How do you check the tubes

If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/
Convergence adjustment procedure to projection televisions are given in detail.

Check the collector voltage of blue output transistor at its video output board, which can be located directly plugged onto the neck of the picture tube. Check for any loose solder terminals at this board.

Hello, Sounds like an LVDS Cable or T-con Board.
Usually this will slowly get worse until it is repaired. It is caused by a failing T-con (Control) Board or connecting cable. T-Con Will Need replacement. This picture show's more extreme T-con board failures

I presume this is a TV with a picture tube, and if so, it would either be the chroma decoder IC or the jungle IC which could be possible causes of untrue colour, as well as the small components around them. Electrolytic capacitors, especially those in the chroma decoder circuit, tend to change value over time. Check and replace these first before diving in and replacing ICs. If the greyscale tracking is OK, as well as the overall picture, then the tube is probably OK. If it is not, and the images appear washed out and blurry, then the tube is on its way out, which means only one thing: throw it away.

With any IC replacement, it is a good idea to invest in special IC sockets - these are available from most electronics stores for a small price (you then trim and solder the sockets to fit the board as required) this will make it easier to swap ICs in the future if necessary without further soldering.

Hello
If you see the picture in yellow colour, means that there is no blue colour output from the video drive section in your tv, Yello is the mixtrure colour of red and green. Green is actualy there. blue colour is absent.
To detect this fault, you must open your tv. Just look in to the video output section, can be located at the picture tube base card, which is plughed into it diretly. See for any loose soldering points there. Check whether transisotors are used for red, green and blue output stages, or an Ic or three seperate Ics are used for this purpose. Anyway, blue catode of your picture tube pin gets a hig voltage, and so the blue emission is absent. You just check the voltages at red,gree and blue catodes, at the respective picture tube pins, which can be taken at picture tube base card. All of these three pin voltages must be somewhat equal to each other. In your case, no voltage at blue cathode will be higher that the other two. Check for the reason. It may be due to an open video output transistor [blue], or an Ic, of one Ic if used for the three colour outputs. Check and replace the same, will rectify your problem. Ok
If you have andy difficulty, get it to me through Fixya. Ok
Gopakumar, India.

Check fuses on power/delection board. Besides normal looking fuses there are micro fuses that are small and are yellow or blue in colour

You may want to recheck your connections coming off the blue tube to the board. Also check the IC links/Pico fuses on the power board. I have a repair manual for this Tv if you need it. [email protected]

you will need to change out the convergence board if the blue and green wont align its time for a new board

This is not a user serviceable problem. Apparently the red and blue screen colour tubes/guns are inactive. Possible open green screen control. Also, if CRT type, the tube may be failing

this an indication that one of the tubes may be out. red or green