TV Oscilloscope

earth tones · Post by **earth tones** » Mon Dec 19, 2005 7:53 am

Anybody ever made this mod successfully around here?

There are a few sites with directions around the net, but I keep running into the warnings, and I wonder if this is really for people with no experience working with TV's. All of the components that can store a charge, and it is more than capacitors. There are components that can be drained, but will quickly recharge. Warnings about the CRT. I assumed, initially, that if I only touched what the instructions said to touch, that I would be ok. Since I will be working on a different tv than the one that the instructor was working on, how can I be sure that I avoid all possible threats.

Milkmansound · Post by **Milkmansound** » Mon Dec 19, 2005 8:06 am

its probably just easier, safer, and more intelligent in general to find an old scope and use that. I was a TV tech for 3 years, and if you do not know what you are doing in there (sometimes even if you do!) you can get bit pretty hard.

trust me, you do not want to mess around in there. Modifying a low voltage audio cirtuit is one thing, but a TV? Thats just insane: theres 30,000 Volts in there!

bitsyras · Post by **bitsyras** » Mon Dec 19, 2005 8:27 am

I was thinking about this the other day - I work in a car shop and what with the transition to smaller hand held diagnostic gear, there have got to be a lot of unused scopes/analysers laying around. Some are really huge, and others, well, less huge. Look in the tools section on ebaymotors maybe. Or ask your friendly local mechanic. That might be a shorter route to what you're after than killing yourself with an old TV. Plus you could get the dwell just right on your old Valiant...

-m

Milkmansound · Post by **Milkmansound** » Mon Dec 19, 2005 9:15 am

someone is selling a scope over on the prodigy pro forums for $50.

brianroth · Post by **brianroth** » Mon Dec 19, 2005 1:23 pm

When I was a kid back in the 1960's, I recall seeing DIY plans being sold in the classified section of Popular Mechanics, etc for a project like you describe. As I recall, part of the mod included rotating the CRT 90 degrees (!!) in order for it to work correctly.

Bri

lanterns · Post by **lanterns** » Mon Dec 19, 2005 7:30 pm

I think this is the scariest thread I've seen here so far.

It makes my teeth hurt a little bit.

DON'T GO IN THE T.V. MAN!

earth tones · Post by **earth tones** » Mon Dec 19, 2005 9:12 pm

This is one of the articles that I was referring to. All of the warnings are there, but I didn't really read it as such a threat. Even though I was aware of the dangers I guess I was assuming that he was attempting to instruct a novice. Perhaps this is aimed towards the television-familiar.

http://censtron.com/?p=18

It is too bad because I was about to do this. The only supply item I didn't have lying around was an old tv, which is a great start for a cheap diy project. I suppose the television selected would be the most important choice, now that the dangers involved are understood.

gyraf · Post by **gyraf** » Tue Dec 20, 2005 4:27 am

The page says quite clearly: "DO NOT ATTEMPT THIS PROJECT!"

And the resulting oscilloscope will be a very poor tool, as a magnetic-deflected tube like a television tube will lack anything resembling linearity at all but the intended working frequencies (50-60Hz Vert, 15-16000Hz Horiz.)

Oh, and you'll probably damage the phosfor on the screen by hitting it with electrons at a far-lower-than-intended speed..

Jakob E.

rolandk · Post by **rolandk** » Tue Dec 20, 2005 11:08 am

You should be able to find a good used scope for less than $100. Dosen't have to be fancy for audio. I just bought a B&K 20MHz 2 channel scope off of ebay for $90 including shipping and it works great.
Also, you can burn some test tones on a cdr instead buying a function generator. I use the headphone out of my cd player, which has an adjustable volume control.

lanterns · Post by **lanterns** » Tue Dec 20, 2005 6:42 pm

one time my friend was on acid and jumped into the T.V.
that was awesome

jpmorris · Post by **jpmorris** » Wed Dec 21, 2005 9:04 am

I think I have an Elektor article from the 70s to do something like this, but it worked by generating a signal for the TV, not by modifying the TV itself. I don't know how well it worked (whether it would work well enough to align tape decks, for example). I may have to dig that article out now.

earth tones · Post by **earth tones** » Wed Dec 21, 2005 10:00 am

I really did not intend to use this TV scope for measurement utilities, but more for visuals and performance. It just seemed like a really easy, interesting project.

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TV Oscilloscope

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