My CTC-16XL Project.

[Yamamaya42]

That did not work too well.

I tried to wire in a IF section bypass switch at TP1 ( point B) by running a video wire from one end of L9 to a switch on the back of the set and back to the grid of the first video amp, so I could switch between Ext video and video from IF, but the Tuner video was too washed out/ weak, I guess the video lines too and back from the switch added too much resistance for the IF input to work correctly.

External input works great though!

Next time I have the chassis out, I will just have to stick a relay at that point to get it to do what I want, same with the Audio,

Right now with ext video, I tap audio into the volume control R1 at point 30,( V8 Removed ) but I have to boost it by several Dbs or it wont be loud enough , pulled down by inactive sound circuts through c53, I'm sure if I also put a relay to switch in audio and cut out that cap, I wont have to boost it so much.

[old_tv_nut]

Originally Posted by Yamamaya42

That did not work too well.

I tried to wire in a IF section bypass switch at TP1 ( point B) by running a video wire from one end of L9 to a switch on the back of the set and back to the grid of the first video amp, so I could switch between Ext video and video from IF, but the Tuner video was too washed out/ weak, I guess the video lines too and back from the switch added too much resistance for the IF input to work correctly.
...

Not likely a resistance problem, but too much stray capacitance with the long wires. A relay would still be the fix.

[Yamamaya42]

Originally Posted by old_tv_nut

Not likely a resistance problem, but too much stray capacitance with the long wires. A relay would still be the fix.

It's also probably best to get the right KIND of relay, power vs signal, though in this case may not be ultra critical, it still may make a difference. Choosing, Mouser 653-G5V-1-DC12 when I DO plan to do it, I already have the +12v from my video amp.