?
I am not really shure
(you could use it to connect to FC7 cable , - later if possible at all)
2.better solder solid cables to a single MIDI jack
access wires
check out the Voltage pins with multimeter (or your tongue , NOT )
experiment with a potentiometer to find the the values of
the working range and use a pot with high enough power rating
(start 1 Meg Ohm ? )
use a second pot as a safety resistor
start with high ohmic values (1000 Ohm ---> 0.4 Watt)
be very cautious with low ohmic values
if you are not shure what you are doing , leave it ...
and consult a vintage specialist or an electronic guy (recommended)
post for more questions , or post your result , I am interested ..
btw: just checking your website ....
dont You know a good tech ? could be an easy solution for him
Last edited by WaterDrum on Sat Jun 08, 2013 1:23 pm; edited 1 time in total
Joined: 29 Dec 2002 Posts: 200 Location: Portland, Maine USA
Posted: Sat Jun 08, 2013 1:06 pm Post subject:
Thanks for your help.
I do know a tech....though his hourly rate is higher than mine, I guess in this case it would be worth it. I could easily solder the jack, but I need someone to evaluate the resistance and not fry the synth.
Also, I read that the filter input does take 20volts, but I am not sure I trust that. The other thing which complictes this is that the Maxi has two din pedal inputs and I want one pedal to go to both.
I will take it my tech. _________________ Korg Gear: (2) Kronos, PS3100, (2) MaxiKorg, PE1000, Z1Ex, MS20M,(2) OASYS-PCI, Synthe Pedal, Wavedrum WD-1, Prophecy, SQ1, 2600FS, M3M
Joined: 01 Apr 2011 Posts: 340 Location: 3rd Stone from the Sun , Bavaria
Posted: Sat Jun 08, 2013 1:29 pm Post subject:
just edited a little bit
so we meet here ...
there is a stereo pot with the same values 2 x 50 KiloOhm avaiable as a sparepart for FC 9 (from Yamaha)....
could solve your prob ...
maybe show my post to the tech , he will know what to do
Quote:
Also, I read that the filter input does take 20volts
Joined: 01 Apr 2011 Posts: 340 Location: 3rd Stone from the Sun , Bavaria
Posted: Sat Jun 08, 2013 2:24 pm Post subject:
thats odd ...
you could experiment with pots in the way I pointed
for the 20 volt and for the 9 Volt
but from now on you might better have a service manual .
and/or a plan of the circuit
Joined: 29 Dec 2002 Posts: 200 Location: Portland, Maine USA
Posted: Sat Jun 08, 2013 2:41 pm Post subject:
I think I am going to wire a cable and try a low external voltage from a Moog cp251 of 5 volts and see how much that affects the filter. If it's enough for my needs, I could use one pedal into the cp251 and feed voltage to both filter inputs quite easily. _________________ Korg Gear: (2) Kronos, PS3100, (2) MaxiKorg, PE1000, Z1Ex, MS20M,(2) OASYS-PCI, Synthe Pedal, Wavedrum WD-1, Prophecy, SQ1, 2600FS, M3M
Joined: 01 Apr 2011 Posts: 340 Location: 3rd Stone from the Sun , Bavaria
Posted: Sat Jun 08, 2013 3:25 pm Post subject:
so you want to send voltage ontop of an existing voltage ...
not shure if that works .
Main question :
is this a CV signal input (e.g.for a stepsequencer) ???
or kind of an "ohmic insert" ?
you shure have a dedicated knob for the filter function ?
trace the cables that are soldered to the knob (=potentiometer)
is there some kind of connection to the DIN ?
can you read the value of the knob potentiometer ?
the two "9 volt pins" are they connected (=identical)?
9 volts against ground ?
Joined: 29 Dec 2002 Posts: 200 Location: Portland, Maine USA
Posted: Sat Jun 08, 2013 4:44 pm Post subject:
Yes, an original Wavedrum with the programmer.
I have the schematic for the DV800...though, that model doesn't have the Din filter pedal connections. I think only the Univox branded Maxi-Korgs in North America had them...but perhaps in other places too?
Joined: 29 Dec 2002 Posts: 200 Location: Portland, Maine USA
Posted: Sat Jun 08, 2013 4:59 pm Post subject:
I believe the filters are CV controlled from pin 5 on the DIN plug.
I am going to try 5 volts and see how limited the range is...if I need more voltage, I will probably have my tech create a proper connector for it. _________________ Korg Gear: (2) Kronos, PS3100, (2) MaxiKorg, PE1000, Z1Ex, MS20M,(2) OASYS-PCI, Synthe Pedal, Wavedrum WD-1, Prophecy, SQ1, 2600FS, M3M
upper din pin 5 connects 1 resistor to both integrated circuits
might be inputs
2nd din has a ground connection to a kind of "jack matrix"
labeled as "accessories" (= insert effects" ??? )
2nd din has no more pins connected (?)
pin 5 points to "for lower" ??
2 possibilities now
1. the IC is waiting for CV , you put voltage in and all is good
2.the IC wants to have an easier connection to ground ,
what you wanna do is not to lower the voltage ,you want to raise it .
this could be fatal
-if you burn a resistor ,well , ok ...
-if you burn an integrated circuit chip (hard to get ....)
you need to understand the circuit , or be *Extremely* cautious
you will know
still curious .
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page 3/11 you find the DINs ...
