Sony kv27fv300 changes channels by itself?

The Sony KV-36HS510 has an Auto Setup function for the channels.

1 Press POWER to turn on the TV.
2 Press TV FUNCTION on the remote control.
3 To continue running Auto Setup, press CH+. To exit Auto Setup,
press CH-.

Auto Setup automatically creates a list of receivable channels. When
finished, the lowest numbered channel is displayed.

To reset the TV to factory settings
1 Press POWER to turn on the TV.
2 Hold down RESET on the remote control.
3 Press TV POWER on the TV. (The TV will turn itself off, then back
on.)
4 Release RESET.

try to interrupt it by pushing the channel in the opposite direction or tapping the channel up/down button with your finger.

You have ONE of two possibilities....on the Front panel buttons, you MIGHT have a stuck button or leaky button....

I suspect that if ALL it does is change channels...it would be a channel UP or DOWN button stuck....yes, it can fire up the tv too....But it will dedicate itself to doing only ONE function.

IF you have multiple operations, like changing channels, menu appearing, volume changing....then the MOST likely problem is actually the microprocessor causing the problem....BUT it is STILL possible to have SEVERAL buttons stuck....rare, but possible.

And unfortunately unplugging it won't even help in any of these possibilities....

You have to start with pressing each and every button one at a time and see if the problem stops afterwards....

IF it doesn't, then the next step is to measure the resistance across each button....they should read Infinite ohms.

If any measure lower, the button should be removed and see if the TV acts normally...

IF the buttons are located on a separate board with a plug that can be disconnected, you can just disconnect that while it's acting up and see if the problem disappears.....

If it still misbehaves after this, you NEED to get it to a TV tech for further analysis with a scope.....

Try changing the channels on the VCR itself. If you can do that, then it would indicate a problem with the VCR's remote. If you are still unable to change channels on the VCR manually, it could indicate a circuitry problem, for which you will have to get the VCR serviced.

the problem is there is engaged button there..only technician can do the job by replacing the button that is always engage.

Two things may be at play here. The tv might be only programmed for reception on channel 2 and will need to be re programmed to receive other channels.
Also try some basic troubleshooting on the remotes. Start with the remote that came with the tv. Replace the batteries try the "MENU" button. If you can get into the menu try to "autoprogram" the TV

I think that is dried solder try to re solder the video chroma ic or change the capacitor 250v/10uf near the FBT (flyback)section

more info would be nice. If you're using optical, make sure its securely in both the tv and your vr-405 receiver. I have owned the vr-405 since 2000 and i just purchased a sony 32xbr6. HDMI into the TV, optical out to the receiver, it sounds amazing!

Defective tactil switch?? Remove tact switch control board.
unplug connector,use meter--check each switch.
If no problem found,leave unplugged overnight or longer.
Sony is famous for getting brain freeze!.........T.

Do you use the remote control or buttons on the tv itself? Many TVs have a child lock feature that will prevent operating the TV without the remote control. If you use the remote control you should be able to change chanels, and to disable the child lock from the menu.