Posister???

Sean Costello costello at seanet.com
Sat Jul 11 04:28:08 CEST 1998


Tom Moravansky wrote:
> 
> Has anyone ever heard of a posister?  The Roland JP-8 seems to
> use them to help control oscillator pitch.  I need one.  The
> part number in the service manual is  TSP 102J  (1K).  I checked
> on-line and in the Newark/Farnell catalog and no luck so far.
> 
> If I can't fix this oscillator, I'm going to part out the JP-8, so
> if anyone wants/needs replacement parts, let me know and it might
> help make the decision easier.

I know that there is a part called a "posistor" in the TB-303 (I'm not
really a big 303 nut, but I have had a huge schematic of the thing
hanging behind my computer at work for decoration for the past few
years).  It is in the same place as a tempco resistor would be.  My
guess is that it is some sort of temperature compensating resistor (a
resistor in which the resistance varies with temperature, used to
compensate for the temperature sensistivity of semiconductor junctions),
although it may not have the same type of temperature behavior as the
tempcos found in ARPs, Moogs et al.  

I have posted this to the bright kids on synth-DIY, so hopefully a real
answer will be coming soon.

Anyway, don't sell the Jupiter-8.  I know that there are companies that
still make temperature compensating resistors out there.

Sean Costello



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