Quote:
Originally Posted by vts1134
. . . . . . I had prevously thought that the vertical was running too slowly but you can see now that is not the case. The horizontal white bands do not roll with this signal, instead they are steady right where you see them.
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VTS1134,
OldCoot is suspecting one problem, and he very well may be correct.
Let's stop and think about the problem.
I see the vertical section attempting to run at 120 cps and it is badly speed modulating the sweep resulting in dual white bands. In other words, the normal 60 cps sawtooth is being speed modulated by a two backwards steps at a frequency of 120 cps.
The wrong speed operation could be caused by either a 120 cycle hum being fed to it from the power supply or from some component in the vert osc/output circuit being badly off value. (A heater cathode short would introduce a single band. Only the 120 cps hum can create a double band and 120 usually is only found in a full wave power supply.)
1) I assume that you do not have a service scope. If you do, the first thing to check is the B+ and B- power supply sources for hum. Then check to see if the waveforms from the sync separator through the vertical output are correct.
2) Substitute the vertical tube. If you don't have a spare, switch the video output 6SN7 with the vertical output 6SN7 tube. If this changes your problem, then you probably have a bad vertical output tube.
3) Since you restuffed the electrolytics, you might check to confirm that no electrolytic can became accidentally grounded. None of the original electrolytic cans in either the power supply or the vertical section were grounded when RCA built the set.
4) Check every electrolytic in the vertical to make sure you have a close to correct value and it is wired in with the correct polarity. On the Riders on the ETF website, which I've copied in an attachment, the positive side of the electrolytic is always marked with the section marker (ie, the triangle, square or inverted cup). Especially, check C127B between the height control wiper and the 100K going to the wired end of the vertical hold. Another possible source is an incorrect electrolytic across the cathode resister of the vert output. Also check C131B at the vert output transformer.
5) If you had a real mess up in the front end of the power supply you would hear a rather annoying buzz from the speaker, as the field coil of same is used as the filter choke. (If you have a loud hum, then pull the audio output tube and if it continues, then there is a problem in the power supply.)
Hope something here helps.
James