EEVblog Electronics Community Forum
EEVblog => EEVblog Specific => Topic started by: EEVblog on October 22, 2017, 11:40:46 pm
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Teardown of a 1989 Sony Watchcam Pocket Flat CRT video display monitor.
This ones uses electromagnetic deflection technology.
Compare it to the Sinclair FTV1 electrostatic deflection system
New intro and outro animation by Al Armandi
https://www.erwinscat.com/ (https://www.erwinscat.com/)
https://www.youtube.com/watch?v=65ENph8sV-0 (https://www.youtube.com/watch?v=65ENph8sV-0)
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That's quite a fancy logo animation. Nice!
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The video went down.
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Dave (or somebody) probably noticed an "Oops" of some sort - and has taken it down until fixed.
I expect it will be back up again in the next couple of hours or so...
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Some 3D work? Can't see (yet).
Luckily, no. It's a schmick but fitting animation that incorporates a few relevant things. You'll see :)
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Dave (or somebody) probably noticed an "Oops" of some sort - and has taken it down until fixed.
I expect it will be back up again in the next couple of hours or so...
The old video had the same number as the last John Kenny video.
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As I'm sitting here watching the video before it was taken down, I realized I have one of the "consumer" versions.
The weird little "4p multi" jack has a ~9 inch cable in it that terminates in a BNC female connector. Based on the connector size, I think my "home security" unit is a bit larger than the portable one. It also has no provision for batteries. Avg. power consumption per the label is 4.2 watts.
I opened it up just now, and interestingly it's quite different from the unit in the video... it's still electromagnetic, but the circuit boards are in the "lower half" and consist of two 1"x3" boards mounted at right angles to a main board that fills the lower half of the case. Even the glass tube seems different - the plate on top of mine has rounded edges. Made in March 1990 per the label.
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I always thought all solder thiefs have to point in the same direction.
The solder thiefs of the little puppy in this video have pointing them in opossite direction.
I had one of this crappy Casio LCD pocket TV's with a microscopic view area.
I bought it only view years after this thube-version was build for 500 Schilling (now ca. 50€)
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The long scan coils are horizontal scan, the round ones, vertical.
The rings on the neck are picture centering on a mono tube. On a colour CRT they would be the purity adjustment.
The inductor with the magnet adjust the relative width on the left and right hand sides of the picture. It does this by causing the inductor to saturate in one current direction. Fullsize CRT units usually have one with a rotatable magnet.
HTH.
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The inductor with the magnet glued to it; Isn't that a linearity coil, as every CRT TV used to have? A Grey Beard at Philips once told be about these components. As I recall, they are inductors with asymmetrical properties.
This topic also has a question about them:
https://www.eevblog.com/forum/beginners/magnetic-inductors-what-are-they-called (https://www.eevblog.com/forum/beginners/magnetic-inductors-what-are-they-called)
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Dave (or somebody) probably noticed an "Oops" of some sort - and has taken it down until fixed.
I expect it will be back up again in the next couple of hours or so...
I ( and maybe others) pointed out that that the inductor board was probably for geometry, and that might explain why it was on a seperate PCB, maybe it set up on a seperate test jig , so the PCB is probably specific to the individual CRT.
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the anode connection must be internal, the HV connection is located with the rest of the connections on the end of the tube
the phosphor also seems to be metalised on the back and there is a small nib at the centre of the phosphor screen that might have a conductive path back to the anode connection?
the reflective properties of the coating might also help brightness?
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This thingy, the linearity coil drowned me in nostalgia for evil voodoo of horizontal sweep circuits for a couple of hours. And after all, I found a photo of the most memorable version from my childhood.
(https://upload.wikimedia.org/wikipedia/commons/thumb/5/57/RLS-110L1.JPG/640px-RLS-110L1.JPG)
https://commons.wikimedia.org/wiki/File:RLS-110L1.JPG (https://commons.wikimedia.org/wiki/File:RLS-110L1.JPG)
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Dave you've dropped your usual high standards.
The CRT doesn't need an extra deflection stage because the phosphor is both curved and angled to compensate. The sinclair is both flat and parallel to the beam so it does need a third deflection stage.
It looks like it was CAD designed to me. routed then flood filled. PCB CAD was available from at least 1983 (for the one I used) and Sony would have had the budget for it.
Other than that great video
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the anode connection must be internal, the HV connection is located with the rest of the connections on the end of the tube ...
Odd that. Notice on Erik's version the EHT connector is in the expected location.
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the anode connection must be internal, the HV connection is located with the rest of the connections on the end of the tube ...
Odd that. Notice on Erik's version the EHT connector is in the expected location.
This sort of CRT was quite common in things like door entry systems, so quite likely they went through a few iterations over the years
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oscon capacitor. "OS = Organic semiconductor" That is a long time ago.
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Somewhere I have/had a WATCHMAN FD-240 version of this with a TV tuner. Won it a contest, I've been sort of looking around for it for a while but only found the box so far. Kinda useless now as the analogue transmitters are all gone.
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Well, here's your chance to build a portable ATSC conversion box, then :)
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I still see loads of these CRTs on door opening systems (the kind where you buzz people in).
A lot of buildings have a camera in the doorway so you can see the person in the street before opening the door. For some reason these systems don't use LCDs yet.
I guess it's because they're simply sending a composite video signal from the camera to the receiver instead of trying to use some digital protocol, with all the expense/problems that would cause.
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seen them displays too, reminds me of the first video camera tubes. that used 45 degree offset electron beam. iconoscope
befor vidicon tubes. ;D
they say the Magic is in the two chip's the technology to fix electron beam raster distortion in a flat crt
perspective distortion of the raster. 15 or 80 degrees to the phosphorescent screen. your looking inside the tube, vs the outside.
however its monochrome b&w display as Color 3 beam tubes can not be made flat, as far as I know. :-//
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The inductors are linearity correction for the scan, though there typically with larger tubes will be some NTC and PTC thermistors in the yoke as well to do wire resistance compensation as well. the magnet offset on the coil is there to make the inductor have variable inductance with current, and yes it is set up for the tube, or at least set up for the tube type, being adjusted in the factory by having a fixed jig with a CRT displaying a test pattern with some chinagraph lines on the CRT face to show the correct linearity, and simply applying the magnet to the coil with wet varnish and turn and move till the lines align with the chinagraph as best as possible, hen remove and leave to dry on a non magnetic board with holes for the leads. This works for small CRT units quite well, as you can have a "typical" CRT used for setup and the producton ones will be close, or just use one per batch as setup unit. For larger CRT's they would hold a plastic printed mask in front of the CRT, and then adjust the linearity magnets, then stick in the small correction magnets ( those little ferrite magnets on long plastic arms that are under the yoke mounts) to get the alignment right and remove colour fringing across the shadowmask, then paint the whole lot in position with varnish on the CRT neck. If you ordered a new CRT it would come with a pre aligned yoke, or with a set of magnets and you had to do all that linearity and colour alignment yourself in a non magnetic area.