Quote:
Originally Posted by Kevin Kuehn
So after changing all those bypass caps is your B+ back where it should be in the tuner and video IF circuits?
I can't remember if you showed us your tuner? I'm wondering if it's the standard coil type, and if so have you tried adjusting the local oscillator adjustment for the individual channel you're set to? If it has those adjustments they can be off enough that the fine tuning won't get you best picture and sound.
That contrast mod should work. Likely you can even use a 500 ohm pot. However you'll still need to set the rf/if gain for best operation as there is no AGC in this set. But you'll at least have separate gain control over video.
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It seems to be the standard tuner as it appears in the sams, I have not tried to adjust anything else other than the 1st IF at this point.
The voltages are up a bit more to where they should be, it seems that the voltages shown on the riders (& rca 630ts service manual docs ) are misleading, after looking at it for some time, it hit me, how can the voltage on the plate of the 1st IF tube be @ 135v, if the source bias is 135v, going through 3 150 ohm resistors and 1 1k one? It can't be...
It must be wrong.
Sams shows it to be 95v
And sams shows the (135v) to be 117v.. :/
mine are now very close to that, so I guess the voltage was mostly OK to start with.
But still, when I tried to go “by the book” to adjust the 1st if, it did not work right.
1) remove osc tube, did that...
2) DC probe at junction of R40-R41, adjust “contrast” to -3 volts, leave it there.
This did not work, it cut off all input from tuner/if , no input defection at all, had to take it up to -1.2 to get it to do anything, and when I did try at that point, it ended up worse than when I started.
It was this point I replaced the WHITE waxy caps, and re-adjusted 1st IF visually, to get to where I am now.