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K150 pa amp blowing fuses [message #12471] Tue, 08 December 2009 22:36 Go to next message
jessadr is currently offline  jessadr
Messages: 15
Registered: November 2009
Location: Murfreesboro, Tn
Junior Member
Just got a k150 pa that is blowing 3 amp fuses.. seems one of the 400ohm resistors is open. Have 200ohm on the others. 1 of the 400ohms is ok. A wire was off of the power switch lamp and had shorted to the case must have blown resistor.
Lite bulb limit tester is bright all the time. Can I replace the 400ohm with a standard sand 10% resistor, or do I need a flame proof 5% Or does it only limit voltage to the lamp and not needed.
Slow blow 3 amp fuse with test light bypassed turns red and blows in just a few seconds. Transformer hums.
Both Caps valves are not open or bubbled. No dc on the caps with the light bulb ? bridge diode also may be blown. Never let any smoke out while testing. Wanted to ask the best guys before I start pulling parts out.

thanks
Jess

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Re: K150 pa amp blowing fuses [message #12472 is a reply to message #12471] Wed, 09 December 2009 05:56 Go to previous message
stevem is currently offline  stevem
Messages: 4772
Registered: June 2004
Location: NY
Senior Member
To the right of those resistors as youface the front of the amp is a black block with 4 wire terminals
2 black yellow wires.
one green and one red.
This item is called a bridge rectifier.
Unhook the red and green wire, install a 2 amp or less fuse and if that fuse still blows then that bridge rectifier is shorted.
If it does not blow than more than likly the amp ha at least one blown output transistor, and on the 5033 driver board a blown driver transistor and a open .47 ohm 1% 5 watt resisitor.
Let us know what you find.

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