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  #30  
Old 04-17-2010, 10:09 PM
leadlike's Avatar
leadlike leadlike is offline
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Join Date: Apr 2008
Location: Lancaster, Pa
Posts: 956
You're right in that the 803 schematic is a close match. In fact, a lot of, if not all of the component numbers match up to my 802 schematic.

I spent another day hammering away at this thing. Primarily I was fooling around with that awful video noise producing that black blob of static on the edge of the screen. My scope traced the issue right back to the video input, and after tacking down another bad ground, I had a cleaner picture.

I also fooled around with v21's plate voltages, which should be about 230 and 245vDC. My set was only around 130 and 145 volts. I had to change the plate resistors quite a few times to up the voltage enough to this "stock" setting. It provided no difference in Horiz. lock, and only seemed to introduce some drive lines, so I went back to the lower voltage. The plate resistors (100 and 150k) seemed to be original, and were within 5% of their values. The 801 has lower plate voltages like mine...so mine is probably running properly. The waveforms are certainly clean.

I corrected a blooming issue by replacing a 470k resistor hidden inside of the 1B3's base (the 1B3 is mounted on 3 ceramic standoffs, the wiring in the base covered with a metal shroud).
So here we are:

GEDC0182.jpg

GEDC0181.jpg

I can now use the 6al5 properly, so DC resto is working pretty well. Retrace lines are visible, but I wouldn't be surprised if this set lacks vertical blanking. The picture still has a bit of waving to it, but it is extremely slight. I included the second picture, as it illustrates the only other issue I have with the picture-those faint vertical bars off to the left side. But, it's nice to have a watchable picture on this set.
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