Hello there. First time here, Noob.
I have an apple 2 that is driving me crazy. Problem is that i dont get color in HRG. I DO get color in GR.
I have studied the circuit and traced it out with a scope (best i can). Here is what i see.
The clock is spot on.
The divide by 4 at chip B1 is producing perfect 3.58mhz
Im getting 3.58mhz all the way through B13 and B12
the burst signal then goes to a 1k resistor before entering the 'color killer' portion of the circuit.
At the in side of this resistor i get the 3.58, on the out side it goes to hell jumping from khz to 5mhz.
It is NOT the color killer transistor, Q6 as i have removed this completely during testing so the path to ground is open.
The only thing along this path connecting to ground is a variable cap (have changed it and also tried a fixed cap of 47pf) a stand alone 47pf cap (have changed it) and a 27uh inductor (have lifted its leg at ground - got worse)
Then the signal goes up to a 2.7k resistor where it joins the NTSC stuff to drive Q3
So the section between the 1K resistor and the 2.7K resistor swings wildly. rock steady up to the 1K.
What am i missing? is this how it is supposed to work due to backfeed from the NTSC through the 2.7K resistor?
THANK YOU for any help you give.