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Monitorisation of mono sets

 
MongooseDC
(@mongoosedc)
Member Deactivated Account
Posts: 75

I'm looking to "monitorise" some popular mono sets by feeding CVBS/audio into them. I think that as analogue broadcasts have now ceased, keeping these sets going with digital converters in them would be a way of keeping them alive for longer. It's increasingly difficult to buy digiboxes with RF out on them, so I figure that monitorisation is the method to use. What I'm proposing is for this thread to be a library of monitorisation mods we can all refer to. It was inspired by the thread on the 1400 where the discussion was about official monitor mods for 1400/1500 series chassis. Obviously with these "live" valve chassis there is an issue with mains isolation, with many of these designs being mains dropper power supplies. However on the later solid state portables, especially those designed to operate on 12V/240V, they are powered via a transformer, and many earlier monitors were variations of these chassis without tuners and RF/IF sections. Philips in fact produced a television set based on its V2001 12 inch monitor; it shared the same case and a similar chassis if I remember correctly.  For most people, it would be useful to safely bring out the baseband CVBS/Audio to a pair of phono sockets on the set's rear or side panels. I know for some people they don't like to interfere with the originality of a set; however I think it would be really great to see great noise-free pictures from digital sources on these sets, and the best way is to monitorise them! Sets that come to mind are the Thorn 1620 series. It may be that some of you might remember some official monitor modifications (for school or broadcast use) as has been suggested in another thread. 

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Topic starter Posted : 05/11/2018 1:55 am
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 11262

Hi Mongoose,

First of all let me state I respect everyone is free to pursue what they wish and do what they like to sets that they own. I equally understand that your single focus within this hobby and forum would appear to be "monitors", again that's your prerogative.

I will however try (I did say try) to be brief and add the following:-

You state that "modding" the likes of the Thorn 1400, 1500 and others will keep them "alive for longer". I must point out to maintain a balance of views, they don't need "modding" to be kept alive or useful for longer and I would not wish newbies looking in to think that is the case. 

The 1400 is a dual standard TV so if one could not afford a 625-405 standards converter it can be used on 625 with the aid of a suitable modulator. Likewise the 1500 being 625 single standard, is equally as easy to supply due to an abundance of modulators and source devices. So sell it for what it is, an area that fascinates you and floats your boat.

You say you were inspired by the recent 1400 thread, I fear then you missed the whole point of Brian's detailed efforts and in fact all our efforts here and I might add including your fave 'Shango', that being we all promote "repair and preservation". Don't get me wrong, I do accept there are many sets out there, many already in the hands of owners who repair and maintain them as they should be, if you "mod one or two here or there its hardly going to have an impact. I equally accept that basket cases can be ideal projects.

Trevor (murphyv310) has done some amazing and creative work with a TV22 which was beyond restoration. His projects with this set have yielded some fascinating work and its had some interesting development (Jelly-pot lopt, Sony TV9/90 CRT to name just two) ideas, should parts be unavailable to keep TV22's going. A few frowned upon what he was doing and were quite rude about it but they failed or chose not to see the set was beyond normal repair, so was an ideal candidate for experimentation and not a "crime".

 

Finally, I would point out you have posted about "monitoristion" multiple times, across multiple threads, you may have noticed with very little feedback or input from this community. In fact two members have found it totally unacceptable making it very clear to me in a number of ways (pm's etc) how they object, finding it odd that you choose to pursue this activity on a site and forum that is "alleged" to be dedicated to the "preservation" of vintage electronics. If you fail to get much input I hope you will understand that few will be interested in your path as many find the concept you are pursuing at odds with "their" goals and this sites mission.

That all said don't be despondent, this is not and should not be an elitist community where so called "heretics" are burned at the stake for daring to go against the grain. As I mentioned at the start of this post, you are free to pursue the challenges you want and I wish you luck but equally you must accept it for what it is and know that you're blazing a minority trail. If you're happy to beaver away pursuing your interest, not forcing the issue in other folks threads, then I see no problems with you tinkering in your corner of the forum on a project that interests you and if folk chip in all well and good.

I have moved your thread from the "B&W TV repair/restoration" section and placed it in the "workshop" section. I don't think it is suitable for the "B&W repair & restoration section", it is more suited as a workshop project topic.

If anything this post might at least spark some useful debate for you.

Regards
Chris

 

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Posted : 05/11/2018 7:58 am
mfd70
(@mfd70)
Active V-Ratter Registered
Posts: 228

One of my first TV projects was to modify an old Thorn 1590 portable to accept a video input from an Acorn Electron computer, I can't remember the details, but I didn't fully appreciate that the video bandwidth of this little TV was not really suitable for an 80 column display even bypassing the RF section. Still, I was only 13 !

Unfortunately I'm always seeing nice old TVs on ebay, which I don't want, but fear will end up gutted and used as furniture, even an antiques dealer I was asking about old TVs assumed that I would be fitting modern flat panel chassis to old sets.

I think that perhaps fitting a baseband video and audio to an old TV is certainly not the worse thing can could be done to it. In fact, a real future proofing project (Freeview will be gone in 5-10 years) would be to fit an internal Raspberry Pi with wireless module to an old set. Though I suspect the composite video output on the newer Pis will soon disappear.

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Posted : 05/11/2018 11:00 am
Nuvistor
(@nuvistor)
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Posts: 4143

Monitors I occasionally repaired in the 1980’s had a video bandwidth or around 12Mhz, these were character based not graphics. Can’t be certain of the resolution but 80 characters wide seems to ring a distant bell.

Very sharp and easy to read, phosphors were one colour of the customers choice either green, amber or white.

 

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Posted : 05/11/2018 1:32 pm
MurphyV310
(@murphyv310)
Reputable V-Ratter Registered
Posts: 363

Hi.

Today it's still possible to run a 625 line UHF set without the need to alter the set. Both Beta & VHS video recorders have a modulator that will give a suitable RF output for the set. On E to E the video can be fed from a freeview box to watch normal programming. Older freeview boxes still are around with modulators inbuilt. There are still many older video recorders that are essentially scrap with worn heads and other faults with perfectly good modulators that can be removed and used standalone for a neat solution. 405 is a different kettle of fish, a standards converter is really the only sensible answer, 405 line video tapes work but you need a system A modulator and someone to record the tapes in the first place. It is possible to feed the set with baseband signals on 405 from a VCR, I don't recommend this approach for at least two reasons. Safety is number one, due to the majority of sets with a live chassis, so it's vital to have isolation, the other thing is 1v P-P is insufficient to drive the grid of the video amplifier properly, so a small amp is needed. 

My advice is if money is tight is to make at least a system A modulator, the David Looser one is good, it's also easy to make a valve one using two EH90 valves and use 405 line tapes. Frank's Hedghog, has to be the cheapest solution right now and it is brilliant.

I'm with Chris and not an advocate of modifying TV'S to a monitor, of course it's each to their own and no one should tell you what to do with your own possessions. Sad thing is when you see a collector smashing up items rather than selling or giving them away, at least you won't do that will you?

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Posted : 05/11/2018 3:43 pm