Pioneer SX-580 No Sound

mscottdoran

New Member
Hi, I have a Pioneer SX-580 stereo receiver. I am not getting any sound output from either channel. I have tried both speakers A & B, and headphones, from all input sources.

I went through the Deoxit procedure, no help.

I have checked all of the fuses, and none are blown.

I have a DMM and an oscilloscope, and a little electronics knowledge.

I have found the wiring diagram for this model also.

I would like some help with the troubleshooting, if there is anyone out there who can walk me through it.

Thanks, Matt
 
I am sure you will find help there, in the mean time, elaborate, does it, as far as you can tell, tune an fm station, get a stereo light etc? and nothing including the headphones make noise?

if you tune it to an fm station and pass 'tape out' over to 'aux in' on another machine, do you hear fm? does flippin all the switches off an on do anything? snap crackle pop?
 
oh yes, tape mon, you can also try looping tape out over to tape in, left and right, using patch cords - any noise?
 
Ok, good ideas right off the bat, thanks.

With tape monitor button pushed in, red led "Tape Monitor" light lights up.
With tape monitor button out, green led "Source" light lights up.

Connected audio source to aux in on the SX-580, record out of the tape monitor from the SX-580 to an aux in of another rig and I get sound.

With function switch on fm and am I get sound out of the other rig also.

So, no sound out of the receiver outputs.
Thanks so far, any further advice?
 
Also, no crackling or pops when the switches or buttons are exercised.
No deflection on either left or right power meters.

I do get a quick little needle deflection on the power meters when the speakers a and b buttons are cycled.
 
well there is a service manual on the AK database (search the early stickys in the solid state forum - file 78. (edited to add: sorry Im an idiot, sticky in solid state forum for support the database, link to database inside, select pioneer manuals, page 3 or so, file number 78/125 is the sx580SM)

Its a righteous scan - it blows up well.

If people started telling you where to probe and things like that, could you read the SCM, line it up to parts on the board and poke at the right pins?
 
Yes, I have the service manual, and I can basically read it and find where to probe. I would need to know what voltages to find where.

Also, I tried looping the tape monitor from play to record with patch cords and got no noise.

Thanks
 
talk him though hum injection with his fingers into the power amp input (pins 48 and 50) AFTER getting all the powers supply voltages correct.

There's a muting circuit iirc that if it looses a particular voltage, it is forever silent. -22v on pin 47. Q510, q502, q503, q504.


13v at d309 banded end and it's a DIFFERENT +13v than the q401 +13.6v
 
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Mscott....hint: always do what MTF says....

so, before you poke and prod, tell us about your meter, it really should be digital, and it would be way nice if it auto-ranges - does it auto range volts or does it have settings like 2000m, 20, 200 etc for dc volts?
 
It's a Fluke 179, it will auto range dc volts, but it does have a dc mV setting.
It also has capacitance, and diode testing.

When testing for voltage, I assume I can clip on to the common heat sink, which the schematic shows as ground. Correct me if I am wrong.

Thanks
 
without looking at it, Ill say 'probably so', I am travelling for the day starting in like 5 mins, when I get back in I will clip-art the part of the SCM/PCB you need to see to start poking.

auto range DC is best, most of what you are going to see is in the +/- mv range up to the rail voltage. We will never see a large 3 digit dc voltage on this.

If you can, download the PDF and blow up the PCB and schematic dealing with the preamp/amp areas such that you can read it easy. print it off so you can scratch some notes.

take the + (red) tip of the DMM and insulate it all but the very tip - some use e tape, personall I cut a wee bit of shrink wrap and shrink it (I have many leads so I sacrificed one for this) that way if you fat finger it less chance of flame and smoke.
 
I have the schematic, and PCB on PDF as well as printed out. I will protect all but the tip of the probe as you advise. Thanks for the help!
 
Yes, autoranging DMMs are best, especially if you're not sure what voltage to expect, and if you're less experienced. But unless you pay for a really good DMM, the autoranging function can be SLOW to respond. Basically they start at the highest range then step down until the range meets the reading, and by the time they get to mV you can forget why you were probing (jk).

Usually when I'm testing, i switch to manual ranging and set it to an expected level. That way I get a reading much more quickly.
 
talk him though hum injection with his fingers into the power amp input (pins 48 and 50) AFTER getting all the powers supply voltages correct.

There's a muting circuit iirc that if it looses a particular voltage, it is forever silent. -22v on pin 47. Q510, q502, q503, q504.


13v at d309 banded end and it's a DIFFERENT +13v than the q401 +13.6v

I read -21.97v on pin 47.

I read +0.765v on the banded end of d309. Please advise, thanks.
 
What is the condition of R348? It appears that the zener (S309) should have about 13V on the cathode (banded) end, and it seems to be supplied by R348.
 
What is the condition of R348? It appears that the zener (S309) should have about 13V on the cathode (banded) end, and it seems to be supplied by R348.

I get 0.833 vdc on one side of R348, the other side of R348 is at the same potential as the banded side of zener diode D309 about 0.765 vdc. Checked across R348 with meter on ohms (with power off) and I read 4.7 kohms (R348 still soldered in the board, so I may be reading resistance in parallel).

I checked D309 with diode check function with power off and still soldered in the board and it biases as such: black meter lead on banded end, red meter lead on grounded end = forward bias, reverse meter leads = reverse bias.

Correct me if I'm wrong, I should be getting 41.7 v on one side of R348, and 13 v on the other side of R348, right? So.. tracing back it looks like that 41.7 volts is coming off of a transistor downstream of the power supply area. Any advice from here?

Appreciate all of the advice, this is fun, thanks.
 
I believe you are correct - One end of R348 should have about 41VDC. It comes from the voltage regulator transistor Q402. Go back toward that and check the voltages around it for some idea of where the loss might be occurring.
 
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