Why does my sony trinitron makes a high pitch noise when on and/or off ?

More expensive to fix than replace. Throw it out. If you're interested it's probably a bad capacitor.

Four blinks - No vertical Deflection (V STOP), Screen goes to a single horizontal line then the video signal muted. Check for any loose sodering points at the vertical output section.

Hello
The problem is with its backlight inverter board. there are some step-up transformeres [small ones] fitted on board. If any one's core bacome loose this fault will occur. Just open the TV and listen to which one makes hi-pitch noise. Replace it, if you can buy it from the electronic market at your town. In most cases, the inverter board needs replacement.
This board can locate on the right or left side of the panel, fitted vertically.
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There is some hard ware problem for this physical site visit required.

Many Sony sets use a stereo processing integrated circuit (IC) that causes this problem when it goes bad. The part is an SBX-1637-11 and is available from several parts suppliers. One I use a lot is MCM, and their page for this part is here.

Changing the IC is not difficult if you have some experience working with soldering electronic parts. If you're not comfortable with the idea of doing this yourself, a TV shop could do the repair and the cost would be much less than a new set. It would definitely be worth repairing if the picture still looks good to you.

Shut it off and unplug. You have a serious HIGH VOLTAGE problem that could cause a fire. Professional repair needed.

this most likely a coil or transformer that is doing this
And yes this is worth fixing , shouldn't be to bad on the cost of the repair

This unit needs a tuner. A new one from Sony will run over $70, so I doubt that it is worth it. It is possible that poor ground connections could cause something like this, but the symptoms seem a bit too severe. I think it is time to invest in a newer set.

Dan

Turn off tv and check all connections and unplug it from power supply. make sure that everything is connected tightly on the back of tv( cables and stuff) turn it back on, if you see a red flashing light or red solid light, chances are there might be a problem on the capacitor or wirings inside it.

The high pitch squeal you hear is usually caused by a coil vibrating, normally in the horizontal circuit. I've also seen the ferrite bead on the horizontal output transistor do this, but, it is rare. I normally will repair this by finding the coil and "tightening" it. To tighten a coil, technicians use different chemicals, such as, a hot glue gun, rubber silicone or even finger nail polish. I will find the coil that screams by starting with the usual suspects and using a wooden dowel, barely touch the coil and if the pitch of the noise changes, then, thats the coil that needs repaired. If you do not know your way around the inside of a television, I never recommend you do so, since, this procedure must be done with the set turned on and you poke your hands around the inside of the set by the high voltage circuit. Hope this helps your decision.