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All the radio tests that Wa2ise recommended performed as expected. FM radio tunes to dead quiet at the very center of "loud" on either side. There is a noticeable lull but not dead silence in the TV set at "dead on" signal.
The TV cannot tune any FM stations on channel 6 around 88.3 mHz, but unfortunately neither can my FM radio (nearest station is 89.1).
The 6AL6 filament is at the same 6.3VAC as the other tubes in the sound IF strip. The Sams voltage chart says that's how it should be. The 4.7-ohm resistor R48 doesn't appear to be significant enough to drop the voltage downstream. I'd be interested in the equation that tells me what the resistor should do. I guess it limits some current to some degree. It measures 4.2 Ohms with an el-cheapo digital Ohmmeter, about 4.0 even with my old trusty analog read-the-needle one and my nearsightedness.
The Sams chart expects 0.1 VDC on pins 1, 2, and 5 of V11 (schematic 3 posts ago). With VCR input I get 0.024 on pins 1&2, 0.054 on pin 5. With my signal generator as described earlier, I can tune a maximum of 2.81 VDC on pin 5, when the tone is at its loudest. It drops off abruptly as I tune the signal generator away from "dead on" point. Hangs out around 0.025V when the signal generator is tuned well away from the target frequency.
I can understand pin 5 having DC, and varying with signal strength. If there's an AC source on pins 1 and 2, pin 5 will be the rectified component of pin 2. Smoothed by C5.
But I don't understand why pins 1 and 2 should be at a positive DC potential. Where is the source? But without understanding why, it's still troubling that I'm at 24% of the recommended daily allowance.
The Mouser electrolytic cap tests fine.
Everything sure looks wired up right and within resistance tolerance. I don't know, maybe it really is an alignment issue. There's an antique fixit shop 90 minutes from here that specializes in TV alignment. Maybe I should "know when I'm licked" and take it in.
Anybody out there have a schematic for a Sencore PS148 Vectorscope? I'm sure mine is broken in an obvious way and could be repaired easily, with a schematic.
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