The receiver IC, an SL660C, can be found on the left side of the circuit board. To reach the IC, the outside and inside covers have to be removed. The unfiltered audio can be found on pin 8 of the SL660.

Follow the next steps to make the discriminator output:

• Connect a 10 k resistor, a 2.2 nF ceramic capacitor and a 10 uF electrolytic capacitor as shown on the picture. The plus pole of the 10 uF capacitor is connected to the resistor and the 2.2 nF capacitor.
• Connect the core of a piece of shielded wire to the minus pole of the electrolytic capacitor
• Connect the shield of this wire to ground, together with the free lead of the 2.2 nF capacitor. The two 47 pF capacitors next to the SL660 are a suitable ground point.
• Connect the other side of the shielded wire with a 3.5 mm mono chassis socket

The chassis socket can be mounted in the cover plate of the unused right input. Use some hot glue to fix the cover plate.

Photos and text: Henk van Rooijen