Motorola GM300 Not powering up

[Tetra40]

Hello everybody,
Have a big problem, 2 days ago i was playing with my GM300 16PIN back connector and i think i shorted something so i was trying to connect my GM300 to pc to work as FreeRadioNetwork link, so i made cables connected RX and i was ok, then i was connecting TX and after that i tested it in Test room. I transmitted on portable and my GM300 RX light was flashing very fast, and i wasn't able to transmit from it. So i turned my power supply off to not shortcut something disconnected every cables and turned it on (my power supply has a protection so if connect the power wrong like plus to minus or minus to plus it will not power up, will just flash showing me that's i connected the power wrong) it powered on normally but the radio not. So i want to ask for a help

Information:
When i turn the power on my radio not doing anything (like flashing lights for 1second etc.)
When i connect the power to Pin10 (Ignition Control) Nothing happens
The radio is VHF, 25W, 16Channel, TANAPA: HUD3404A, MODEL: M33GMC29C2AA
Thanks!

[Will]

Check the Pico Fuse near the accy connector on the logic board. It is probably open.

[Tetra40]

Thanks, but if i find it how can i close it?

[jmr061]

An open fuse means your blew the fuse. You have to replace it. Those are pico fuses. Little small green things. You could solder a blade fuse holder to each end of the pico fuse and put a 3 amp blade fuse in it. Been there done that in a pinch.

Jason

[AEC]

Most of the Pico fuses are 4 Amps.

Never replace with a lower, and certainly never, with a higher current fuse. These ratings are for circuit protection, they are supposed to blow long before any component damage occurs.

Replacing with a lower current rating can cause the fuse to blow on a minor surge in current demand, such as is often occurring with equipment being turned on.

[Bigred]

If the pico fuse was blown (or missing) the radio would still power up by applying 12V to pin 10, which sounds like the OP has already tried.
Looking like it's more serious than that. Maybe opened a trace?

[guy being a guy]

Look at the small white 5 pin connector on the logic board.
The red wire is the 12 volt comming in from the main connector on the PA. Should be 12volt. If not,remove PA - I have seen the reverse polarity diode get hot and unsolder itself.
Got 12 volts on that red wire ? Make sure then you have it on both sides of that small green fuse.
I have seen the actual runner burn up and become an open. Do a continuity check from the red wire to the fuse and check for an open runner.
Notice the 3 IC's that are screwed to the chassis. The large multi pin one is your audio amp. The other 2 are a 5volt regulator and the other is a 9.6 regulator - they are pretty tough only seen one bad in my 26 years.
Next is the check if 12 volts is making it to the volume on/off switch. Take off control head and measure.

Note : you can apply 12volt to the ignition sense ALL day long. If the accessory connector is (or never has been) programmed for ignition sense it does NOT matter. If it IS programmed for ignition sense then you MUST have it for the radio to power up.

I bet you blew the fuse or opened the runner to it. I have "in a pinch" taken a SINGLE strand of the SMALLEST wire I can find and soldered across the fuse

[guy being a guy]

I bet messing around , pluging in and out of that rear 16 pin connector ,you BENT a pin or two. Straighten them out with a pair hemostats and be careful as I do it all the time.
When you do that it causes the runner to open

[Tetra40]

Yes, yes thanks i fixed it yesterday.