Quote:
Originally Posted by Yamamaya42
ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/
It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.  |
1) From the picture, you are only off by 3 or 4 cycles per 60 Hz, or 180 to 240 Hz. You should be able to adjust L31 (A16) to go through zero beat and be off either way, from a few hundred Hz too low to a few hundred Hz too high. Can that be done? If so, the system should pull in when you get close to zero beat. If it doesn't, the problem is in the phase detector or reactance tube circuit, not the oscillator. If you cannot go THROUGH zero beat to be off either way, there is a problem in the oscilator circuit.
2) I hope you meant your meter reads 3.48 MHz, not 34.8 Mhz, but even that is very wrong and does not correspond with the number of rainbow bands you are seeing. Forget the meter.
3) A 3.58 MHz crystal and a 3.579545 are the same thing, just stamped with fewer digits. The one you wouldn't want would be 3.56 or 3.59, which would be used in a gated rainbow generator, not a TV.