Jerrold 400 DRX-3a Full Service Modification
by 4x of Group 42
Introduction
This information is good for the Jerrold 400 DRX-3A Addressable units.
Instructions
- Remove existing PROM, if any.
- Short wire-wrap posts 1 and 2 togeather.
(see digram)
- Cut out transistors on decoder board.
(see digram)
- Install a 100K resistor between pins 6 and 7 of IC U2.
- Install a 1.8K (1.5k or 2.0K will work in a pinch) between pin 6
of U2 to pin 6 of U4.
- Install a 10ufd, 25 volt cap between pin 6 of U2 to pin 14 of U3
(+GND U3-14).
AM/FM data receiver
In some cases this additional mod is needed.
- Install a NPN transistor and a 27K resistor between transistor
9 and 10 as shown.
