hello i got a lincoln that kees blowing the protection diode for some reason checked leads and normal stuff all ok .
anyone know why it would do this , and got an idea on where to start looking for the problem.
cheers.
president lincoln help
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webheadx1
- Regular
- Posts: 18
- Joined: 06 Jun 2010, 14:17
Re: president lincoln help
ok found out that the final trani was put on wrong ,and she black and the little board that gets attached to it, does anyone know what that little board is that gets attached to final trani as it looks popped dont know if it is but i would like to replace it just incase same time i change the trani.
but with this out radio works as it should apart from tx lol , wicked now to find out what that part is if anyone can help .
ohh sorry for double post can someone delete the other 1 cheers.
but with this out radio works as it should apart from tx lol , wicked now to find out what that part is if anyone can help .
ohh sorry for double post can someone delete the other 1 cheers.
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zephyr
- Radio Addict
- Posts: 743
- Joined: 01 Nov 2007, 15:31
Re: president lincoln help
If I understand your post correct, you say that the final transistor has been fitted in the wrong way.
Can you explain how with a little more detail, that way we might be able help you out.
When a final or driver goes short circuit it normally blows the fuse not the protection diode as it can draw a high amount of current.
The components fitted onto the final and driver are diodes used as a thermal devices to reduce the input to the base of the transistors by shunting a small amount to ground when the transistors get over heated.
They can be replaced with IN4148 diodes but don't use IN4001's thinking you'll bullet proof them, if it manage to draw 1Amp it would destroy the skeleton pre-set VR for adjusting the biasing, leaving you with no drive to the base of the transistor and thinking you need a replacement final.
Can you explain how with a little more detail, that way we might be able help you out.
When a final or driver goes short circuit it normally blows the fuse not the protection diode as it can draw a high amount of current.
The components fitted onto the final and driver are diodes used as a thermal devices to reduce the input to the base of the transistors by shunting a small amount to ground when the transistors get over heated.
They can be replaced with IN4148 diodes but don't use IN4001's thinking you'll bullet proof them, if it manage to draw 1Amp it would destroy the skeleton pre-set VR for adjusting the biasing, leaving you with no drive to the base of the transistor and thinking you need a replacement final.