SX1050 power amp section goes silent

qguy

Super Member
SX1050 Speaker protection kicks in during loud volumes

My SX1050 is having an intermittent problem.

Connection: Sx1050's pre-out is connected to a powered subwoofers inputs. The output which is is fed back into the the POWER amp in.

On occasions the speaker connected to the SX1050 would go silent, but the subwoofer would still continue to play. I guess the problem does not lie in the pre-amp section but lies after the pre-amp

any ideas where i should be looking ?

The SX1050 has been recapped about 3 years ago.

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EDIT April 8, 2014

I noticed that when it goes silent the speaker protection kicks in and then would engaged again after a 1 or 2 seconds

I have resoldered all the transistors in the power supply board.
I have tested the unit without the SX1050 pre-amp and the problem still occurs

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"I guess the problem does not lie in the pre-amp section but lies after the pre-amp"

^^^ good guess.

I'd take the sub out of the picture for awhile, see how the 1010 does. If it's fine then look into the sub's internals or maybe the cable from the sub back to your amp and hope that it's not the amp. Good luck.
 
1. Check the DC offset on the speaker terminals and adjust as needed.
2. Examine the solder joints on the transistors in the power supply, the ones mounted on little heat sinks. Look for a dark ring around the component lead and re-solder as needed.
 
if the problem was in the power supply, the pre-amp should cease to function, Right ?
 
Ahh I see

The 1050s power supply has boards on the bottom and board on the top part. Which board should I check ?

Thanks
 
Ahh I see

The 1050s power supply has boards on the bottom and board on the top part. Which board should I check ?

Thanks

Check them both, this is a common problem with Pioneer. they run those transistors hot and they sort of de-solder themselves over time.
 
I removed the sub from the system and played for an hour with no issues, I connected the sub back in, so far no issues for about 10 minutes
 
Still playing flawlessly with the subwoofer connected.... darn it I "sort" of hate these kinds of intermittent problem...

Funny thing is, it is when you show off your gears to your friends is the perfect time for it to screw up, like what happened yesterday :(
 
If your sub has high level inputs for speaker wire you could wire your speakers to the A speaker outputs and the sub to the B speaker outputs.

That way you can isolate your receiver from the sub just by shutting the B speaker output on the receiver off.
 
Thanks for all your responses, I ruled out bad RCA as the chances of both left and right cables going bad at the same time is highly unlikely.

The pass through is a possibility.

The sub has high level inputs, but I use the RCA connection as the line out is a high pass filter at 80hz, I need this when watching movies to protect the bookshelves from very low frequencies.
 
I noticed that when it goes silent the speaker protection kicks in and then would engaged again after a 1 or 2 seconds

I have disconnected the subwoofer
I have resoldered all the transistors in the power supply board.
I have tested the unit without the SX1050 pre-amp and the problem still occurs

What else can I check ?

Thanks for all your help
 
the sx-1050 preamp output is taken to the subwoofer?

the preamp output goes into the subwoofer?

then the signal comes out of the subwoofer on other cables?

and THEN goes into the sx-1050 power amp input?

Please list the make and model number of the subwoofer for research.

because it seems to me if this is the case, that the subwoofer is adding subsonic almost DC to the signal going back and the protection is doing it's job, it cannot distinguish very slow powerful AC from a DC fault, this is due to the integrating time constants of the protection's DC detect circuit.

now, once the protect triggers, it should take the ** S * A * M * E ** amount of time to come back on as it takes to come on after the power is first turned on. If it comes back FASTER, there is a protect circuit problem.
 
Hi Mark,

SX-1050 Pre-out to Subwoofers INPUTS and then the subwoofers HPF (80 hz filter) out is connected to the main in of the SX1050.

Subwoofer is Rythmik F15

I already took out the subwoofer and placed the jumpers back in and I still get the same problem.

I removed the jumpers and connected my source directly to the power in of the SX1050 and I still get the same problem.

I will check the timing of the protect circuit tomorrow morning as it is night time and it takes a fairly loud sound to trigger the problem.

Thanks for responding !!!
 
Tested it just now, took about 15 minutes for the problem to arise.
The protect circuit when powering on took about 3-4 seconds to engage.
When the protect circuits kicks in when playing, it took about a second to re-engage

Testing was done without the subwoofer and using the SX1050 pre-amp connected to the main in of the SX1050 with factory supplied jumpers.
 
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The problem is in the receiver. Possibly a noisy transistor in the power amp stage, or it could be the DC offset needs to be adjusted.
 
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