Colour Problems on a 1980s or 90s NEC

Hey,

I recently inherited an old NEC TV from the 1980's or 90's, from my late grandfather and the colour on it is really messed up. There is no red. The other colours seem to work fine, but everything red just shows up grey. Normally i would just pitch the tv, but it has sentimental value and i think it would be nice to fix it up and make it run really really well. Perhaps keep it running till i can give it to my future grandson . Yesterday as i was watching it the red suddenly came back for about 5 seconds, so i assume it can be fixed.

I came to ask you guys agian, because last time i had a tv problem you guys were so quick and nice about it. I hope you can help. There are tint, colour and autocolour controls on the front, but none increase red. I can get the model # if necessary. Is there just likely a loose wire? or controls that i would have to take off the back of the TV to fix it? If someone could give me a walkthrough or a link it would be awesome.

Thanks alot,
Scott

[dr.ido]

When there is no red does the picture have a blue/green look? If so, the red gun isn't working. If you can make the red come on go by whacking the back of the set (not hard enough to break anything) there is probably a dry joint on the neck board (the board connected to the back of the CRT).

Take the back off the set and look at the solder side of the neck board. If any of the joints look cracked or burnt they need to be resoldered. Usually, it will be the driver transistor or cathode resistor.

Ok. So i smack the back of the set... and if that doesnt work... i take off the back and solder anything that looks cracked up and thats it?

[dr.ido]

Smacking it is a way to diagnose the problem. If the red comes back or flickers when you smack it then there's almost a 100% chance you have a dry joint. Then it's time to go looking for any suspicious joints and resoldering them.

Dry joints look something like this:



If you've never done any electronic soldering before it is a good idea to practice on a scrap board first to get a feel for it.

If you've never done any electronic work at all it may be a better idea to get someone else to do it for you. The high voltages present in a TV can kill you if you touch the wrong thing and some parts will retain a charge even when the set is off and unplugged.