Question about Carver PM950 Amplifier
I have an amplifier marantz PM-34. this amplifier work very well for about 12 years. but sudenlly two days ago, when it works, it turned off. after that i check it and i found its fude broken. i bougth a fuse with that characteristics. but after installing new fuse, the amplifier smelled, in the main circuit, there is a triple based component, which i guss it is a resistante, because it named R23 and on its body printed R0.18ohm. this component is dual (i think one for left and other for right). please help me that is the problem is due to this component or maybe some other component has problem. I see precisely other component, but there is no visual defect. unfirtunately in my countrey, there are no marantz agency that i cen refer.
The part that you speak of is called the emitter stabilizer resistor. It is common to the output pair on one channel. You will find that the large "output" transistors mounted to the heat sink either side of this resistor will most probably be faulty.
Best not to run the amp at all whilst in this condition.
To be sure that you have an effective repair, you will need to change both these parts, and also the "driver" transistors that connect to the outputs. They too are in symmetrical positions close to the the output transistors. You should also check that the 3 legged resistor you mentioned is measuring its correct value, and check all other low value resistors in the output stage area to that channel.
If you are not familiar with repairing this sort of equipment, perhaps you can find a repair guy with some experience on audio equipment, then this work should be all he needs to do to repair the amp. I would also ask him to "blanket resolder" the output/bias stages and power regulator stages in the amp as problems with heat stressed cracked/failed soldering and dry joints often cause these amps to blow the output transistors.
BE SURE THAT THE CORRECT PARTS ONLY are used for the repairs. Different transistors could cause future problems with the amp. The parts can be obtained relatively easily from a marantz distributor(we can find one in a country near to you). OR if you can give me the markings to each of the parts you need, I can provide you with an international source to get them from.
The amp is decent HiFi, and worth repair. Happy to provide you any assitance I can, Good Luck
Posted on Nov 03, 2008
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