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HINTS & TIPS HE 112

 

Q
I have a Loewe Planus (100Hz) television and a Toshiba SD-2109 DVD
player. On some discs a thin green line (and sometimes red) that can be seen at the top of the TV's picture. This happens on the main film disc, but strangely doesn't occur on the disc featuring the extras, which has the same visible picture proportions. Also, this only seems to occur on films that use the full widescreen processing, not those that produce a letter-box picture. Is this a problem between my DVD player and TV?
P Clayton, Twickenham

A

Compatibility problems with DVD players and TVs are actually quite rare and normally affect every disc rather than the odd one. In this instance the most likely explanation is a slight mis-alignment of the TV’s convergence circuitry, which is responsible for ensuring that the red, green and blue images are precisely aligned. The reason that it only shows up on widescreen movies may have something to do with the fact that DVD extras are usually in 4:3 format. The TV electronically expands the picture to fit the 16:9 screen and the change of shape usually results in some slight ‘overscan’, which puts the top few picture lines, where the misalignment is most visible, off the of the screen and out of sight. The simplest way to find out is to substitute the TV or the DVD player; if the TV is responsible it should be a simple job for an engineer to sort out.

 

QUICK TIP

The convergence adjustment on a TV is usually carried out using an electronically generated grid or ‘crosshatch’ pattern of fine lines. When the convergence is set correctly the lines appear white, any misalignment shows up as a coloured ‘fringe’ or offset line from the grid pattern. Incidentally the famous Test Card F – the one with the young girl in the middle – has two convergence test patterns: a white grid for the outer edges of the screen, and the game of noughts and crosses on the blackboard for the centre-screen area.

 

 

Q
I recently bought a Toshiba Picture Frame TV, as recommended in HE 98, and I've noticed a slight buzz that increases with the picture brightness. The dealer tells me it's due to the coils vibrating and that this is "within normal operating parameters". They also told me this happens on all large screen TVs these days. This noise is only noticeable during quiet dialogue, but nonetheless it's still distracting. Can you tell me whether I should expect buzzing from such an up-to-date TV or whether I have been sold a duck?
Paul Smith

A

The dealer is right about the noise being generated by the TV’s deflection coils, he might also have added that noises can come from the EHT (extra high tension) components that generate the high voltages used to drive the picture tube. The tube itself can crackle and make hissing sounds in very dry or excessively humid conditions, mains power supplies hum and whine and the horizontal scanning circuitry generates a high-pitched whistle; in other words most TVs are far from silent (see also Getting Started). However, exactly what constitutes ‘normal operating parameters’ is open to interpretation, but you shouldn’t notice any noises at living room volume levels. If you feel that your TV is excessively noisy you have every right to insist that something is done about it but before you do, listen to a few other TVs, preferably under similar conditions, to make sure you haven’t become overly sensitive to this one noise.

 


Q
I have a Bush DVD 2004 player coupled via and S-Video connection to a 28-inch Sony TV. When playing Monsters Inc. the player displays all of the menu options but won’t allow me to access them so it stops after three seconds. At first I thought it was the fault of the DVD disc, so I replaced it, three times, and none of them have played. In the end I had to resort to buying the movie on VHS, for the children's sake, but I'd much rather see it on DVD. I have about 15 Disney DVDs and they've all been fine. Can you help?
Jason M Clary

A

There have been a few reports of compatibility problems with this movie, though to date most of them have concerned layer change on Pioneer players. This sort of thing used to be quite common in the early days but both disc producers and player manufacturers seem to have got their acts together and there have been very few incidents lately. However, before you take the player back, run it through with a disc cleaner, just in case there’s dust or fluff on the optical pickup (though this usually causes problems on all discs); you should also confirm that it really is the player and not the disc – just in case all the copies you’ve tried were from a dodgy batch – so try it out on friend’s player or ask the shop to check it out.


QUICK TIP

A lot of early DVD compatibility issues concerned layer change where the player’s optical pickup was unable to switch focus quickly enough, (or at all), to read the second data layer on some DVDs. Most recent problems have been to do with various players inability to read or process the increasing amount of PC multimedia content that’s appearing on discs. In most cases the problem has been solved by updating the player’s ‘firmware’ (the software that controls the player), either by playing a special disc or by swapping a microchip inside the machine.

 

 

 

Q
I have a Grundig Digibox and if I set it to RGB output the picture moves about 3mm up the screen. This is particularly annoying when watching football, where the score is positioned at the top of the picture. Also, when watching Sky's cricket coverage, the blue info bar at the bottom of the screen becomes very prominent. However, if I change the output to PAL and suffer the poor quality, the picture is positioned fine. I had the engineer round, but he said it was a "transmission problem". Any ideas?
Ed Bowden

A

That sounds like a fairly typical fob-off line from an engineer who either can’t or won’t fix the problem. In theory there shouldn’t be any difference in position between pictures from composite, S-Video and RGB feeds. In practice it’s difficult for TV designers to avoid and there is often a very small displacement but it should be never be enough to cause the kind of shift problem that you have described. There’s a very small chance it could be down to the digibox but it’s far more likely that the TV is need of a tweak, it may not be possible to eliminate the shift completely but a good engineer should be able to adjust the picture geometry (see also Getting Started) to minimise or compensate for the effect.

 

 

 

Q

I’m thinking of buying a Pioneer DCS-303 system. I have just read some reviews and have a few questions.

1. The DCS-303 has Dolby Pro-Logic II; does this mean that if I record
(using a VHS recorder or a DVD recorder) or watch in stereo on the TV, I
will hear it through all five speakers?
2. When the price is reasonable, I want to purchase a DVD recorder. Will
I be able to plug it into the DCS-303 and still use it as a home theatre set-up?
3. Can I use my VCR with the DCS-303? I'm still recording movies off the
TV and I'm wondering whether when I play it back the DCS-303 will
provide sound from five speakers?
Robert Fleming.

A

1. Pro Logic II creates a stereo rear channel from Dolby Surround soundtracks, so yes, you will hear sound coming from all five speakers (front stereo, front centre, rear stereo surround).

 

2. Yes, you’ll be able to plug a DVD recorder into your DCS-30, it has an optical bitstream input, so you’ll hear Dolby Digital and dts movie soundtracks in all their glory through your system.

 

3. Yes again, the DCS-30 generates a 5-channel surround sound from 4-channel Dolby Surround and even stereo and mono sources but in the case of the last two the effects on the surround channel will be artificially derived. Pro Logic II is a very clever idea but the fact remains that what you are hearing is a fake, and it will be up to you to decide whether or not the effect is pleasing.

 

 

Q
I have a Panasonic TV that has one SCART connection, a Panasonic NV-FJ630 VCR and a Reoc A3 DVD player. I bought a five-way SCART
adaptor and a second SCART lead but when both leads are connected to the adaptor volume brightness is reduced. If I disconnect either lead while using the other the sound and brightness go back to normal. I don't know if this is to do with the adaptor or the SCART lead?

Shiranthi

A

It sound a lot like the SCART adaptor is to blame and there are a couple of possibilities. You may be using the wrong type, there are basically two options: there are simple ‘splitters’, where all of the plug and socket pins are wired together in parallel, and ‘switchers’ where only one input is connected to the output cable at a time. A splitter is designed for signal distribution, i.e. one input with several outputs, so if it’s used incorrectly, in an ‘input’ mode, the signals will interact with one another. The other possibility is that you are using a switcher type adaptor, but there’s something wrong with it, or it’s a flaky design, that’s affecting the AV signals, or allowing them to interact. If the adaptor is an expensive item, from a reputable brand you should take it back, otherwise a new ‘switched’ adaptor is called for.

 

QUICK TIP

SCART switchers come in a wide variety of shapes, sizes and capabilities. The cheapest ones have a simple manual mechanical selector switch, or a row of push buttons, which is obviously inconvenient as it means you’ll have to keep getting up out of your seat to change inputs. The alternative is an auto-switching type that senses when an input is active and routes the AV signals to the output cable. However, if your TV only has one SCART socket it’s probably getting on a bit and about time it was replaced… 

 

 

 

Q
I have recently invested in a Miller & Kreisel K3 speaker system (3 x
K7s, 2x K5s) and have partnered this with a REL Q150E subwoofer. I'm
very happy with my buy, but I do have a problem. I used to have a Yamaha YST-SW40 sub that had an auto-off switch, which shut the sub off when not in use. I know these are often frowned upon, but I found it very useful. The REL I have now doesn't have this feature, and the instruction manual says the sub will be fine if it's left on continuously. However, the worrying thing is when any other appliance in my house is switched on or off at the mains, the REL omits a 'thud'. Is there something wrong with it and will it do any harm?
Ian Forster

A

It’s probably not a fault but it may suggest careless design. It’s unlikely the odd thud will do any damage but if it’s happening a lot, or they’re loud then you should definitely put a stop to it. It’s likely that the sub is reacting to momentary high voltage spikes that ride around on the back of the mains supply. These are unavoidable and are caused by appliances containing motors or inductive components switching on and off. Spikes and surges can also be generated by the supply grid and even lightning strikes but wherever they come from the power supplies in most mains powered AV devices should filter them out. If, as seems likely the sub’s power supply isn’t dealing effectively with the spikes then you should try an anti-surge/spike mains adaptor. They’re cheap and plentiful and readily available from electrical and electronics retailers, computer stores and even good old Woollies.   

 

QUICK TIP

A few sub woofers with auto power have come in for some stick, not because the feature is inherently flawed or that it affects sound quality, but it’s all down to timing. In an ideal world a powered sub will switch on more or less instantly, as soon as it senses a signal from the amplifier or decoder, and switch off soon after the signal has disappeared. Getting the switch off delay right is crucial otherwise a powerful sub, with the wick turned up high, can be left emitting an annoying hiss for several minutes.

 

 

Q
I recently bought a Philips DVDR 890 DVD recorder, there was a glitch so I took it back and it was exchanged but the second one was the same. The problem is when recording from VHS camcorder tapes through the EXT2 (SCART) connection the results are, at times, appalling.
  The picture is very bright and saturated with colour and little detail. I've tried using different tapes, various video sources, two cables and three types of DVD+R disks but I'm ending up with a lot of coasters. Philips Customer Care suggested feeding the source via the TV and recording from that using the EXT1 SCART and this appears to work but the only problem is you cannot view anything else while recording.

Chris Martin

A

The fact that Philips came up with such an oddball (albeit effective) solution suggests that it’s something they’re well aware of and just before we went to press Chris contacted us to say that Philips had advised him that the problem was being looked at and that he should return the player and request a refund…

 

It’s looking increasingly likely that this is inherent in the design, possibly something to with the machine’s Macrovision copy protection system, which is meant to stop users running off DVD copies of movies on tape. If that is the case there probably isn’t an easy or quick solution though if anyone out there has got a DVD-R890 and one of those so-called ‘copy enhancer’ gadgets that strip out Macrovision protection they might like to try a few experiments to see if that solves the problem, and don’t forget to let us know how you get on.

 

 

QUICK TIP

It hasn’t happened yet but as and when recordable DVD takes off it’s likely that there will be a rapid influx of cheap and unbranded blank discs. The CD-R/RW market is awash with the stuff, much of it second-rate and there’s even a suggestion that manufacturer’s rejects are turning up on bulk buy ‘spindles’, labelled as top grade media, and sold at Computer Fairs. At the moment only a small handful of plants around the world are making DVD blanks and so far the quality seems to be fine but watch out for deals that look too good to be true…

 

 

BOX COPY 1 – TV PICTURE GEOMETRY

Ensuring accurate picture shape or geometry on a cathode ray tube (CRT) display has been an enduring problem for TV manufacturers. One of the most difficult things to get right is linearity, which is a measure of the picture’s horizontal uniformity. In other words, if you were to look at a picture of a ruler on a properly set up TV the markings would be evenly spaced but if the linearity is out of bonk the ruler will appear to be stretched or compressed along its length.

 

Correct linearity on a 4:3 TV is not too difficult to achieve but it’s been a headache for manufacturers of large 16:9 widescreen sets. That’s because the image is ‘drawn’ on the inside of the screen by a moving beam of electrons, streaming from a ‘gun’ in the neck of the tube. The beam is moved around the inside of the screen by a powerful magnetic field, generated by a set of coils mounted around the neck of the tube. The wider the screen the harder it gets since the speed at which the beam traverses the screen has to be precisely varied, to compensate for the changing distance between the gun and the screen, because it has further to go to reach the outer edges of the screen, compared with the middle.  Linearity, like convergence and focus can all drift as the tube and the electronic circuitry ages, which in the past meant that a TV required regular servicing. Nowadays most TVs automatically compensate for the changes and usually require little or no adjustment throughout their normal working lives, which is typically 6 to 8 years. 

 

 

BOX COPY 2 – NOISE ANNOYS

With the notable exception of LCD panels almost all video display devices make some sort of noise. The loudest noise in a cathode ray tube (CRT) television is undoubtedly ‘line whistle’, though the good news is that it becomes much less of a problem as you get older. The whistle is produced by the TV’s deflection coil circuits, which oscillate at around 15kHz. This frequency is just within the human hearing range – normally cited as between 20Hz to 20kHz -- though once we get past 25 our sensitivity to higher frequencies drops off sharply (markedly so in men, which suggests that women should make better music and hi-fi reviewers…). 

 

Of the alternative display devices on the market CRT, LCD and DLP video projectors are the worst offenders because all models have large and powerful fans or extractors that have to run all of the time, to cool the high-intensity lamp. Many rear projectors – in particular LCD and DLP types -- also have cooling fans but naturally ventilated CRT models generate a line whistle and have high voltages flying around inside that can produce crackles and hisses. You’d think plasma screens might offer some relief but no such luck, many models have cooling fans – some early ones had half a dozen or more of them – but even more recent panels that rely on convection cooling and ducted vents still produce high voltage crackles and contain large, gently humming or whining mains power supplies.

 

 

 

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Ó R. Maybury 2002, 0711

 

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