Motorola vt-71 restoration - Page 2 - Videokarma.org TV - Video

josephdaniel · #16 01-23-2013, 05:02 PM

.
Never mind

bandersen · #17 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 · #18 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 · #19 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 · #20 01-23-2013, 08:17 PM

Quote:

Originally Posted by bandersen

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 · #21 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

josephdaniel · #22 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 · #23 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 · #24 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 · #25 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 · #26 02-14-2013, 09:53 PM

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

josephdaniel · #27 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 · #28 02-18-2013, 05:53 PM

Quote:

Originally Posted by josephdaniel

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.