Pioneer VSX-401 - No Rear Sound

[Bond--007]

Here is a short version of what happened and what has been done thus far.

I have a Pioneer VSX-401 receiver in my garage. Front speakers A in the workshop, Front Speakers B in the rear of garage bay. Rear speakers are in the front of the garage bay. this way I have sound going back and forth between until I select B for garage sound only.

I was working on the electrical service in the garage with music playing. I accidentally turned off the breaker the receiver was plugged into. I immediately turned the breaker back on. I then noticed I no longer could hear from either rear speaker. I am able to get sound to come through if I unplug all speakers except for rears and turn the volume the whole way up. I can then hear music but it's really faint. This lead me to believe I didn't fry it as I wouldn't have any sound from the rear.

I have searched the net and could find a manual that was close. Nothing in there to reset receiver (as others have stated to do on other forums) or troubleshoot the issue properly outside of "make sure cables are plugged in"

Leon
Mont Alto, PA

 

[TLS Guy]

Here is a short version of what happened and what has been done thus far.

I have a Pioneer VSX-401 receiver in my garage. Front speakers A in the workshop, Front Speakers B in the rear of garage bay. Rear speakers are in the front of the garage bay. this way I have sound going back and forth between until I select B for garage sound only.

I was working on the electrical service in the garage with music playing. I accidentally turned off the breaker the receiver was plugged into. I immediately turned the breaker back on. I then noticed I no longer could hear from either rear speaker. I am able to get sound to come through if I unplug all speakers except for rears and turn the volume the whole way up. I can then hear music but it's really faint. This lead me to believe I didn't fry it as I wouldn't have any sound from the rear.

I have searched the net and could find a manual that was close. Nothing in there to reset receiver (as others have stated to do on other forums) or troubleshoot the issue properly outside of "make sure cables are plugged in"

View attachment 18449
Leon
Mont Alto, PA

You did fry the rear amps somehow. Hard to know what to advise without a service manual, but they never issue them. I suspect you will have to make do without the rear channels.

Too bad you did not leave the breaker off longer. You created a surge, by connecting and disconnecting an AC circuit. When you do what you did you get big back EMF spikes from quickly making and breaking an AC circuit.

 

[TLS Guy]

OK. I have found the circuits for your receiver.

If you register with Hi-Fi engine you can download the circuits here for free.

The front channels are discrete transistor 100 watt per channel amps. The rear channels are only 15 watt plus 15 watt. The rear channels are powered by a singe dual channel power amp integrated circuit. This is what you have fried and it needs replacing.

It is a NEC UPC 1070 OH.

Since this has both channels on one chip that is why you lost both rear channels when you fried it.

Unfortunately that chip is no longer available. I have done a search including sites that have old chips and I can't find it. Unless you find one on eBay or get lucky that unit is not repairable.

The other issue is that you need to have the skilled set and equipment to replace in IC.

 

[Bond--007]

OK. I have found the circuits for your receiver.

If you register with Hi-Fi engine you can download the circuits here for free.

The front channels are discrete transistor 100 watt per channel amps. The rear channels are only 15 watt .......................

Thx for the help. I ended up picking up a VSX-D906S to replace this unit for $20