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Old 12-09-2018, 01:19 PM
Kevin Kuehn's Avatar
Kevin Kuehn Kevin Kuehn is offline
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Location: WI
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Originally Posted by AlanInSitges View Post
I mailed B&K about this thing asking if they had any documentation, and they told me they never made a PAL version.
That's funny. I hope you emailed them a picture of the impostor piece of equipment. Possibly there was another B&K division over near your country that made them.
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Old 12-10-2018, 04:11 PM
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AlanInSitges AlanInSitges is online now
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Location: Sitges, Catalonia, Spain
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Nah, I didn't bother, the lady mailed me the same schematic for the 1077 that is floating around the web.

OK, another day, more head-scratching. I probably picked a tough place to start this hobby, but I'm in it now and hopefully I'll see it through to the end. I really don't understand the architecture of this thing. On a high level yes, but getting down into detail I'm confused. This goes to more general TV circuits and not just the 1077. Here's my understanding, which is clearly wrong, no need to be gentle:

The horizontal and vertical oscillators depend on boost voltage (vs B+) for their plates. The boost generally comes from discharging a capacitor (which I don't see in the 1077) off the damper tube, which conducts as the magnetic field in the flyback collapses after the horizontal output tube stops conducting at the end of each scan line. So...if the horizontal oscillator is not running, there is no pulse on the grid of the horizontal output tube, which does not conduct, which does not cause the magnetic field in the flyback to collapse, which does not cause the damper to charge the capacitor, which means there is no boost so how does the horizontal oscillator start with nothing on its plate? I can see the chicken but there seems to be no egg.

Someone please straighten me out!
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Old 12-10-2018, 05:17 PM
Electronic M's Avatar
Electronic M Electronic M is online now
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The set starts on the 225v B+ supply which has a DC path from the boost supply back through the flyback then through the damper to the 225 rail.... the 225 starts it then once the osc starts switching the output generating boost the boost adds to the 225 it started on.

Voltage checks against the schematic are a good starting point in major failures like this.
Tom C.

What I want. -->

Reading between the scan lines since the mid 2000's.
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