AVForums

Our philosophy in our forums, reviews, podcasts and feature videos is to promote audio and visual excellence by gathering and sharing the best information and resources available.

Help

To begin please visit our help section »

Not a Member Yet?

It only takes a minute to start enjoying the benefits of AVForums membership, and it's free!

Member Log in

Technical Problem (advice needed)

Post Reply
Old 17-02-2003, 6:25 PM   #1
mrdave21
Guest
Posts: n/a
Question Technical Problem (advice needed)

Hi all,

i am hoping that someone will have the expertise to guide me in the right direction as to what is going on. I have a Teac 51 cm TV (basic CRT), which has begun to output very poor picture quality. Basically, the problem is that dark colours come out WAY TOO DARK, to the point that some scenes (ie night scenes) are unwatchable. the problem also manifests in that faces are unrecogniseable (in most cases). To illustrate the problem, the blue-background the set has to unprogrammed channels (ie. where 'snow' would otherwise be), has at its worst, appeared black.

The picture is generally fine for lighter colours, except occasionally they appear too bright- eg. people's faces will apear a bright orange instead of skin colour, or grass is very bright green. This makes for very strange viewing especially when combined with the accentuated dark's described above!!

The only way i can watch the TV atm, is to put the brightness up very high, like 90/100. However, i do not really see this as a permanent solution, since it really shouldn't be that high.

I am by no means an expert on AV stuff. i bought a surround sound system (kenwood) a few weeks ago, and admittedly, have had 2 100 watt bookshelf side speakers, and a 100 centre speaker quite close to the TV set (ignorance!). The archives suggest that this might cause "deguassing" (?) or "doming", however, the symptoms commonly referred to, dont seem to appear in my case. Usually people complain of coloured patches on the screen, or fixed discolouration. I have neither of these problems, simply that dark colours are way too dark (almost like there is no contrast amongst dark colours). Also, i have tried the suggested remedies, by turning the set off, and removing the speakers- however, the problem remains.

Given the above, can anyone think of what might be the problem. I apologize if it is something simple and obvious, but i really just dont know. Thanks,

Dave.
  Quote
Old 17-02-2003, 7:57 PM   #2
mrdave21
Guest
Posts: n/a
the specs, if they add any meaning are

TV: Teac CT 5150H

DVD: Kenwood DVF 3060
Amp: KRF-V4060D

Speakers, 100W Kenwood Speakers, LS-V120W

I also have a PS2 hooked up to the above.
  Quote
Old 18-02-2003, 12:10 AM   #3
Veteran Member
 
Chris Muriel's Avatar
Join Date: Jun 2002
Location: Manchester
Experience Points:
15,693, Level: 30
Points: 15,693, Level: 30 Points: 15,693, Level: 30 Points: 15,693, Level: 30
Activity: 13.6%
Activity: 13.6% Activity: 13.6% Activity: 13.6%
Thanks: Gave 510, Got 629
Posts: 6,244
Sounds like a fault in the TV tube's drive circuitry ; you need an engineer familiar with that TV to tell you much more as not all CRTs are driven in the same way.

Chris Muriel
  Quote
Old 18-02-2003, 10:07 AM   #4
mrdave21
Guest
Posts: n/a
Thanks, i guess i was also wondering whether i could have in any way caused this problem with the speakers being positioned too close to the TV (the middle speaker is on a shelf just below it, and left-right to either side, half a foot away). Could this be like the first signs of a degaussing problem?? Or does it sound like something more related to the tube circuitry, unrelated to the speaker positioning?? If so, what other signs might there be that the tube circuitry is stuffed (ie. if there are any- the colour problems may be conclusive/obvious in itself????)

i read somewhere that the middle speaker should never be positioned below the set. Is this true??

Thanks, and sorry for all the newbie type questions. If there is a faq or something that might be useful to me, could someone point me in that direction as well.

Dave.

BTW- what exactly is "doming"?? My searches have only revealed scant information.

Last edited by mrdave21; 18-02-2003 at 12:46 PM.
  Quote
Old 18-02-2003, 7:29 PM   #5
Senior Member
 
fraggle's Avatar
Join Date: Dec 2002
Location: Milton Keynes
Experience Points:
9,636, Level: 23
Points: 9,636, Level: 23 Points: 9,636, Level: 23 Points: 9,636, Level: 23
Activity: 0%
Activity: 0% Activity: 0% Activity: 0%
Thanks: Gave 37, Got 17
Posts: 1,316
If it was magnetic staining this would affect the colours, not the brightness/contrast levels.

Check the contrast hasn't been wound all the way up and the brightness dropped a lot.

If everythings as it should be and you can't get a good picture by adjusting brightness/contrast it does sound like a tube drive circuit fault.

Depending on the age of the TV this could be just the excuse you're looking for to buy a nice shiney new w/s set
  Quote
Post Reply



Thread information and display options
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off