Commodore 64 control port fault. Reapr log. breadbox64.com

Assy 250425 Rev. B #1

This machine is an Assy No. 250425 Rev. B long board.

Commodore 64 control port fault. Reapr log. breadbox64.com

The machine would boot normally, but Control Port 2 showed faults using my 64 Doctor Cartridge. Nothing happened when pushing fire, right or left with a joystick.

Commodore 64 control port fault. Reapr log. breadbox64.com

The control ports are closely connected to the CIA chip at U1 (MOS 6526). I therefore started checking the physical connections (traces) from the control port to the chip as I’d previously ‘cured’ a faulty Control Port by exchaning this chip (link). All connections checked out OK.

Commodore 64 control port fault. Reapr log. breadbox64.com

I therefore replaced the CIA chip with a working one.

Commodore 64 control port fault. Reapr log. breadbox64.com

Commodore 64 control port fault. Reapr log. breadbox64.com

And now both Control Ports are working again and the machine is ready to do some gaming!

Commodore 64 control port fault. Reapr log. breadbox64.com

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