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Old 24th Sep 2006, 11:37 pm   #1
ballistic
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Default Sony Trinitron - EW problem and flyback lines

Story so far...
I didn't see itworking until after I got it home after quite a bumpy ride in which the TV fell all the way over (quite a bump).

The picture has flyback lines (which I know exactly how to fix) but also the picture is squished inwards at the bottom edge (which I don't know how to fix).

Seller says it was fine at his end, and I think it probably was.

I'll start by turning down the G2 screen pot, as I'm very familiar with this from the other TV.

Now, any idea how to fix the squished screen effect that could have been caused by the bump?

I'm tempted to find out how to get it into service mode and adjust it there, but I'm sure that wouldn't be doing it right - and anyhow it never came with a remote and I don't know how to do that.

Any help appreciated as ever.
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Old 25th Sep 2006, 7:23 am   #2
Nickthedentist
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Default Re: Sony Trinitron no. 2

If it really was a bump that made it faulty, then I'd look for cracked print or soldered joints that have failed, particularly around heavy components like the LOPT.

Use a bright light, and even a torch.

The other thing I'd do is to bash the PCB with a screwdriver handle while the set's running, to see if the fault can be made to come and go.

Good luck,

Nick.
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Old 25th Sep 2006, 1:31 pm   #3
Sideband
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Default Re: Sony Trinitron no. 2

From past experience, Trintron tubes were very sensitive to bumps which could dislodge the shadowmask (or whatever Sony refer to it as). If this is the case then the tube is ! However I would have expected severe purity errors as well if this was the case.

Any chance of a screenshot so that we can see the distortion on the picture?


Rich.
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Old 25th Sep 2006, 3:33 pm   #4
Welsh Anorak
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Default Re: Sony Trinitron no. 2

Hi
Must warn you the tubes on the KV29XXX series are very short-lived and can cause flyback lines and muddy colours, eventually causing the set to trip off just before the picture appears as the CRT has failed its greyscale adjustment test.
If adjustment gives a very good picture, then:-
1. Heave a sigh of relief
2. Replace the 680k resistor by the G2 adjustment pot
3. Return the pot to optimum position (simple method: select text, turn to get flybacks, back off till whites flare then set it halfway between).

Re your funny shaped raster, I agree the best thing is to look in the E/W circuit for physical damage as there is rarely any need to touch the service adjustments - unless someone's been there before....

Glyn
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Old 25th Sep 2006, 5:54 pm   #5
Nickthedentist
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Default Re: Sony Trinitron no. 2

Quote:
Originally Posted by Welsh Anorak View Post
Must warn you the tubes on the KV29XXX series are very short-lived and can cause flyback lines and muddy colours, eventually causing the set to trip off just before the picture appears as the CRT has failed its greyscale adjustment test.
Yes

I bought one on eBay as non-working a couple of years ago, lugged it about 50 miles in the back of my little car, hurt my back carrying it into the house, then discovered the tube was ed. Exactly the symptoms that Glyn(?) describes. This surprised me at the time, as it was a newish model and I'd owned several other Sonys whose tubes were still as good as new even after 15-20 years of daily use. It had only cost me a tenner, but disposing of the "corpse" was hard work.

Nick.
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Old 2nd Oct 2006, 1:04 pm   #6
ballistic
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Default Re: Sony Trinitron no. 2

OK, I now have some photos...

First the bottom of the picture being squashed inwards...

http://www.btinternet.com/~ballistic...V/CIMG1496.JPG


And a close up of the flyback lines...

http://www.btinternet.com/~ballistic...V/CIMG1498.JPG


any thoughts?
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Old 2nd Oct 2006, 1:08 pm   #7
Welsh Anorak
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Default Re: Sony Trinitron no. 2

Hi there
Not sure which model this is! However, the flyback lines are your first concern because if the tube's duff the EW fault's a bit academic! The distortion seems fairly minimal so it might adjust out. If it's had a bash, first check none of the coils in the E/W correction circuit have cracked.
Good luck!
Glyn
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