Modified a RCA XL100 CTC108 TV w CH CM7000 inside

[old_tv_nut]

Nice!

Did you have to amplify the luma or chroma, or did you get what's needed due to not terminating the outputs?

[wa2ise]

Originally Posted by old_tv_nut

Nice!

Thanks all.

Originally Posted by old_tv_nut

Did you have to amplify the luma or chroma, or did you get what's needed due to not terminating the outputs?

The luma and chroma signals were about the amplitude needed, unterminated. You can get away with doing that as any reflections bouncing off the unterminated far end of the connecting coax cable gets absorbed by the source termination (the 75 ohm resistor located at the signal source).

Ended up using an audio isolation transformer on the audio from the CM7000 CECB. The deflection yoke magnetic fields gets into everything, and this transformer breaks a loop to avoid excessive buzz in the sound. This loop includes the luma and chroma cables from the CECB to the chassis.

Used the TV's original volume control's power switch as a master power switch that unpowers the set and the CECB. I noticed that CM7000's can go into la-la-land if left in standby for weeks on end. If that should happen, I can turn off all power with this switch. Left the CECB's top off to allow for better cooling of its boards.


Added a plastic light pipe to direct the LED light from the CM7000 board to a point in the center where the VHF knob used to be. So I can see the status of the CM7000 board, green = on, yellow = standby and rest of set off, red = power up boot. Black = all off.

More screen shots showing a lack of cross chroma, below a pattern on the collar that gets cross chroma with a line comb:

And a lack of cross chroma (look at the close together strips to the left of "Fox Sports") you'd get with a notch filter: