Quote:
Originally Posted by Kamakiri
Now I probably shouldn't have done this, but I did it anyway.....without a scope available, I applied the "golden screwdriver" technique, and tweaked B6 all over the place, using the rest of the controls to try to tune everything in......
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If you have the original RCA notes or the Rider notes, you can find how to adjust the horizontal blocking oscillator transformer without a scope.
The RCA Synchroguide oscillator circuit used by RCA and others for over a decade is quite straightforward to adjust. It comprised of the oscillator tuning adjustment and a separate sine wave stabilization coil. In the earlier sets, these were mounted on the same coil form.
In this set you are first told to short out the stabilzation coil (I believe terminals C and D) and adjust (under the chassis) to frequency. Because it is a blocking oscillator it behaves similarly to the vertical blocking oscillator in the way it locks. The best lock position for the horizontal oscillator is to sync at just the point where the sync bar just disappears to the left with this adjustment.
After adjusting the oscillator, remove the short from C and D. Turn the horizontal hold to the far left, interrupt the signal and you should find the picture out of sync. Adjust the sine coil (from outside of chassis) so that about five to seven bars are seen before it pulls into lock. The adjustments interact so that you may have to go over it a few times.
You can tell if the sine coil is misadjusted: if the sine coil is adjusted to far one way you will get double triggering and you will hear a "chipping" sound when you adjust the horizontal hold. Too far the other way and the noise immunity is lost: verticals in the picture will look coggly on weaker or noisy signals.
I do not think there is likely a resistor problem. You need to ensure the oscillator and sine wave coil are set up correctly first. I would simply leave the locking range trimmer at about 1 1/2 turn from fully clockwise and see to the oscillator first. These adjustments all interact.
Try and find the RCA notes as they are pretty clear on how to do this. Also my memory is not as good as the written notes!