Pioneer SX 950 internal phono amps not working.

kjack48230

Active Member
Hello all, was told to post here for this question. I got an SX 950 receiver that has bad phono stage amps, this has 2 phono inputs and neither of them work. Was told by a tech that the transistors on the board were bad and needed to be replaced. Anyone do this before and is there a schematic I can get my hands on? Any parts list I should be working off of? Any help would greatly be appreciated.
 
Service manual here. (wait for the link just below the manual picture to change from "processing" to "get manual". There is a lot of bloat ware there, so ignore the big download buttons.
There is also one in the AK database, but it is not as easy to read (but smaller in size) http://akdatabase.com/AKview/displayimage.php?album=44&pos=112
Any hum or noise at all? FWIW I would start with power supply. Check the +28 and -17 that go to the phono circuit. GL with it.
 
Do what John Stumpf said deoxidize all the switches push buttons and take a pipe cleaner spray some Deox on it and work it in the PHONO RCA jacks in the back there are 4 of them, also Deox the main in - Pre out jacks, you will have to pull the horseshoe jumpers out to do that.

Heres what I use, there are 6 transistors and some caps if you want to go that route

http://www.kallhovde.com/pioneer/sx-950smhires.pdf

equalizer.jpg
 
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