GM300 face buttons non operational

[Batman]

can read / write to radio, but front buttons do not work at all.

radio powers on mon. light is lit and radio shows ch1.

can't change channels, scan or anything.

but again can read / write to radio alter modes etc. w/ no problem.

[Bill_G]

Got a spare whole front panel to swap on to the radio? I'd tear it down and check for Pepsi syndrome under the buttons. Scrub it and the buttons in soap and water careful not to remove the conductive tips on the buttons. Maybe some broken wires.

[Batman]

tried cleaning the buttons to no avail they still do not work.

[Bill_G]

If not broken wires were evident, then you need to A-B the front panel with a known good one to determine if it's a logic board problem, or simply the button and display panel gone bad.

[Batman]

would the radio still read / write using rss with a bad logic board?

[jackhackett]

You can check to see if it's the buttons or not by checking some of the pins on the connector that the control head plugs into.

The display board connects through P9/J9, the smaller of the two plugs (12 pins). You should see pins 1 through 7, then it skips pin 8, then 9 to 12.

Pins 3,4,5,6,7 are for the buttons, 12 is ground. You can try measuring the voltage on them while pushing the buttons, it should drop from around 5v to near 0v. The pins are pulled up to 5v through 10k resistors and the buttons pull them to ground, so grounding those pins should simulate button presses and tell you if it's the radio or the buttons causing the problem.