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#1
02-16-2021, 02:55 PM
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B&K 1077B questions....Fixed
I decide to get my 1077b out as I am working on a GE 10T1 that needs trouble shooting. I picked this up a while ago and made a bad assumption based on limited test. I had previously turned it on an I got a nice purple glow on the front of the crt. I mistakenly assumed all is well. It is not. I tried it first on the the ge that has no picture an deiced i really needed to verify the 1077 works. I hooked it up to my admiral 19a11 and no image. Today I decided to look further into it and as it eats up a lot of bench top space I hooked it up to my flat screen (old non smart) via its cable/antenna connection. There is something there. The flat screen looks like it needs the horizontal hold adjusted. Since there is no such control on it I was wondering if there was a control or circuit in the 1077 would cause or adjust this? The video is a black//purple large rolling block that is about 30 percent of the screen height but full width and is separated by a large static block that would fill the rest of the screen height if not rolling. If I adjust the RF attenuation pot I can make the black//purple image disappear. The tvs input is set to antenna vice cable.
A few images below Andy Last edited by govee; 02-17-2021 at 01:32 PM. 
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#2
02-16-2021, 09:05 PM
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Since your flat screen set says weak or no signal even with the RF turned up, it is possible that either the B&K or the flat screen TV is set to the wrong channel, and the TV is trying to find the right frequency. Make sure your TV is set to broadcast mode, not cable mode.
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#3
02-16-2021, 09:08 PM
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Do you have the B&K lid closed? It will pick up ambient light (especially fluorescent) and produce horizontal hum bars in the picture.
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#4
02-17-2021, 12:43 PM
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I checked and channelization is correct. The tv is setup for air( I believe this is the same as broadcast). The image does not change with the top open or closed. I pulled the tubes one at a time on the video side of the device (not high voltage side) and there was no change to the image when any tube was removed.
Andy
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#5
02-17-2021, 01:32 PM
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I am not sure what kind of lesson I just learned as in most of my limited radio work tubes are rarely without obvious damage bad enough to make a radio dead. Not work well, sure. My inexperience probably let me call what I was seeing as closer to dead than I should have. I decided to check the tubes in the video side just to be able to answer the question of had I checked the tubes and V13 was completely dead. Filament good, no shorts, but zero emission on either triode (is triode correct?). I subed in a different 12at7 and the 1077B lives again. I added a picture with replacement 12at7.
Andy Last edited by govee; 02-17-2021 at 06:00 PM.
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#6
02-19-2021, 01:54 AM
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12AT7 is a dual triode.
No grid = diode. Single grid=triode. Dual grid= tetrode Triple grid = penthode or beam power tube. There were octodes...IIRC they were converter stages for superheterodynes.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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#7
02-19-2021, 12:14 PM
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Quote:
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#8
02-19-2021, 05:04 PM
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The old B&K makes a very nice picture on the modern flat screen. First time I've seen someone try that.
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#9
02-22-2021, 07:07 AM
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What model flatscreen is that? Or, the 1077 must have RS170 sync. I have never been able to get my 1076 to picture on anything digital. Or, maybe the newer Samsungs just don't care.
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Last edited by kf4rca; 02-22-2021 at 09:40 AM.
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Linear Mode
