Quad 303 all versions illustrated upgrade guidelines V2.0
Page
5
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14
Step 2
– Installing the PSU & output capacitors
Remove the non-wired side of the printed circuit-boards from the plastic mounting-
clips using a small screwdriver.
In earlier versions of the 303, the PSU & output capacitors have been installed with
connections on the downside, in later versions the connections were on the upside of
the capacitors. In all versions produced, the connection of the capacitors to the cable-
beam is as described hereunder:
•
Green/Red wire on the left output-capacitor:
+ (positive)
•
Yellow/Red wire on the left output capacitor: - (negative)
•
Green/White wire on the right output-capacitor:
+ (positive)
•
Yellow/White wire on the right output-capacitor: - (negative)
•
Blue wires on the PSU-capacitor: - (negative)
•
Red wires on the PSU-capacitor:
+ (positive)
We will replace the original 2000
μF output-capacitors with 6800μF or 4700uF and the
2x 2000
μF PSU capacitors (in parallel) with 1x 4700MF 100V.
Modern capacitors are a lot smaller (and better) than their 6-ties ancestors. In some
cases you may need to wind some self-adhesive tape around the capacitor to fit it
into the mounting-rings (see the picture above). We will re-wire the PSU-connections
with new cable.
•
Solder Blue cable between the diode-bridge and the - (negative) of the PSU
capacitor.
•
Solder Red cable between the diode-bridge and the
+ (positive)
of the PSU
capacitor
•
Solder Yellow cable between the AC-connections of the diode-bridge and the
secondary windings of the transformer
The most practical way to solder several cables to the same point is to twist them
together before soldering.
The square LED with the 12K resistor can replace the old neon-bulb. The LED with
the resistor in series should be connected to the
+ (positive)
and - (negative) DC
voltage of the PSU. Watch the polarity of the LED, the long lead should be connected
to the
+ (positive)
and the short lead to the resistor. The other lead of the resistor
should be connected to the - (negative) of the PSU.
DaDa Electronics
