Quote:
Originally Posted by miniman82
Here's what I've been able to find out, so far there are nice sine waves arriving at the 6AL5 and everything looks normal- that is still I put the plate cap back on the HO tube!
Here's h-drive and h-sine with the plate cap removed and no signal input to the chassis, everything looks normal:
And now with the plate cap on:
See that little hump? Apparently the flyback is causing it to show up, so effectively it's self triggering because that pulse has more amplitude than a regular sync pulse does- so any sync pulses from a normal video signal applied to the chassis simple gets drowned out.
I'm still waiting for the flyback tuning capacitor to show up from mouser, so I won't know if the lack of it is what's causing this till it arrives. I really hope that's it, because I'm out of ideas here.
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Here are my thoughts, FWIW:
I don't see any explicit connection from the flyback. (correct me if I missed one on the schematic).
Assuming no intentional connection:
Where exactly is that sine wave and spurious pulse? On one of the 6AL5 plates, right? (pin 2 or 7).
Both good and bad waveforms are with nothing attached to antenna input, right? If so, you should try again with a good signal input. See if you get the sync pulse superposed on the sine wave properly then, and check both plates to see if you have same polarity sync and opposite sine wave. Look for the spurious pulse IN ADDITION TO the sync when connecting/disconnecting the HO. Maybe the HO is oscillating back into the tuner. If so, you need to see if the spurious pulse is still there when you have a good signal. If it's still there, that's what you need to chase. But if a normal signal swamps out the spurious pulse, then the bad phasing is still caused by something else.