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Pioneer SX-205 "Power Off"

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shorteddiode

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Wouldn't turn on so I checked the ac side and found a bad solder joint at the main transformer. Now it turns on for a short time then displays "Power Off" I found an amp tansistor bad and replaced it (Q3) a 4.7 ohm resistor (R365) and transistor (Q303) Replace the bad parts and still says "Power Off" after a few seconds. Tested electrolytics and didn't find any bad. Anyone have any ideas I Need Help!!!!!
Schematic at the link below.
I decided to replace all the power amp transistors so Q1, Q2, Q3, & Q4 have been replaced, still goes to "Power Off"

Error
 
Have a DC offset voltage at the output? If you have V at the output look for a bad component. Could be a R that change value. Try removing Collector V of all output and apply PWR. and see if protect circuit comes in.
 
Maybe the Service Manual will help. Send me a Private message with your Email if you can't download it here.
 

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  • SX-205RDS_Service_Pioneer.pdf
    2.6 MB · Views: 428
Thanks leal, I forgot about the DC on the output, I'll check it. I have checked the emmiter resistors in circuit and they both show 6 ohms, but I'l pull them and try that.
Also, Thanks to hotwaterwizard for the manual. I'll let you guys know what I find, Thanks Again
 
Well I figured it out, I pulled a rookie mistake. I checked my capacitors for good ESR but failed to check them for shorts. Found a filter cap with a dead short in it, what's the old saying about a dog chasing it's tail? Thanks for the help guys
 
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