Was Testcard F problematic for 405 line and/or monochrome TV's?
Richardcoulter
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AIUI, when BBC2 went colour, they started showing Testcard F.
I also remember seeing it on our 405 monochrome set as a child on BBC1, i'm guessing that BBC1 adopted in when they too changed to 625 line colour.
At this time most people still had 405 line monochrome; yet their TV's were being calibrated, repaired etc using a 625 line testcard designed for colour.
Which got me wondering if this was a problem for the television trade?
Maybe the local 405 line masts opted out of national trade test transmissions to show Testcard C?? I don't recall seeing this though.
I also remember seeing it on our 405 monochrome set as a child on BBC1, i'm guessing that BBC1 adopted in when they too changed to 625 line colour.
At this time most people still had 405 line monochrome; yet their TV's were being calibrated, repaired etc using a 625 line testcard designed for colour.
Which got me wondering if this was a problem for the television trade?
Maybe the local 405 line masts opted out of national trade test transmissions to show Testcard C?? I don't recall seeing this though.
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No. TCF had all the components required for setting up 625 and 405 line receivers.
The only slight problem, was that the highest frequency grating on TCF would have been unresolvable on 405 sets, but not really a serious issue.
All this is covered (as always) by Alan Pemberton's website, which I always provide a link for in threads about test cards, so here we go again...
http://www.pembers.freeserve.co.uk/Test-Cards/Test-Card-Technical.html#TCF
There was an announcement at the time, essentially that the geometry and grey scale still had meaning, but the gratings were irrelevant.
How do TV engineers use the gratings etc? I've often wondered what all the lines meant.
After playing with the TV once, I found that there was a hidden border around the testcard (triangles etc). I wasn't sure if these were meant to be shown, so put it back to what it was!
I assumed that this was to indicate to TV engineers that the picture was not correctly set and was showing too much to the viewer.
That border round the edges is the overscan area, its not an issue now especially on LCD screens, but on older CRTs it was useful to hide the blanking areas.
Ive heard that years ago if anyone saw a bit of black on their screens they would call the engineer out, so some of the picture was overscaned deliberately to prevent callouts for that type of thing. Also with the older 405 sets the picture could be unstable and expand and contract.
These days on an LCD screen there is none of these issues so its perfectly fine to watch it in fact I leave my TV setup to show that area as much as I can.
I wouldn't worry too much though as any important information is kept within a safe area especially for on screen graphics.
Oh and the frequency gratings are for sharpness, you never want it too sharp else it would look odd but at the same time you want it sharp enough. I guess test card F made that hard work on a 405 set but a good engineer would likely know how to overcome that issue.
That was poor EHT regulation. Not restricted to 405 line sets, it was always a problem, on many sets right up to demise of CRTs.
The reason for overscan was mainly to hide horizontal timing errors, which could build up on multiple studio and tx paths, (and totally beyond the control of the viewer). Now everything is digits from camera to receiver, these are very rare, so it's safe to switch overscan off, although you do often see a pixel wide border of foreground/background because some vision mixers and DMEs allow the 'leakage' of the 'next' image.
LCD screens haven't allowed overscan to be reduced per se.
The first five gratings on TCF as seen on 405 lines, were within the system's passband, and should have been visible. Just a case of accurate tuning, and adjusting the focus (assuming the tuner and video stages were lined up correctly)
In fact, the resolution was better on b/w sets than colour. The combination of the sub carrier notch filter, cross colour, and the CRT's shadowmask or grill made the final two or three gratings difficult to resolve.
It's reckoned to be about 70,000 hours!!!
Here's some information about Test Card F:
http://en.wikipedia.org/wiki/Test_Card_F
And about Carole herself:
http://en.wikipedia.org/wiki/Carole_Hersee
The staff of each store consisted of a manager, a female cashier, at least one salesman, an engineer and a driver! Such luxuries! But we sold a lot of products and there was a considerable TV rental base. One of our rental sets was the notorious Ultra 1775, where there were often complaints of the picture rolling. I think the cure was often just the replacement of a PCL 82 valve.
In fact it got to the stage where our engineer, (same age as myself) would sometimes arrive at a house, whip off the back of the set, replace the valve, put the back on again and make as if to leave, without checking the TV. "Reluctantly" he'd turn it on and of course the problem was cured. However with at least two pensioner customers he had a problem of a completely destroyed frame hold control. both gave the excuse that they'd "screwed" it in as far as they could but it wouldn't catch against the picture to stop it rolling!
Customers weren't quite so fussy in those days, you weren't always guaranteed to get a decent picture with any set due to problems with the signal.
One little old lady for whom he fixed her rolling set, didn't seem to be bothered with the inch gap she'd had at top and bottom of the screen, for some time. She was quite pleased that he left her with a full picture!
We're used to no "customer usable controls" on many TVs now, but in those days there were physical controls for brightness, contrast, width, height, linearity, focus and frame hold and possibly more. Customers were expected to use these as valve set components weren't as reliable is is modern technology.
Digressing a bit, there were a lot of West Indian immigrants who'd come over to work on the buses and tubes. All were in rental properties, some just renting a room. It seemed quite sad that they had very little in the way of furniture or domestic appliances, if any of the latter, but as customers, they were polite and well mannered. Their most frequent purchase "on the drip" from us, was the Bluespot stereo radiogram, the one with the cocktail cabinet!
Our office TVs were all maintained by Granada Rentals, the Red Arrow men as we called them, Red Arrow being the original name for Granada Rentals, had many similar stories. If the transmitter went off air or even if there was a power cut, some customers would twiddle all the tuning presets and then demand a call out to reset them. They also did all the city centre hotels, it's amazing what they found stuffed through the rear vents of the sets in a very upmarket hotel. (Hint made of rubber).
Those were the days when these guys had a soldering iron, some diodes, resistors and capacitors, as well as valves, in their tool box. They were "proper engineers."
I remember when "the man" came to fix our first, single channel, TV he had two small suitcases One had boxes of spare parts, the other contained rows of valves in their boxes. He had a huge soldering iron that in winter he would push between the red hot coals in the grate as it took an age to warm up if he had to plug it in. It was a KB 12 inch TV, I don't remember it going faulty that often.
I wonder if TV engineers still exist in this throwaway age??
I imagine they do, but they are likely as they always were, also conversant with audio sets. There is a global community of enthusiasts who want to keep their 1950/1960s radios, record players and radiograms (phonographs in the USA) going. A lot of it is "self help," but there are people who specialise in rebuilding these well loved items. But a lot of them are getting rather long in the tooth.
I'm into vinyl jukeboxes, I've two. I can perform the regular maintenance routines, but if I've ever a problem beyond my capabilities, I could call on a local specialist engineer I know, who used to maintain them for a manufacturer/retailer.
Trouble is, he's 89 now.
For modern TVs, I think they are more "card changers" but that in itself does need some knowledge and skill.