B&K 1077B "Vintage TV" Questions - Page 2 - Videokarma.org TV - Video

Chris K · #16 09-17-2023, 08:08 AM

Well try as I might, the 1077 is still the same way it was when I first powered it up. I bought another one same model so maybe between the two I can make a functional one. Thanks everyone for your advice and suggestions. Stand by for more

DavGoodlin · #17 09-18-2023, 02:02 PM

Good luck, my 1077B has a vertical height problem and if I encounter a similar issue, I will post it here.

bandersen · #18 09-18-2023, 02:09 PM

I went back and too a fresh look at your photo. The color is right and there won't be anything on the screen. It should just be a purple box.
The only issue I see is you have some diagonal lines. That's why I was thinking the horizontal freq might be off.

Should look like this

While you have this. Have you tried installing a slide and displaying the output on a TV?

Chris K · #19 09-19-2023, 10:05 AM

No I have not yet hooked it up to a TV and tried it. I will. Thank you for defining what the screen should look like. I was going for a full screen. Shango did a 1076 a couple of weeks ago and it looked like he had a full screen but, of course, that could have been camera artifact.

Yamamaya42 · #20 09-19-2023, 10:46 AM

I had access to one of them in the 90s when I was working in a TV repair shop, and I remember being impressed at what it could do, I sort of remember it having a full screen raster, but I'm not 100% sure, it's been a while since I have seen one.
https://www.radiomuseum.org/images/r...77b_897561.jpg

random pic found when searching.
But yeah, good idea, hook it up to a good TV, see what you get! :P

bandersen · #21 09-19-2023, 01:08 PM

Don't worry about the size of the screen - that's not really important to it functioning.

Do you really have banding/folding/twisting as it appears in your photo? That's a bigger issue.

jr_tech · #22 09-19-2023, 02:14 PM

The “keystone” shape of the raster may be caused by a bad yoke... perhaps you could swap the yoke from the second unit to see if the shape of the raster changes.

jr

old_coot88 · #23 09-19-2023, 03:54 PM

Subbing the yoke looks like quite a hassle. My very first thought on seeing the image http://www.videokarma.org/attachment...4&d=1694521711 was a very large ripple(hum) on the main B+ line. Even if the main filter caps have been replaced, possibly a miswire(?) could be allowing a large ripple (since the vert sweep is locked to the powerline freq., a ripple would be stationary instead of a "crawling hourglass". Before doing a yoke swap, I would first want to verify that the main B+ is clean. Do you have a schematic for the unit?

old_coot88 · #24 09-19-2023, 04:33 PM

Duh. Just found the schematic. Main B+ goes to pin 2 (damper) of the 33GY7. You could jumper an electrolytic from there to ground and see if it affects the distorted raster any. 47 mf or thereabouts.
https://antiqueradio.org/art/BK1077BSchematic2.jpg
https://antiqueradio.org/art/BK1077BSchematic1.jpg

kvflyer · #25 09-20-2023, 06:52 AM

I don't think that it is keystone shaped, rather a distorted raster which some have addressed above. Instead of changing the yoke, you might want to try to find out what is going on with that raster.

Chris K · #26 09-20-2023, 07:59 AM

I have had some suspicions about the yoke but I agree, it's something I would change as a last resort. I think I'll try the jump to ground with the electrolytic from the 33GY7 to ground.

Chris K · #27 09-20-2023, 08:00 AM

Quote:

Originally Posted by old_coot88

Duh. Just found the schematic. Main B+ goes to pin 2 (damper) of the 33GY7. You could jumper an electrolytic from there to ground and see if it affects the distorted raster any. 47 mf or thereabouts.
https://antiqueradio.org/art/BK1077BSchematic2.jpg
https://antiqueradio.org/art/BK1077BSchematic1.jpg

Thank you for the links to the schematic!

Chris K · #28 09-20-2023, 08:05 AM

Quote:

Originally Posted by bandersen

I went back and too a fresh look at your photo. The color is right and there won't be anything on the screen. It should just be a purple box.
The only issue I see is you have some diagonal lines. That's why I was thinking the horizontal freq might be off.

Should look like this

While you have this. Have you tried installing a slide and displaying the output on a TV?

Wanted to try the operational test last night but I was finishing (finally!) a monstrous week long task of installing a 26KW standby generator for our house. I never want to work with 1/2" cable again. I'll try it tonight.

kf4rca · #29 09-20-2023, 08:38 AM

I don't think it's yoke. I picked up a really nasty 1076 once. It was out in the weather behind a tv shop that closed in a shopping center. The yoke was OK. After cleaning it up, I did have to change some electrolytics and 2M resistors.

kf4rca · #30 09-21-2023, 10:46 AM

Its easy to make slides for these.
Download your favorite test pattern or image, It should be about 333x444 in size but you can resize it in your paint program.
Print that image to an ink-jet printer in B&W. It should be about the size you want for the B&K.
Take that print to Staples or Office Depot and have them print it to a transparency. Ask for extra contrast if necessary.
They will print it on a laser printer to the transparency film. The last one I had done cost about 60 cents. Cut down to fit.
If you print to transparency film on an ink-jet printer, the image will rub off.