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[SOLVED] Info needed on a transistor

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lost bandit63

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Have a burnt transistor can only make out these numbers ST 99235 mje 55t the two numbers in front of 55t are missing it could be 2955t or 3055t [ 2955t is a PNP and the 3055 is a NPN] so how can i tell which type this amplifier would take without any type of blue prints.This is a old unit made in the late 70s .pentetrator 200.Thanks .P.S transistor is shorted out cant take any reading of of it.
 

KlausST

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Hi,

Maybe you can take a picture from the pcb. Top and bottom, so we can see where the thre transistor connection go to.
Maybe you can add informations like voltage or load...if you have.

Klaus
 

betwixt

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In most amplifiers there will be two output transistors and if it's stereo they will be replicated in the other channel. Can you match the numbers you can see with the other ones?

If that isn't possible, with the failed transistor removed, power it up and measure the voltage between the collector and emitter connections, if the collector is more positive it will be NPN (MJE3055) otherwise it will be PNP (MJE2955). It would be wise to replace both output transistors, if one is shorted, the chances are the other has been overstressed. Those types are not expensive.

Brian.
 
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