How do i tune in stations in the RM 870 sony trinitron

get a SONY universal remote number RM-U302 it needs no codes just press the SONY item say in your case TV and the remote will self calibrate to your type

How can i tune chanells. How can i open the menu for tuning with RM-841

Check this link for details.

flashing led indicates trouble codes,you must have a sony service manual to interpret the codes

try at E-bay.search " Sony XXXXXXX( TV model number) compatible Remote"otherwise search over the google then you could get the Remote model number .it might be RM-XXXX. If you don't have PIP (Picture in Picture) RM-869 can be used

You can get the manual and codes on the link below.

http://www.oneforall.com/uploads/support/2c295be6404e14dc9fcedf25f0195bb8.pdf

You need to have remote control to perform tuning for radio because unit has no control buttons to do so.
You can get remote from Sony Accessories. Please write model number DAV-S300 in search box to get result.
Remote details are as under...
141883811 RM-SS300 REMOTE CONTROL Approx $70

WELL I need some more information so I be able to assist you, first , it could be that the REMOTE CONTROL is not that came with the TV originally , and since all SONY remote control have the same basic codes ,it could be that the remote doesnt have this specific feature. I did some research base on the model of this TV , the original remote control model num. is RM-Y127 and
not RM-Y153 , maybe thats why it doesnt have the PIP feature. hope this info been helpful

dfi

I have KV-X2982U, With the television on 4, Grip the top side of remote control RM-833 and reverse it, putting it back in the holder. Press Menu on the remote. Several options appear. Press the white button "Preset". You can then manually tune in the setting to channel 4 by pressing the green button, or alternatively you could tune in all channels automatically by pressing red. You may get a better signal on the other channels this way. Good Luck.