Galaxy DX959 Out Problem-Final Blows??

[nukem]

I need some technical advise.
I have a Galaxy DX 959 that lost output.
The final blew without reason.

I replaced the final and with power on the final smoked and got very hot.

What and where should I looking for as the problem here?

Thanks,
Nukem

 

[bushwacker]

I need some technical advise.
I have a Galaxy DX 959 that lost output.
The final blew without reason.

I replaced the final and with power on the final smoked and got very hot.

What and where should I looking for as the problem here?

Thanks,
Nukem

if it smoked when you first turned on the power...or got very hot.....look for a dead short. The only thing that will make that transistor get hot when the radio is not keyed is if current is going through it.
make sure the tab is insuled...make sure the insulator is on the screw that holds the tab to heatsink.

if the final is heating up the problem has to be in that area.
You should always monitor the current draw of th radio when your doing work on it. After replacing any parts and powering up...you should watch the current draw... if you see the radio drawing lots of current...you have a bad short and you should power down immediatly.
The average radio will draw under .5 amps in rx mode.....if the radio draws more there is something getting hot.

Check that mounting tab on the transistor and make sure its insulated.
There has t be a short to ground if its heating up without keying the radio.

Thats about all I can tell you without more input

 

[9C1Driver]

I sure hope those are cheap mosfets and not 25 dollar 1969's.