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Help troubleshooting Pioneer SX-737 issue

Hi Everyone,
Happy holidays!

I recently got a Pioneer SX-737, it appears to be in fine working order: powers on, all lights work (tho phono bulb isn't lit). . . However, when all components & speakers are hooked up, not getting any output sound. . . Have something in phono, aux, & tape 1, so it's not a single channel issue. When on AM/FM, there is *no* signal strength indicated.

Speakers are in working order, were just fine with my previous Onkyo tuner. Only issue on the surface with the piece is that the "function" knob is missing, but it can be turned between functions with no problem.

I don't know much about these, have DL'ed the service manual to try & troubleshoot on my own, but any thoughts on where to begin or look at are appreciated.


magna98's picture

Help troubleshooting Pioneer SX-737 issue

After you've followed tbrander's advice, check the protection relay (ASR-007-0). It's next to the power supply. Tap it a few times with unit on and volume at one quarter. If nothing happens check it with your volt meter. Good luck!

Help troubleshooting Pioneer SX-737 issue

Ifyou haven't located the issue yet, I would suggest looking for a popped internal fuse, or a problem with the 13Vdc regulator. These regulator transistors, (usually a 2SD313, or 2SD325), and when they fail, they usually open Base to emitter. "0" signal strength deflection is usually a power supply issue especially if it is for both AM and FM. Of course other componnents on the regulator board could have failed as well, such as resistors or zener diodes (zeners short when they fail). Last but not least, becuase these regulators run very hot (usually mounted on a small heat sink), cold solder connections and burnt connections can be found on the regulator board as well

See. or listen for the protect relay engaging after about 5 seconds. If this works, it is almost for sure a regulator problem.

Good luch

If you need further advice, send me a mail at tbrander@aol.com