33
5) BBD Clock Adjustment
Set Effects Mode to Ensemble, Intensity to 10 and other settings to Normal.
a) Check TP1 with Oscilloscope and adjust VR1 to obtain a maximum clock cycle of 30uS.
b) Check TP2 with Oscilloscope and adjust VR2 to obtain a maximum clock cycle of 30uS.
c) Check TP3 with Oscilloscope and adjust VR3 to obtain a maximum clock cycle of 30uS.
6) PolySix Common Faults
Unable to tune correctly
If you find you cannot tune the Polysix and the scale is well away from correct and cannot be adjusted using the trims then your synth may well have a fault in the
master tuning area. One common fault is the optocoupler labeled PC-1. These are no longer available but one replacement that works is a Vactec VTL5C9 which can
be found at Small Bear Electronics (
www.smallbearelec.com
) or EBay at the time this manual was written.
To check that it is optocoupler PC-1, using a DVM with test point 5 for ground, measure IC18 pin 7. It should be somewhat between -2v and -6v. If it measures -13v
the optocoupler is faulty and should be replaced.
Another less common failure that effects overall tuning is Q12 (which is under a rubber hat). This is a 2SC1583 matched transistor pair and can be found at Wagner
Electronic Services (
www.wagner.net.au
). For tuning and scale problems it is also a good idea to change the TL071 (IC17, early version only) and the TL072 and
4558 op amps (ICs 17, 18 & 19). These are commonly available and cheap.
The SSM2044 filter chip and SSM2056 Env generator chips can be found on EBay. The SSM2056 is beginning to get harder to find and more expensive.
Bad key contacts.
Almost every Polysix that has come through the Kiwitechnics workshop over the years has had problems with key contacts. Two things cause this, one is the gold
plating on the contact board developing an oxidizing type coating over time (yes gold shouldn't oxidize so it isn't pure) and the other is the carbon used in the rubber
section is not very conductive. New replacement rubber contact are being made by LA Synth at time of printing. The URL is http://shop.lasynthco.com/product/key-
contacts-for-korg-poly-oberheim-sequential-prophet-600-kawai-and-others
www.kiwitechnics.com
KiwiSix Upgrade User Manual v3
