General Forum

Re: pitching for high hopes.......

jahur — Thu, 25 Aug 2011 03:18:17 GMT

hi keith, thanks for that, the picture is totally faultless, its as strong as ever.

jason

Re: pitching for high hopes.......

Keith Saunders — Thu, 25 Aug 2011 03:14:53 GMT

jahur:

many thanks for your reply, ok ill break it down like this

1. yes

2. no, just through the rear grille, if im looking at the grille its coming from near top right.

3. short time after switch on, disappears then returns then stops and may come back

4. no

5. no, it goes when switched off.

Based on your answers I would say that the most likely source of the high pitched whistle is the "Line Output Transformer" which produces the high voltage for the anode of the tube. The line output oscillator runs at just over 16 Khz which generally speaking only younger people can hear faintly, but a faulty LOPT can make it very audible to most people.

Other than the high pitched whistle, is the picture perfect or has there also been some recent chnages to the quality of the picture ?

Re: pitching for high hopes.......

Keith Saunders — Thu, 25 Aug 2011 03:07:49 GMT

folkdeejay:

Faint lines are visible behind the picture, most visible on on darker images, ( hard to say on light images - say BBC news 24 studio shots, or an outside, daytime image) they runing horizontally across the screen in a sort of stretched S shape....(may be called scan lines, seems to ring a bell??) and I think they are the precurser to a failed tube .

I regret to say that this is almost certainly the tube on its way out. You are seeing the "Flyback" lines which are normally not visable except if the brightness is turned up beyond normal setting. Reducing the contrast/brightness a little will reduce the visible problem for the viewer, but clearly does not solved the core issue.

Re: pitching for high hopes.......

jahur — Wed, 24 Aug 2011 15:15:06 GMT

Keith Saunders:

Jason,

When you say you have an "annoying high pitch" coming from the rear of the AVANT, can you say what kind of noise, is it

a high frequency whistle

Can it also be heard in the speakers ?

Is it always there all the time or only for a short time after switch on ?

Does the sound come on instantly you switch on ?

Does the sound continue until you switch the TV off or does it fade after a time ?

hi keith

many thanks for your reply, ok ill break it down like this

1. yes

2. no, just through the rear grille, if im looking at the grille its coming from near top right.

3. short time after switch on, disappears then returns then stops and may come back

4. no

5. no, it goes when switched off.

hope this helps keith, look forward to your reply

jason

Re: pitching for high hopes.......

folkdeejay — Wed, 24 Aug 2011 11:19:53 GMT

Hi Keith,

Kind of related... I have an avant 28dvd that has an impending tube failure, I think.

Faint lines are visible behind the picture, most visible on on darker images, ( hard to say on light images - say BBC news 24 studio shots, or an outside, daytime image) they runing horizontally across the screen in a sort of stretched S shape....(may be called scan lines, seems to ring a bell??) and I think they are the precurser to a failed tube .

Any tips about mending the 28DVD apreciated ..is it an adjustment issue or is the tube about to die ??

Re: pitching for high hopes.......

Keith Saunders — Wed, 24 Aug 2011 09:39:14 GMT

Jason,

When you say you have an "annoying high pitch" coming from the rear of the AVANT, can you say what kind of noise, is it

a high frequency whistle
Can it also be heard in the speakers ?
Is it always there all the time or only for a short time after switch on ?
Does the sound come on instantly you switch on ?
Does the sound continue until you switch the TV off or does it fade after a time ?

pitching for high hopes.......

jahur — Wed, 24 Aug 2011 05:08:39 GMT

hi all, may have a problem with my 32 avant... all of a sudden i have this annoying high pitch coming from the rear of the avant.

any ideas as to what this may be?

cheers again all....

jason