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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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29th Mar 2017, 12:30 pm | #1 |
Nonode
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,534
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'Shadow' on VHS machines playing 405
I bought my first VHS machine in 1982. It was a Fisher FVH-530 (if I recall the number correctly) and lasted for twenty years of regular use until it got 'sluggish'. I was then given a JVC HR-D180EK, which I have to this day and still works well enough. You may gather from this I have never got into servicing video recorders!
I have used both machines with my collection of 405-line VHS tapes. The picture is very sharp due to the less stringent bandwidth requirement on 405. Sometimes, on worn tapes the incorrect dropout compensation timing can be a pain, but I think of this like 'ignition interference'. On the later JVC machine, there is a faint shadow two-thirds across the picture. This is where the machine presumably expects the next 625-length line to begin. What internal feature is causing this? Has anyone done a survey of which machines do and do not exhibit this effect? Can anything be done about it? It never seemed to be reported on the early machines. Steve
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29th Mar 2017, 3:31 pm | #2 |
Octode
Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
Posts: 1,377
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Re: 'Shadow' on VHS machines playing 405
Hi there,
I recently experimented with a Ferg 3v29 vcr to record and play 405 material. There was a very noticeable shadow on playback. Gave a very good impression of 'Ghosting' though- quite authentic! After a bit of experimenting and a look at the circuit, it turned out to be the drop out compensator circuit getting confused. I just grounded the input to the DOC input on one of the signal processing chips and it all worked very well. If you need exact details, I will dig out the manual. I can't rightly remember if my 3v22 did the same but I don't think it did. I don't think it has a DOC anyway. Certainly my CV2100 ACE works (or used to before it spent 10 years in the barn) perfectly on 405. Cheers Nick |
29th Mar 2017, 4:53 pm | #3 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: 'Shadow' on VHS machines playing 405
I had ghosting similar to Steve on a Ferg 3V31, 3 or 4 years ago so nearly forgotten but I seem to remember this was to be expected.
John. |