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Pioneed SX-950

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Daves92gt

New Member
Pioneer SX-950

Hello everyone, I'm new here and kind of new to vintage audio. I just picked up a Pioneed SX-950 for free however it keeps blowing the main fuse at power up. I'm good with electronics repair but I'm new to fixing vintage audio. I've read that the diodes in the power supply tend to short out and cause the fuse to blow. Does this sound like a possibility to anyone? If so can you replace just the diodes or do you have to replace the whole power supply? I've heard this is a decent receiver and I figure for free it's worth fixing. I won't get to look at it till the weekend so I'm trying to get a couple ideas to keep me occupied till then. Thanks.
 
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Hi and welcome! Do you own a voltmeter? You can check the diodes in the power supply with a simple voltmeter. If the diodes are good, before you stick any more fuses in it, check the output transistors. With the meter set to ohms (1K),check resistance between the BASE and EMITTER. They will check like a diode in one position, switch the probes around and they should have no reading at all (if they are good). If you get a reading either way, they are bad (shorted) and there is your problem. If you find a bad output transistor or two, be sure to check for bad driver transistors also. Sometimes a shorted power transistor will back up to one of those. Sorry I don't own or have access to schematics, but one member here does have a lot of them. I beleive his name is Tom Bavis and he may read this thread and reply. This will give you a good start. Lots of luck!
 
Thanks for the reply. It definitely gives me a place to start. I was actually able to find a schematic for this unit off of a sticky on one of the boards on here. Wheres a good place to get replacement transistors if needed? Would I be able to get them at a place like Radioshack or do you guys recommend a place online. Thanks.
 
Probably online somewhere. I am from Seattle and my favorite place is a place called supertronix in Tukwilla. I personally have not ordered online, but from what I've seen here, a lot of people will probably chime in and let you know! Good luck!
 
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