TestingTheColorComputer

Testing the Color Computer

There are a few ways to test operation of a Color Computer. This may be useful when buying or selling a CoCo, when taking out old equipment from storage or simply to test your daily driver.

These tips for testing apply to all Color Computer models unless otherwise noted.

Preparing to test

• Discharge yourself of static electricity.
• Make sure no objects have fallen into the CoCo through the ventilation slots or Program Pak slot, possibly causing a short circuit
• Consider using an Uninterruptible power supply (UPS) to ensure having a continuous, noise-free power source and avoid damage to your equipment.

Quick power, keyboard and CPU test

The CoCo controls a tape player connoected to it through the CASSETTE port, via an internal relay that makes a distinctive "click" sound. There is no need for any cable or tape player for this test.

To test your Color Computer power, keyboard and CPU without any extra tools :

• Connect your computer to a power source, make sure it's the proper voltage
• Power on the CoCo, a "click" sound should be heard from the relay controlling power to the cassette port. The same click can be heard when the CoCo is powered on and you press the RESET button.
  • If you heard the relay sound when powering on, compare it to pressing the RESET button several times. The RESET button sound should be different when the CoCo is ON or OFF.
  • After hearing the relay sound and turning on the CoCo, type MOTOR ON (follower by the ENTER key) blindly. You should hear again the relay sound

If you've heard the relay sound after typing MOTOR ON, there is a good chance the power, CPU and keyboard are functional on your CoCo.

Display test

All CoCos come with a standard RF output port (RCA female connector). This can be confusing as many older computers and game consoles with such a port can be connected to a standard composite monitor.

The CoCo can't use such a monitor directly, as it was originally designed to be connected to TVs commonly available at home.

In order to test video operation you need to connect the CoCo to a modern TV, using a coaxial connection. The easiest and cheapest way to do this with common components is to get a cable and adapter as follows :

• F-Pin Female to RCA Male Adapter
• Coaxial cable

1. Connect the adapter to your CoCo and to the cable. Connect the other end of the cable to the TV.
2. Turn on the TV and change to channel 3 or 4
3. Turn on the CoCo, play with the switch behind your CoCo. Only one setting may work best on your TV depending on different factors.

Troubleshooting

• One common cause for a CoCo to be "dead" is the chips becoming loose over time and moving. Make sure the CoCo is off and disconnected, then open its case and reseat any chips.
• Some capacitors may have blown or leaked over time. These components can be replaced by yourself if you have the soldering experience, some people in the community also offer this service.