OpenGD77

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 ...

To get 5W output you do need a fully charged battery or an external power supply and a very short good quality connecting cable. Roger, Power adjustment is well known for being difficult. It depends so much on the test cables, dummy load match and supply voltage that I doubt they have very tight tol...

Hi Roger,

Yes I did the SK1/SK2 reset on both radios.

Cheap RF devices probably vary greatly in performance between batches. They may even be using whatever transistor is cheapest at the time.

I think it is unlikely you will find a good compromise for the calibration in all radios.

Colin.

Hi Roger, Here are the readings from my two radios using the Marconi 2955. MDUV380 145MHz 103, 121, 162 1.16, 2.21, 5.40 73, 100, 118, 158 430MHz 79, 102, 154 1.51, 2.74, 5.80 44, 69, 89, 141 440MHz 81, 105, 153 1.49, 2.74, 5.60 42, 70, 92, 143 450MHz 84, 107, 156 1.53, 2.65, 5.70 43, 72, 95, 145 MD...

That depends on exactly what you mean by contacts.

The radio will hold 1024 contacts to be used for making calls, such as talkgroups and friends private IDs.

It can also hold the entire world database of DMR IDs, used to display the call sign and name for an incoming call.

Colin G4EML

Yes, there are often multiple options for what you are buying, sometimes under the misleading title of 'Colour'. You need to double check exactly what you are ordering. The default setting is often the cheapest item which may well be just an accessory and not the item you thought. The actual buying ...