Greenish Sony CRT TV

[dark666]

Hi all.

I have a Sony TV that displays a green transparent sort of filter over the picture.
I've tried to rotate the VR's that control RGB, no change on the picture, i can see the colors changing but the grrenish transparent filters remains over the picture.

Sometimes the TV works ok for a couple of minutes the the greenish color starts apearing from up do down, sometimes when i turn the TV it remains black with horizontal lines on the top of the screen, after a couple of seconds it displays green and the green display starts to fade until it stays transparent with the picture behind.

I'm thinking about malfunction of the microprocessor, the color control IC's.

Any thoughts?

Thanks in advance.

 

[Ian Rogers]

I had this on a Bush TV once... Virtually the same symptoms you described... The small PCB on the back of the CRT gun had degraded so much you could hardly touch it.. Delicately I re soldered all the connections I dared to... The lines went away but I was left with a softer green ( hardy noticeable ) top quarter of the screen.

Thrown it now... I bought my daughter a small LCD...

 

[Nigel Goodwin]

Try swapping the green and red (or blue) output transistors over, and see if the fault then changes to red (or blue) - leaky output transistors used to be pretty common back on Sony TV's. Next most common would be the CRT itself.

 

[cowboybob]

May have been stated, but too much green in a CRT display is generally caused by not enough (or no) red. Very common with CRTs.

Either the CRT red gun has, or is, failing, or the driver for it.

I'm with Ian.

 

[Nigel Goodwin]

May have been stated, but too much green in a CRT display is generally caused by not enough (or no) red. Very common with CRTs.

Either the CRT red gun has, or is, failing, or the driver for it.

I'm with Ian.

Perhaps you didn't read this part of his post:

green transparent sort of filter over the picture

Classic symptoms of a duff driver transistor on a Sony.

 

[tvtech]

Hi all

Put the set in front of me on my bench and I will fix it. Or please take a photo of the screen showing the fault. And post here.

Then I can maybe help.

No more comment from me. I don't guess. What the OP might be trying to explain is maybe not what is really wrong with the picture (as only a tvtech can understand, see and help solve)

Regards,
tvtech

 

[Nigel Goodwin]

No more comment from me. I don't guess. What the OP might be trying to explain is maybe not what is really wrong with the picture (as only a tvtech can understand, see and help solve)

Don't you see much Sony stuff? - his explanation was excellent, and perfectly fits an extremely common fault on Sony sets.

 

[tvtech]

Don't you see much Sony stuff? - his explanation was excellent, and perfectly fits an extremely common fault on Sony sets.

Hi Nigel

Zero new Sony stuff here.

Just the usual junk. I was one of last Techs that was trained to fix a Sony 191. With the Early Bird modification for the Power Supply and Line Stage.

We kept them gong until Screenvision ran out of Tubes that could be re-gunned.

That's life

Regards,
tvtech

 

[Ian Rogers]

I don't see the point..... The new Sony 32 inch LCD's are £240 from some outlets.... CRT's are hard on the eyes.... Spend £100 getting it fixed for about another 6 months.

Wasted cash IMHO.

I don't wish to sound harsh.. We're in a throw away society.

 

[tvtech]

I don't see the point..... The new Sony 32 inch LCD's are £240 from some outlets.... CRT's are hard on the eyes.... Spend £100 getting it fixed for about another 6 months.

Wasted cash IMHO.

I don't wish to sound harsh.. We're in a throw away society.

Hi Ian

The company I worked for in those days charged for Maintenance Contracts.
Sort of like insurance for your TV....should it pack up at your home. Heaven forbid lugging that set up and down stairs etc....

We would come to your home and repair on site

Regards,
tvtech

 

[Nigel Goodwin]

Zero new Sony stuff here.

'New'? - we talking an old Sony CRT set here

Funnily enough, the only South African TV I've ever seen (and repaired) was a Sony CRT one a good number of years ago - we were very amused by it, as it had an FM radio built in to give the second channel for stereo sound.

 

[tvtech]

'New'? - we talking an old Sony CRT set here

Funnily enough, the only South African TV I've ever seen (and repaired) was a Sony CRT one a good number of years ago - we were very amused by it, as it had an FM radio built in to give the second channel for stereo sound.

Those sets were known as "simulcast sets" where you could watch a TV program and tune in with the radio and listen to it in your preferred dubbed language.

Also very popular with live sport broadcasts....the same sport Video live...but with live reporting in various languages. People speak lots of different languages here in Africa.

The Simulcast part was a ball ache to fix on those sets...always an afterthought with wires added on from the Manufacturer etc. Thanks they are now history.

Not a stereo sound thing at all. We are still getting there

Regards.
tvtech

 

[davenn]

Originally Posted by cowboybob
May have been stated, but too much green in a CRT display is generally caused by not enough (or no) red. Very common with CRTs.

Either the CRT red gun has, or is, failing, or the driver for it.

I'm with Ian.

Perhaps you didn't read this part of his post:

Classic symptoms of a duff driver transistor on a Sony.

Actually Nigel,

the comments are totally valid, a green hue indicates that the Red gun or drive is not working too well
the fact that there is green there indicates that the green gun/driver ARE working
Im also with cowboybob I have seen that sort of fault many many times over the years of my TV servicing
The red gun/driver transistor are almost always the first to fail as the red tends to get driven more than blue or green

cheers
Dave

 

[Nigel Goodwin]

Actually Nigel,

the comments are totally valid, a green hue indicates that the Red gun or drive is not working too well
the fact that there is green there indicates that the green gun/driver ARE working
Im also with cowboybob I have seen that sort of fault many many times over the years of my TV servicing
The red gun/driver transistor are almost always the first to fail as the red tends to get driven more than blue or green

Again - you obviously don't repair Sony TV's - his fault description perfectly described the VERY common failure of one of the driver transistors, which go leaky on the old Sony CRT sets. I used to keep high voltage video output transistors in stock specifically for those sets.

This is why I suggested the entirely cost free, no test equipment required, and 100% effective, technique of swapping the green transistor with one of the other ones.

 

[tvtech]

Again - you obviously don't repair Sony TV's - his fault description perfectly described the VERY common failure of one of the driver transistors, which go leaky on the old Sony CRT sets. I used to keep high voltage video output transistors in stock specifically for those sets.

This is why I suggested the entirely cost free, no test equipment required, and 100% effective, technique of swapping the green transistor with one of the other ones.

And that is exactly why I did not get involved in this discussion wise old me... Swapping RGB transistors around is as you say cost free.

And good practice to find the faulty Transistor..

Still, no pictures. And the set is not in front of me on my bench.....so I am guessing too.

tvtech

 

[Nigel Goodwin]

And that is exactly why I did not get involved in this discussion wise old me... Swapping RGB transistors around is as you say cost free.

And good practice to find the faulty Transistor.

It's really the only way - generally on old TV's the output transistors go either S/C or O/C, so you just run the voltmeter across them - two will read 150V odd, and the duff one 300V or 0V - change the duff transistor, job done.

On a number of years of old Sony's they commonly go very slightly leaky, whilst still working as a transistor - so a simple voltage check doesn't help, but swapping the transistors over obviously does. To identify the particular colour you want, I used to place my finger on each collector in turn (the Sony transistors have a metal tab), and you will see that colour 'smear' on the screen - easier than looking the manual out

 

[cowboybob]

Again - you obviously don't repair Sony TV's

Well, in point of fact, no.

But every color CRT has (had) RGB guns and something to drive them.

Not having repaired a Sony, in particular, doen't disqualify the advice.

This diagnostic:

I used to place my finger on each collector in turn (the Sony transistors have a metal tab), and you will see that colour 'smear' on the screen - easier than looking the manual out

while possibly dangerous, but apparently safe with Sonys, was the single best advice you gave, i.e., no need to swap driver transistors (B and G obviously working), just locate the one which changes nothing, and replace it.

Save a little bit of effort.

 

[Nigel Goodwin]

Well, in point of fact, no.

But every color CRT has (had) RGB guns and something to drive them.

Not of any relevance to the discussion at point - but that statement is entirely incorrect

Sony Trinitron tubes have a single gun!

Not having repaired a Sony, in particular, doen't disqualify the advice.

It does, in that (as I've said repeatedly) his exact description was a VERY common fault on Sony CRT sets of a certain period.

This diagnostic:

while possibly dangerous, but apparently safe with Sonys, was the single best advice you gave, i.e., no need to swap driver transistors (B and G obviously working), just locate the one which changes nothing, and replace it.

You've not been paying attention have you? - assuming it's the usual extremely common fault on Sony's, then all three are working - but one transistor is slightly leaky and not working as well as the others. From his description it sounded more like the green transistor was faulty, so I don't know where you got the idea the B and G would be OK?.

Touching the collectors is safe in an earth free environment - but as in all cases don't put your other hand on the chassis

It's good practice to keep one hand in your pocket.

 

[cowboybob]

Not of any relevance to the discussion at point - but that statement is entirely incorrect

Sony Trinitron tubes have a single gun!

View attachment 67660

Looks like three to me. All in one gun assembly, to be sure, but three individually driven cathodes, or what I would refer to as the "color guns" within the entire gun assembly.

Nigel, I bow to your expertise on this, but I maintain (although, it could be a different gun that is at fault) the efficacy of the advice.

As an after thought, did you ever see a problem with the focusing barrel electronics causing the OPs description of the problem? Sony's method of beam transmission control and convergence spread was unique (and patented) but it did have focusing problems (sometimes refered to by Sony as "shadowing", the descriptive that the OP used).

 

[Nigel Goodwin]

View attachment 67660

Looks like three to me. All in one gun assembly, to be sure, but three individually driven cathodes, or what I would refer to as the "color guns" within the entire gun assembly.

Single gun, three cathodes - still not three 'guns'

Nigel, I bow to your expertise on this, but I maintain (although, it could be a different gun that is at fault) the efficacy of the advice.

I fail to see your point?, I'm a service engineer for a Sony main dealer - I've pointed out the almost certain fault with the TV (based on repairing thousands of Sony TV's) - but you seem to think generic advice on non-Sony TV's is more accurate?.

As an after thought, did you ever see a problem with the focusing barrel electronics causing the OPs description of the problem? Sony's method of beam transmission control and convergence spread was unique (and patented) but it did have focusing problems (sometimes refered to by Sony as "shadowing", the descriptive that the OP used).

No I've never seen or heard of, any such problems - his description perfectly fitted the description of a leaky green output transistor - as I've repeatedly said, this was a VERY, VERY common problem, and unique to Sony TV's. Another very unique problem is the purity changing - the scan coils are clamped on the CRT neck over a piece of sticky tape, and the tape slides backwards moving the scan coil position ruining the purity. All other TV's of course had long since used 'precision in line' tubes so didn't have any such problem.