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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 9th Sep 2017, 3:50 am   #1
Argus25
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Meet The Mummy & Dual Standard.

I'm still working on a 1987 vintage avionics video monitor and finding more and more astounding things about it.

On another thread I posted a circuit it contains for an outstandingly well performing black level video clamp, I finally figured out how it worked, it is clever and unique.

Today I went to replace the CRT and when I removed the existing CRT I found that the neck of it was all bound up with fibreglass insulating tape, like an Egyptian Mummy. I have attached a photo. Obviously it helps clamp down the yoke at one point, but it made me wonder about a remark on another thread that if there is an arc from the yoke assembly to the neck, the tube can be perforated. Apart from any mechanical reasons I wonder if this is why they insulated the neck ?

Since no circuit is available for this set I had to painstakingly copy out the whole thing. I've attached the vertical deflection & sync sep circuit. Notice how the vertical oscillator is a UJT.....Why on earth did they do that I wondered ?

Well, I found out today, the UJT circuit has an enormous lock in range, it turns out the set is dual standard (but there is no detection or switching for this). Also the set has no external H or V lock controls either. Both the H & V oscillators lock perfectly to monochrome NTSC or PAL signals ! there is a small height difference for the two signal types but that is it. The H flywheel circuit has a broad range too.

The yoke in this set is also beautifully made with integral raster geometry magnets.It is made by Syntronic Instruments. I've attached some photos and the circuit I traced out.

So this monitor keeps blowing me away with its innovations and build quality.
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Old 9th Sep 2017, 9:26 am   #2
Ted Kendall
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Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,658
Default Re: Meet The Mummy & Dual Standard.

That's aviation for you - there's probably a pedigree on file for every semiconductor in the thing as well. Nice kit!
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