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Adam Munich

Tue Jan 11 2011, 04:59AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
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Lately I've been playing with the parts from my old sony watchman. I think it's just so clever how they made the tube flat like that.

I separated the crt from the board with 4 feet of ribbon cable, just to see if it would still work. It does work, very well in too. There's one thing though; the picture is "smudged to the right", as if the brightness of the scanning beam is changing a little too slow. I don't think this is due to the long wire because I remember the tv having the same issue in it's factory state. Anyone know what causes it?

Arcstarter

Tue Jan 11 2011, 05:02AM

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Location: Beaumont, Texas, USA
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That's awesome! Do you think it has a magnetized shadowmask that needs to be degaussed? (That was a shot in the dark...)

Also, i couldn't help but notice, Olivia is on the screen from the episode of family guy. Die hard fan, both me and my big brother.

Adam Munich

Tue Jan 11 2011, 05:42AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
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Black and white crts have no shadow mask.

Also, robot chicken > family guy.

The wavyness is line interference.

GeordieBoy

Tue Jan 11 2011, 01:40PM

Registered Member #1232 Joined: Wed Jan 16 2008, 10:53PM
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Neat! I'm surprised it works as well as it does with an additional 4ft of cable between the CRT and the electronics! The ribbon cable will add a lot of stray capacitance to the video signals, and this decreases their slew rate. Essentially limiting how quickly the brightness of the electron beam can be altered as it sweeps across the screen. This would definitely cause blurring of the image and smearing of features in the picture across the screen to the right.

I'm also suprised that the ribbon cable held up okay with the final anode EHT being fed down one of the wires! I'm sure standard IDC ribbon cable isn't rated for more than a few hundred volts. Be careful man

-Richie,

Conundrum

Tue Jan 11 2011, 03:28PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

i have a larger one of these tubes from a door camera kit, with a non functioning (damped) driver board.
I was going to convert it into a curve tracer but the tube alignment is a bit strange.

EDIT:- you could probably convert it to colour with a piece of the back glass from a surplus LCD panel, the alignment would be finicky and probably not worthwhile though.
-A

Adam Munich

Tue Jan 11 2011, 06:22PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Yeah, but the smudges appeared when the wire was short too. I guess that out rules the stray capacitance theory...

I figured that sending the HV down the middle of the ribbon cable would cause some issues, but it didn't. Probably because the electricity has an easier path to ground; the tube.

Adam Munich

Wed Jan 12 2011, 01:43AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Ok, so I cut off the power supply pcb and replaced that with an LM7806 (yes they exist). The extra volt made the smudges smaller and only noticeable on high contrast images.

That extra volt also over scanned the picture and made it too bright. The over scanning was fixed by fiddling with all the pots, but I had to put a 1M resistor in series with the brightness pot to darken the picture a little bit.

when I was holding it and watching some TV I noticed something very strange with this crt: the location of the image on the screen is dependent on it's physical orientation. Hold it one way it's higher up on the screen, hold it another it's lower.

The only theory I have is that the crt is sensitive to the earth's magnetic field, probably due to the extreme angle of the gun relative to the phosphor screen. Odd.

ubuntupokemoninc

Wed Jan 12 2011, 02:56AM

Banned on 1/22/2011 for repeated rule violations after multiple warnings.
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Sweet!!! now you can watch your favorite shows and eradiate your self from the x-rays

Adam Munich

Wed Jan 12 2011, 03:00AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

5kVp x-rays can't even make it into my body, let alone out of 4mm of leaded glass. I feel safe watching this thing.

James

Mon Jan 17 2011, 12:23AM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

Smearing is usually indicative of a weak CRT causing the video amp to clip. The long cable will cause it too, but if it was already smearing you probably have a weak tube or your anode voltage is low.

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