Quote:
Originally Posted by old_tv_nut
Do you get snow with nothing attached?
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There's no snow or sound, only raster.
Quote:
Originally Posted by old_tv_nut
Is it possible your custom cable wiring is shorting to the cathodes of V1, so whether it works depends on the source being floating?
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I wondered about that, however running the pattern generator through the custom cable verifies it's working
Quote:
Originally Posted by Yamamaya42
All I can find is the schematic for the Dumont RA-108 , which I'm hoping is close enough.
Could it be perhaps that V1 RF amp is not working at all, or very weakly, and that the pattern generator in question is just putting out such a strong RF signal that it's able to blow past the defective stage, where the modulator lacks the power to do the same?
Lack of snow with nothing connected would be a clue of this, which is what I believe old_tv_nut alluding to.
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Good call, it's been a minute since I last had a look at it, but seems like I tried the old pull test to see what happened to the picture. With a pattern generator attached, the test pattern disappeared, but to your point yes it may just be passing the signal without amplification.
The print for this set is on Earlytelevision Foundation's web site, but it's a Sams which as usual and especially with this set isn't exactly a bastion of accuracy!