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Old 09-03-2017, 11:39 AM
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old_tv_nut old_tv_nut is offline
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p.243 of the red book (p.9 of the 630TS circuit description) shows the proper waveforms on the plates of the sync discriminator (on the left). Since the horiz is being locked, it must be developing the proper control voltage to the reactance tube, but somehow this is at the wrong phase.

Possibilities I could surmise:

1) The reactance circuit is screwed up and requires an offset input voltage in order to center the frequency (I think not likely, but...).

2) (I think more likely) The transformer that drives the discriminator (which you are tuning) is bad, or tuned way off frequency, or the .015 cap that tunes it is bad, and the discriminator is not being driven by a pure sine wave. I would check the waveforms on the sync discriminator plates to see how they compare to the redbook illustration.

EDIT: redbook p.268 bottom and p.269 top show actual scope waveforms - I see the pulse is much bigger compared to the sine wave than shown in the drawing on p.243, but the phasing is the same.
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Last edited by old_tv_nut; 09-03-2017 at 11:45 AM.
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