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CRT pinout?

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currentkills91

Tue Apr 03 2012, 08:49PM

Registered Member #3831 Joined: Thu Apr 14 2011, 02:54PM
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Posts: 265

Is there a way to determine the pinout of a CRT tube? I have this little one from an old pocket TV I tore apart, and I wanna use for making a small "oscilloscope" basically. Obviously it wouldn't be really useful, but I found a few schematics online for drivers and things like that, but without knowing the pinout of my CRT it's kinda hopeless. I would just use it to see gate waveforms to see if they look the way they should. I don't have the money right now to even buy a cheap second hand analog scope from eBay so please don't suggest buying one. any help would be appreciated :D

Here's a few pics of the CRT in case they help at all (MOSFET for size comparison)

Proud Mary

Tue Apr 03 2012, 09:30PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

TLY80602A is the part number of a Panasonic yoke.

The tube's own part number may be printed on the glass under the yoke.

Do you know if the TV was colour or black and white?

If it was monochrome, then it probably came from the Panasonic TR-1000 series, (1980 - 1984) and if colour, from the CT-101, which was produced only in 1984.

If the tube type number is not printed on the glass under the yoke, then identifying the TV model number will be the key to identifying the tube, and hence the pin-out.

currentkills91

Wed Apr 04 2012, 01:20AM

Registered Member #3831 Joined: Thu Apr 14 2011, 02:54PM
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Okay, I should be able to remove the yoke assembly rather easily? It came from the TR-1020P which was black and white.

I will remove the yoke, and see if there is a number. I should've guessed there might be a number under that x.x

Conundrum

Wed Apr 04 2012, 06:52AM

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

I wouldn't remove the yoke without first making marks with a CD marker on the tube ABOVE THE YOKE so they don't rub off!! this will help realignment later.

I also have a "flat" CRT here if its any use, tried to turn it into a 'scope tube but you need the plates inside the glass not painted on the outside unfortunately.

Also there are PIC based 'scopes, 12F675 and outputs B/W video.
Not very high bandwidth but there are ways around this, such as the heterodyne + lowpass filter method.
For even higher frequencies use a TV tuner, frequency counter and 20 turn trimpot on the tuning diode.

-A

Steve Conner

Wed Apr 04 2012, 07:07AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

This is a magnetic deflection CRT, fun to play with but pretty much useless for making an accurate scope. You certainly won't be able to view gate waveforms.

The simplest driver circuit is the TV that it came out of.

currentkills91

Wed Apr 04 2012, 11:51AM

Registered Member #3831 Joined: Thu Apr 14 2011, 02:54PM
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I did a fair bit of google searching and found a lot of examples of decent "scopes" made from CRT's like mine. They dont have any grid or anything fancy, but are claimed to work into the MHz range. I just need something to see if the signal is square, triangular or sinusoidal. It doesn't have to be perfect, just something I can use to test the drive signals to see if they are usable.

I managed to easily get the yoke off, very simple, but going in I didn't know that. lol I didn't find any numbers or letters though :( So My guess is, is the part number was on that little sticker maybe? If so I have no idea how to find the pinout...

Steve Conner

Wed Apr 04 2012, 12:04PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

There are plenty of small CRTs that look like yours but actually have electrostatic deflection. (you can tell by the absence of yoke coils)

Yours is magnetic deflection and certainly won't work into the MHz range or display waveforms properly, unless you built a very specialised amplifier for it. (and you'd need a scope to troubleshoot the amplifier

)

Proud Mary

Wed Apr 04 2012, 01:13PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

It seems likely that your CRT is a Panasonic 40HB4, which survived the pocket TV era, and had a new lease of life as a viewfinder in video cameras.

Unfortunately, none of the usual datasheet sources - Datasheet Archive and Frank's Electron Tube Data, two of my favourites - have a sheet for it that I can find.

Failing a datasheet, you can often work out the pin connections by careful study of the interconnections you can see through the glass (where this is possible). The simplest pair of pins to identify are the heaters, which will be the only two pins that have a low resistance between them - in an undamaged tube. (Of course, you'll not be able to find them with an ohm meter if the heater has failed open-circuit, as does happen with thermionic valve failures.)

currentkills91

Wed Apr 04 2012, 02:04PM

Registered Member #3831 Joined: Thu Apr 14 2011, 02:54PM
Location:
Posts: 265

Well the TV worked just fine, I just didn't like how sensitive it was. (with tuning) I have been rather gentle with it since I took it out, so it shouldn't be damaged. Although I have noticed, and it's visible in the first pic, there is a piece of white stuff broken away from the rest of the gobs of it. Does that white stuff do anything important? If anybdy even knows what I'm talking about.

And hmmm, well I suppose it would be cool just to build something to be able to view waveforms. If it doesn't work good enough to view waveforms I'll just use it for a "spectrum analyzer"? for my stereo, it would be kinda neat.

So the goal is, use google and my eyes to try to figure out the pinout, and then build a driver circuit for it(:

Thanks for all the help guys!!

klugesmith

Wed Apr 04 2012, 11:09PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

currentkills91 wrote ...

And hmmm, well I suppose it would be cool just to build something to be able to view waveforms. If it doesn't work good enough to view waveforms I'll just use it for a "spectrum analyzer"? for my stereo, it would be kinda neat.

Have you done that yet? Put the CRT back in TV system and get a raster. Disconnect the horizontal deflection - now you have a vertical line as the spot scans top to bottom. Now drive the horizontal deflection as if it were a speaker. If you want a horizontal baseline, you can rotate the yoke (or the TV) 90 degrees. Or connect vertical drive to horizontal coil.

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