Commodore 64 Troubleshooting

Your device will not power on as it is supposed to.

The Commodore 64 original power adapter is known for going bad and frying the CPU or RAM . It is recommended to use a modern adapter.

Power adapter may not be plugged in all the way, or the power adapter socket may be loose. Check to make sure the power adapter is plugged all the way in the socket and that there is no movement from the power socket.

Due to the age of these machines the contact between chip legs and their sockets can lose contact. Remove and re-seat socketed chips.

A computer memory problem can prevent boot up. Check for hot RAM chips and proper voltages.

This chip handles sound, if it is preventing booting removing it will allow the system to start.

Check the bottom of the motherboard for cracked joints.

Try booting a good, clean game cartridge to bypass the Kernel ROM.

Unfortunately any dead chip on the C64 can prevent it from working. Try to remove chips one by one until you see different behavior.

There is some issue with your computer screen (visual output) or the sound (audio output) from your device

The wrong adapter cable is being used or your current cable is not functioning properly. Make sure you are using the proper cables with their matching utilities. For instance, the audio cable must be plugged into the audio ports and speakers for the sound to work.

Ensure your display can be used with the ultra-low resolution of the Commodore 64.

Ensure the cable runs directly from the composite port to the RF modulator , and it is tuned to the channel you are using. The slider is used to tune within that channel.

The Commodore 64 's 3-4 pin composite output from the DIN video out connector is non-standard and requires a compatible monitor.

RAM or RAM multiplexors may have failed. Unfortunately the only way to locate bad RAM is to swap them one by one unless one is hot.

The VIC chip handles all video is a known failure point and is usually socketed. Make sure the replacement is of the same part number as there are a few revisions.

Replace the character ROM.

SID chip might be faulty. Replace SID chip if both symptoms are present.

Check the PLA chip.

Check solder joints on joystick ports or another joystick.