Trying to bypass the tuner in an Emerson PC6.
 

I've got an Emerson PC6 5 inch color TV that i am trying to bypass the tuner on. Found the video out from the tuner IC:7530AN (Pin 16), but when i cut the trace and feed my video signal into Transistor Q101, i get either no picture or a black and white picture, depending on if i send it direct to the transistor or through the filter connected to the transistors base.

I have attatched a schematic from the service manual, is there an easy way to inject video with color?

Could it have anything to do with the video signal being at 4.4V from the tuner?

Here's a bigger version of the service manual.
https://imgur.com/a/NHsQG6X

USUALLY Q101 is the first IF amp, dont inject there.
To inject composite video at 1V P-P you need to find the video out
pin off the jungle or IF IC depending on if they are separate IC's.
Schematic to small to read otherwise I could help more. Also
part of it is shaded making matters worse.

the IF output is pin 16, i have uploaded bigger schematics to imgur.
https://i.imgur.com/NLKBVOx.jpg

Looks like the IF stage has a video out, it's an LA7530N.
https://pdf1.alldatasheet.com/datash...O/LA7530N.html

the only video input is on pin 25 of the LA7601W. but, the video also snakes off to the deflection circuits as well .

Video out of LA7530 is pin #16
Try unsoldering #16 & injecting onto the PBC

Tried that already. it results in a black and white image.

OK well done so far.
Good news is Sams has the manual ( redrawn neatly ). Bad news is
I dont have it. New scan of schematic better but I still cant read.
At this point either they are taking the color off before this point or
you have a color problem. If you have a VCR, game or generator
with RF out it will narrow that down.
IIRC I had a similar set with no color & it was a low ohm ( 1 or 2 ohm )
resistor feeding B+ to an IC. Look into that. Maybe someone on the list
can post the Sams, its MUCH easier to follow. Its # 2640-1

73 Zeno
Merry Christmas !

I know that when i feed it RF from my snes, or via an rf modulator, i get full color video. worse comes to worse, i'll just shove a modulator inside.

Sorry for a late reply, i don't get on here much. anyways, i found the sams for the set. here's the link: https://files.catbox.moe/dfg87z.pdf

weird host, I know. I use it for reddit stuff, it's a safe link.

If you got a scope look at the video on Q101 emitter & compare
between RF input & direct. All I can think of is its not big enough.
Otherwise you got me on this one.

73 Zeno:smoke:
LFOD !

I'll take a look then.