TV colour has turned pink!

[Mark]

Does this sound terminal? My parents have a 6 yr old Sony 25 inch standard TV. It's used every day but over the last few months started to take a few minutes to come on each day. It went ok for a few weeks but recently started again to take a while to come on, but now the picture has also gone pink! It seems to be only white or light colours that have turned pink. For e.g, sky & cloud shots and anything that supposed to be white are all pink (watching Emmerdale all the sheep were pink, lol) Darker colours appear to remain normal. Could it be the tube on the way out?

[mrcheerful]

could be, but the first thing a pro would do is give the set a good whack with the flat of the hand on the casing , if this affects the picture/fixes it then probably you have a bad connection inside, in which case cautious wiggling of boards inside using a wooden rod might locate the fault, otherwise it needs a pro to look, but for a tv of that age it is probably not worth getting a repair place to look at it.

mrcheerful

[The Natural Philosopher]

Green gun is fading or its drivers are shagged. Should not be shagged after 6 years. Usually do more like 10-15.

Its probably fixable, but price may exceed what you are willing to pay.

If you have a local repair shop of some credibility, take it in. Often they will p/ex on on a recon unit which gives them time to fiddle with yours and fix it if they can.

[Andy Hall]

I understand that failure of the green is a fairly common fault with Sony tubes :-(

Comes from watching too much Emmerdale..... :-)

This would result in a magenta to pink caste on the picture.

.andy

To email, substitute .nospam with .gl

[Farmer Giles]

picture/fixes

You must have met some strange 'pros'.

in which case cautious

Frightening advice.

This is probably a tube fault - green gun low, or no, emission ( assuming 'pink' is a magenta raster). There are quick ways of determining this - swapping drive leads over, for example - but not advisable for the inexperienced.

[Christian McArdle]

Well, we were taught the finer points of "percussive maintenance" on my BEng degree course.

Christian.

[Dave Plowman (News)]

No - it's usually the red that ages in old trinitrons requiring the green drive to be reduced - many old Sonys had an external control to allow this easily.

[Dave Plowman (News)]

Foregrounds going slightly pink should respond to a grey scale line up. Assuming it's possible on such a set. You might have to get into the engineering menu. Older sets had pots to allow this - not sure about yours, which is probably software controlled.

The tube could well have years left in it.

[Dave Plowman (News)]

Unless it suddenly happened, it's unlikely to be a dry joint, etc. Ageing of the guns at different rates happens on all tubes, as the gains are different. Many simply put up with this - or don't even notice. But all sets must be adjustable somehow, although IIRC may do an auto grey scale balance.

[Martin Warby]

my physics teacher gave me the advice 'if in doubt give it a clout' sometimes it works sometimes it don't

Martin Warby

[Mark]

Thanks for the replies. I'm not sure if there is an engineers menu but if any one knows. The model is: Sony Trinitron, KV- 25F1U.

[tony sayer]

In article , Andy Hall writes

Never been that impressed with Sony TV always look too red even when new. Very poor performance developing this sort of fault after 5 years:(

[Farmer Giles]

Judicious tapping is an essential part of TV fault finding, but giving the set 'a good whack with the flat of the hand on the casing' is not the recommended method!

[Ian Stirling]

Luckily, most doctors (other than obstetricians) don't get this sort of training.

[mrcheerful]

this place have a chassis for one at 20 quid:

[mrcheerful]

found this might help KV25F3U SERVICE MODE PRESS ON SCREEN DISPLAY, DIGIT 5, VOL. + AND power

[Dave Stanton]

First thing I do when a piece of equipment comes in for repair and I have been doing it for 22 years.

Dave

[N. Thornton]

Either green emission going down, or possibly just needs gren drive adjusting. Falling emission is an elementary fault to fix - or to put it more correctly, postpone for several more years - but strangely few repair techs know how to fix it. Send it to me :)

The solution is to up the tube heater voltage. If the heater is fed from a LOPTF winding, add another turn round the LOPTF and wire it in series with LOPTF output to get more V. If its fed from a regulated supply, feeding it from before the regulator usually works when the reg is linear. With SMPSUs just look around, you can usually find a suitable V somewhere.

Or those are all non options, add a small mains TF to run the heater.

There are other ways to boost tubes, but dont use the popular zap-it approach if you want it to last long. Though they do boost tubes, the tubes then lose emission relatively rapidly, and as it goes down they smear badly, ie it boosts them for a bit, but makes them unrepairable longer term.

Boost V: 30% typically gives excellant results, I've used upto 70% on an experimental only basis - and it worked. Cant recommend 70% cos its not risk free!

NT

[Dave Liquorice]

So why are three good blows (top and both sides) from a mallet part of the final testing on Panasonic production lines? This is after they have been pushed, tube first, off the conveyor onto the a padded mount at about 45 degrees. This is with the set powered up and a mirror positioned so that the mallet wanger can see the screen...

Domestic TVs are tough old things. Dropped a 15" colour onto the top of some shallow concrete steps which it the proceeded to slither down for 20'. Picked it up, carried it back up, powered up and part from a few scratches on the case you wouldn't know.

[mrcheerful]

Thank you for the confirmation, Dave.

Incidentally I used my neighbours, thrown out TV with the same sort of fault, for about 6 years, initially my friend the tv man came round and I asked if he would have a look as it was a bigger tv than I was using, he said "I know what's wrong with that" and slapped it hard, perfect picture instantly, a few months went by and the picture dropped a colour again, I wiggled the boards around till I found the one that cured it and I wedged a stick in to keep it working. Several years later it lost the picture completely and I threw it out.

mrcheerful