| Author |
Message |
    
Jpm
| | Posted on Friday, July 11, 2003 - 8:53 am: | 
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Has dual finals, tricked out by eei. Sudenly started blowing fuses. I can't find any thing burnt or loose. Acts like a dead short, any ideas where to look. |
2600
| | Posted on Sunday, July 13, 2003 - 1:36 am: |
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Logically, a blown fuse dictates checking the parts of the radio that normally draw the most power. Statistically, they fail most often. That would be the finals, driver and modulator transistor.
There is a "test" jumper just in front of the finals and driver. Unless they soldered across it, pull the jumper and see if the fuse holds. If it does, that dual-final setup may have "hot-rodded" itself to a transistor breakdown or three. They usually don't look defective on the outside when they overheat and short internally. The modulator transistor may have gotten sideswiped by the overload if one or more, finals/driver have failed and shorted. Likewise, the bias diodes and bias trimpots should be checked before firing it up with a replacement final/driver. Could pop the new replacement if the bias circuit has been damaged.
73 |
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