How can i delete the talkback on a galaxy 73v ?

Samsung Galaxy S3: Talkback Mode On: Can't enter password:

If you have a password on your device then you will need to double tap on the screen to gain access to the lock pattern or code that you have on your device. While in Talkback mode you will need to double tap any selection in order to fully make that selection.

You need to double tap on the screen pause for a second then swipe your screen In order to gain access to your device. You cannot double tap quickly then go to the process of swiping to open our device

Reference Link:
Disable Talk Back Mode in Samsung Galaxy S3

Unlock Phone in Password Mode:

If you have chosen the Password Unlock mode on your phone and are unable to enter the password due to the Talkback mode, do as follows. First of all long press the password field and then double tap it. Now you will see the keyboard. Long press the alphabets/numbers of your set password and when you have typed it, long press/double tap the "Done" button on the keyboard. You can now follow the two finger swipe and double tap as described above to deactivate the Talkback mode.

Reference Link:
How to Disable Talkback on Android Devices

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it can be done but it is a long process . check out www.cbtricks.com they have the information you need about talk back . if what they have isn't what you want you may have to google it for the information you want.

Here is a link to a channel chart and band switch setting.
Galaxy Radios DX73V Service Manual

turn the talkback knob to the right and push it in to engage talkback.when you get the volume you want leave it alone .Now key the mic.You will probably hear a squeal coming from the speaker.Now turn the volume down on the talkback knob until the squeal goes away.If you run your RF gain wide open it may squeal also.

adjust your talkback to just open then set your echo to where you want it. Now turn your amp on and re-adjust both the talkback and the echo . If you have a speaker nearby the radio may be feeding back through it so move it away from your radio . Now start talking with the mic and adjust your echo because you should be able to hear yourself talk through your talkback.

common problem bad solder joints in the vco circuit take it to a PROFESSIONAL

Do you have receive?

Check out the speaker.

timspur, hi. First off, using the talkback with a tuned Galaxy will give you problems, so you need to use a good noise cancelling mic like a RK 56, or Astatic 636. If your running an amp, that will only amplify the problem. Here is a mod if your comfortable working on your radio, to tone down the TB volume.
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Talkback can become distorted if these radios have been "peaked," and there is no cure because the talkback just amplifies what goes to the RF section. Try adding a 470k ohm resistor from junction of C155/R207 to the junction of C187/R235 on the solder side of the board. This will also give you clean talkback on SSB and FM. Try different values of resistance to get the amount of volume you want. The less the resistance the louder the talkback will be.**
Hope this was what your looking for,, I know for a fact that the Astatic mics do help tone it down.
Let us know,,, Mechanic