I want to know if i wil c5888 transistor to replace c5885 transistor in a sony 21 inch colour tv or which transistor wil i use as a replacement?

The LOT is faulty that's why the Horizontal Driver transistor goes faulty even after changing it. You have change the LOT Line output Transformer along with one more now c5885.
If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience.
http://electro-medical.blogspot.com/

BU208 Can be substituted.

First, You should to replace by original part, then you should check the voltages on power supply, and check the voltage for vertical IC based on datasheet, also check the voltages on vertical section including yoke and last you should check the ESR capacitors on vertical section.

I would check cable connections, and the cable itself, try replacing the cable.

Check the video output stage circuit. Check the video output transistors. These transistors can be located at the video output card, at the neck of the picture tube, will directly plugged on to it. If the red output transistor is open, this kind of fault can occur. Replace it and check. To get some details, http://electronicshelponline.blogspot.com/ Pull up older posts.

• Power Supply B+ is higher than normal


• Partially shorted Flyback Transformer


• Bad Deflection Yoke


• Too much oscillation on the Jungle IC


• Bad capacitors around the horizontal output transistor

You have to check the high voltage diodes near the horizontal transistor and the small transformer. Diodes might have gone leaky. Check the capacitors also.Replace the black colored diodes with new ones with identical part no.

Rarely EHT coil will have problem.

check the relay drive transistor
you need a qualified tv repair personal to check tv

oh an easy one LOL That part # is 1-453-268-21 and available at http://www.partstore.com at a price of $82.12. One thing though Make sure you check the horizontal output transistor with all the leads disconnected from the curcuit as this part sometimes goes bad when the fly does. My regular practice with any flyback replacement is to automaticly replace the HOT(horiz. output transistor) as well as resoldering the hhorizontal driver transformer and the horiz. driver transistor. Hope this assist yout repair and makes a happy one. Thats what were here for! Good Luck.