C128 fixing video signal

Today I’ve decided try to fix the video signal on my C128. The video signal was not as bright as it should be.

C128 Video

I’ve decided to remove the RF modulator and use the RGBI output and replace it with a new one based on TSH7316 IC.

RF1 RF2 RF3

Documentation

Documentation

The module

Module Module1

After replacing the RF modulator with the TSH7316, the video signal is the same, so the problem is not the RF modulator :-). I will continue investigating the issue. Maybe the problem is in the MOS8701 chip or the VIC-II chip.

The MOS 8701 is a clock generator chip used in the C128. It helps to generate the video clock.