Videokarma.org TV - Video - Vintage Television & Radio Forums

Videokarma.org TV - Video - Vintage Television & Radio Forums (http://www.videokarma.org/index.php)
-   Early B&W and Projection TV (http://www.videokarma.org/forumdisplay.php?f=19)
-   -   Motorola vt-71 restoration (http://www.videokarma.org/showthread.php?t=256916)

josephdaniel 01-23-2013 05:02 PM

.
Never mind

bandersen 01-23-2013 06:38 PM

Doubt it's just the 6SL7 tube causing your troubles. Waves could be some hum in the power supply. Do you have something like a B&K 1077 to inject signals into the video IF stages ?

josephdaniel 01-23-2013 07:01 PM

No I don't have any signal generator.
Is it ok if I used electrolytics in place of the film caps in the ballest?

bandersen 01-23-2013 08:10 PM

Are they non-polarized ? Ideally I think motor run caps should be used because they're designed to handle continuous AC current.

josephdaniel 01-23-2013 08:17 PM

Quote:

Originally Posted by bandersen (Post 3060121)
Doubt it's just the 6SL7 tube causing your troubles. Waves could be some hum in the power supply. Do you have something like a B&K 1077 to inject signals into the video IF stages ?

I havent replaced the filters yet (probably should have done that first... DUH

about the ballest I had the set on for a few minutes (longer than I have ever had it on) and I noticed the electrolytics were getting very hot and begenning to vent. Motor run caps would probably work good but arnt they in big sardine cans filled with toxic preservatives like PCB I know the old ones were not shure about the newer ones.

bandersen 01-23-2013 08:30 PM

Yikes! Yes, you need to use non-polarized caps. They stopped using PCBs in caps a few decades ago so no worries there unless you dig up some ancient ones.

I used a plastic film motor run cap like this in my Predicta Holiday. I've used regular film caps too, but I'm not sure how well they'll hold up under extended use.

http://www.digikey.com/product-detai...9401-ND/207387

http://media.digikey.com/Photos/Pana...SERIES_sml.jpg

josephdaniel 01-23-2013 09:42 PM

I will probably buy those soon since I plan to watch this tv nightly after i get it working!

bandersen 01-23-2013 09:53 PM

Be sure to check the dimensions before you do. They're too big to fit inside an original mesh metal ballast tube.

josephdaniel 01-23-2013 09:57 PM

I could probably stick em under the chassis if they don't fit.
Is there a way I could inject a signal in the if stages without a signal generator?

josephdaniel 02-14-2013 07:53 PM

bump...
I haven't been able to work on the set lately had a ton of school work but I did get the ballast fixed but it still does the same thing. anyone any ideas? even remote possibilities?

bandersen 02-14-2013 09:53 PM

Did you replace the filter and all the paper caps ? Are the ballast caps still getting hot ?

josephdaniel 02-15-2013 07:06 PM

no I replaced the capacitors in the ballast with film ones so it does not get hot anymore I got all the paper caps replaced except for one .004 at 600 volt cap and I have not replaced any of the filters yet bu I will probably get to that on Monday since I don't have school.

polyphase 02-18-2013 05:53 PM

Quote:

Originally Posted by josephdaniel (Post 3060014)
http://img.tapatalk.com/d/13/01/23/3a5ypuzu.jpg
The lines move side to side but those vertical lines are not there in person

That pattern looks like audio to me. Those tightly packed vertical lines would be the 4.5mHz FM audio subcarrier. Do the lines go away with no input signal? If so, I would be pretty sure of it.


All times are GMT -5. The time now is 04:50 PM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2026, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.