Serial Loopback Adapter

Serial Loopback Adapter

A serial loopback adapter is required when perform a serial loopback test in Amiga Test Kit.

Requirements

• Female DB25 plug and (optionally) a case/hood.

• Wires to join pins together.

• Optional: LEDs and limiting resistors.

Build Instructions

Use the wires join the following pins together:

• 2 and 3

• 4, 5 and 6

• 8, 20 and 22

Optional:

• For +12V, connected the negative side of the LED to pin 7 (GND), the positive side to a 1K resistor, and the other side of the resistor to pin 9 (+12V)

• For -12V, connect the positive side of the LED to to pin 7 (GND), the positive side to a 1K resistor, and the other side of the resistor to pin 10 (-12V)

Below is a diagram to summarise how the pins and components are connected together:

Amiga Test Kit

When performing the serial loop back test, all the connected pins should GREEN.

A failed serial loop back test would have some RED on the pins:

Typically, a failed serial loopback test means that one or more of the serial chips (U38 and U39 on an A500/plus) has failed and needs to be replaced.