OpenGD77

In theory it would be possible to have flat audio option for the radio, at least as far as the actual RF chip is concerned. However there is no control over the additional audio components in the microphone and speaker paths. So the end result may not have a flat response, especially at the low freq...

Making a recording probably wouldn't help. The tones won't be recorded. It is not unusual for CTCSS to sometimes be affected by individual voices. The transmitting radio should filter out any low frequencies in the voice before adding the CTCSS tone and likewise the receiving radio should filter out...

Your description indicates that you are accessing the repeater OK but the content of your transmission is not being accepted. You have checked the talkgroup settings, timeslot and colour code, that only really leaves your user ID. Have you entered it correctly? Some Repeaters will only pass traffic ...

From your description it sounds like you are accessing the repeater OK but possibly with the wrong Talkgroup set. Or maybe you have programmed a private call instead of a group call. I would check your talkgroup programming.

I think you have Latitude and Longitude confused.
Latitude can't be more than +- 90 degrees.

That looks like what we refer to as the V5 board.

Your main problem may be internal PCB damage. The PCB is an 8 layer board with the 12V supply running on one of the internal layers. The place you can see the burning is where the internal layer links to the bottom layer. If it has got hot enough to damage the insulation between layers then it might...

The burnt area in your picture is not a component, it is a PCB track. This track links the 12V Battery supply (on internal PCB layer 4) to the 'always on' 4V regulator that in turn supplies the 3V3 for the main processor. As this is a multi layer board you may have some internal damage which would b...

There is no keyboard reset.

The password bypass method is common to all TYT manufactured radios. The RT 90 is made by TYT.

Colin G4EML

They are holes! Because this is a schematic from a PCB design program you have to define everything that is connected together. The mounting holes have to be connected to ground. This is also a very early schematic for V2 radios. It will not be correct for later versions. However it is the only one ...