• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Pioneer SX-1010 no sound

Hard to say.

The bottom of the board where the pot ground pins themselves come through is accessible, and that ground checks out ok, and if the pot elements themselves lost their connection to the ground terminal, things would be acting quite differently.

There is wiring going off to the loudness switch that could be picking up noise, or the grounding of the volume control board or the loudness board or a combination thereof could have a problem, or the front plate of the chassis itself (depends upon the construction) could have a problem.

A signal ground going to the chassis at the wrong place (not the star point) could also cause problems. As opposed to the "isolated" grounding of the pot or switch bodies.

Shorting 3, 4 & 5 just plain kills all audio coming in after the volume control.

Plus I don't have an idea of the relative level of the hum, and the touching of the chassis and pots affecting the hum puts it in a nasty diagnostic situation.

Compounding that is the fact that the board the volume control is on (switch circuit assembly aws-072) has many many wires that are sensitive to noise coming in, with grounds that are not terminated (on purpose) and the board has a complete system of ground "fingers" between signal carrying traces.

That's why I wanted only speakers and power being the only connections to the unit while testing.

edit: if there are florescent lamps close to where you are working, merely the bottom of the chassis being open and unshielded by the bottom plate could be doing it to you, so you could put the plate back on with all the screws, and turn out the lights in the area as a check. The wooden top of course makes little difference...




I would like you to dial up the hum, and then try turning on and off the tape 1, tape 2, 4ch adapter and NR adapter switches to see how that affects the hum. There are 16 possible combinations... then try two different things with the jacks for them on the back: one is taking a pair of interconnect cables and on each of the four plug sets testing the hum with the outs to ins of that plug set connected together. The other is making a set of shorted RCA plugs and plugging them to the IN side of each plug set.
 
Last edited:
markthefixer said:
Hard to say.

The bottom of the board where the pot ground pins themselves come through is accessible, and that ground checks out ok, and if the pot elements themselves lost their connection to the ground terminal, things would be acting quite differently.

There is wiring going off to the loudness switch that could be picking up noise, or the grounding of the volume control board or the loudness board or a combination thereof could have a problem, or the front plate of the chassis itself (depends upon the construction) could have a problem.

A signal ground going to the chassis at the wrong place (not the star point) could also cause problems. As opposed to the "isolated" grounding of the pot or switch bodies.

Shorting 3, 4 & 5 just plain kills all audio coming in after the volume control.

Plus I don't have an idea of the relative level of the hum, and the touching of the chassis and pots affecting the hum puts it in a nasty diagnostic situation.

Compounding that is the fact that the board the volume control is on (switch circuit assembly aws-072) has many many wires that are sensitive to noise coming in, with grounds that are not terminated (on purpose) and the board has a complete system of ground "fingers" between signal carrying traces.

That's why I wanted only speakers and power being the only connections to the unit while testing.

edit: if there are florescent lamps close to where you are working, merely the bottom of the chassis being open and unshielded by the bottom plate could be doing it to you, so you could put the plate back on with all the screws, and turn out the lights in the area as a check. The wooden top of course makes little difference...




I would like you to dial up the hum, and then try turning on and off the tape 1, tape 2, 4ch adapter and NR adapter switches to see how that affects the hum. There are 16 possible combinations... then try two different things with the jacks for them on the back: one is taking a pair of interconnect cables and on each of the four plug sets testing the hum with the outs to ins of that plug set connected together. The other is making a set of shorted RCA plugs and plugging them to the IN side of each plug set.
Click to expand...

This unit did not come with a bottom cover. I need to find one or have one made. I have it raised away from AC on a rack, about the best I can do for now.

Turning off lights in workroom, which includes 1 set of floursecents, did not reduce hum.

Turning on and off the 4 switches only creates crackling over the speakers as I touch the switches. No other change.

With ins and outs connected on the 4 Channel plugs, the buzz gets slightly higher in pitch switching the Dolby switch to on. No other variances with switches other than crackling with touch.

With ins and outs connected on the Dolby plugs, the buzz gets slightly higher in pitch switching the 4 Channel switch to on. No other variances with switches other than crackling with touch.

For the shorted plugs it kills the buzz when that switch is turned on.

The Tone defeat switch is causing a loud pop through the speakers. Louder from off to on. I don't think this was happening before. It sometimes engages the prot relay for a second. And doesn't sound too good for my test speakers.
 
The tone defeat pop probably calls for a recap of the tone board, it probably is just one channel. Leave the tone off for now.

What I would do now if it were on my bench, would be to make up a "battleship braid ground" - a very heavy, insulated ( to avoid short circuits as it draped around) ground wire with a very stiff alligator clip on one end, soldered to the star ground point on the other end. You can use a 14 gauge wire....

Then I would clip this onto the various suspect grounds we have already checked from the volume control board (5 of them I think) and the loudness switch board, to see if any effect could be noticed. We are looking for "weak solder joints, bad foils etc...

(I really would use my 4 wire milli/micro ohmmeter to check ground resistances to the star point, but not many people have one of those puppies..., so this should substitute)

http://en.wikipedia.org/wiki/Four-terminal_sensing
 
markthefixer said:
The tone defeat pop probably calls for a recap of the tone board, it probably is just one channel. Leave the tone off for now.

What I would do now if it were on my bench, would be to make up a "battleship braid ground" - a very heavy, insulated ( to avoid short circuits as it draped around) ground wire with a very stiff alligator clip on one end, soldered to the star ground point on the other end. You can use a 14 gauge wire....

Then I would clip this onto the various suspect grounds we have already checked from the volume control board (5 of them I think) and the loudness switch board, to see if any effect could be noticed. We are looking for "weak solder joints, bad foils etc...

(I really would use my 4 wire milli/micro ohmmeter to check ground resistances to the star point, but not many people have one of those puppies..., so this should substitute)

http://en.wikipedia.org/wiki/Four-terminal_sensing
Click to expand...

Battleship ground has not revealed any weak grounds on the boards. Is there a way to definitively eliminate the volume pot as the culprit? The buzz seems to originate there.

EDIT: When I put my hand near the volume pot board traces it increases the volume tremendously.
 
Last edited:
The volume pot is an acv-134, and is found in the sx-737, sx-838, sx-939 and sx-1010.

Thus until we find a donor unit, we're stalled.

It is a dual 250k ohm pot with ("flying") loudness taps.

Is the rotation smooth? or are there intentional "steps" in it's rotation?

It would be a real disappointment to go through all the trouble of finding and replacing the pot, only to confirm that the problem still exists.
 
Last edited:
markthefixer said:
The volume pot is an acv-134, and is found in the sx-737, sx-838, sx-939 and sx-1010.

Thus until we find a donor unit, we're stalled.

It is a dual 250k ohm pot with ("flying") loudness taps.

Is the rotation smooth? or are there intentional "steps" in it's rotation?

It would be a real disappointment to go through all the trouble of finding and replacing the pot, only to confirm that the problem still exists.
Click to expand...

The rotation is not smooth. It feels gritty and light, compared to the smoothness and heavyness of the balance pot. Is it possible to use too much De-Oxit?
 
Who did you order it with? Some places will take an (automatic) order and then report "no longer available" in a few weeks. Others though, get units and break them down for parts.

Faderlube afterwords in all pots.

deoxit removes the old lube, which would have gotten in the way of the metal cleaning process.

I guess we wait for the new pot, unless you want to recap the tone controls (pop on tone engage) but there will be a parts shipping delay on those, too.

Some could say that we should read voltages on the tone controls internal power (+/-13V) on the off (small) chance that they are incorrect, and is reverse biasing the blameless coupling caps. BUT the fix for THAT is new power filter caps on the tone board, which are done in a recap anyways.

I just happened to have the cap list around:

board cap uf v desig uf v part number price ea
control amp
awg-027 c1 0.33 25 cssa 0.33 50 667-ECQ-V1H334JL 0.15
awg-027 c2 0.33 25 cssa 0.33 50 667-ECQ-V1H334JL 0.15
awg-027 c7 100 10 cea 100 25 647-UPW1E101MED 0.26
awg-027 c8 100 10 cea 100 25 647-UPW1E101MED 0.26
awg-027 c13 2.2 25 cssa 2.2 50 647-UKL1H2R2KDDANA 0.21
awg-027 c14 2.2 25 cssa 2.2 50 647-UKL1H2R2KDDANA 0.21
awg-027 c15 4.7 35 cea 4.7 50 647-UPW1H4R7MDD 0.14
awg-027 c16 4.7 35 cea 4.7 50 647-UPW1H4R7MDD 0.14
awg-027 c23 4.7 25 ceanl 4.7 25 647-UKL1E4R7KDDANA 0.17
awg-027 c24 4.7 25 ceanl 4.7 25 647-UKL1E4R7KDDANA 0.17
awg-027 c25 10 16 cea 10 16 647-UKL1C100MDDANATD 0.08
awg-027 c26 10 16 cea 10 16 647-UKL1C100MDDANATD 0.08
awg-027 c29 100 10 cea 100 25 647-UPW1E101MED 0.26
awg-027 c30 100 10 cea 100 25 647-UPW1E101MED 0.26
awg-027 c31 4.7 35 cea 4.7 50 647-UPW1H4R7MDD 0.14
awg-027 c32 4.7 35 cea 4.7 50 647-UPW1H4R7MDD 0.14
awg-027 c39 4.7 25 ceanl 4.7 25 647-UKL1E4R7KDDANA 0.17
awg-027 c40 4.7 25 ceanl 4.7 25 647-UKL1E4R7KDDANA 0.17
awg-027 c41 10 16 cea 10 16 647-UKL1C100MDDANATD 0.08
awg-027 c42 10 16 cea 10 16 647-UKL1C100MDDANATD 0.08
awg-027 c45 100 10 cea 100 25 647-UPW1E101MED 0.26
awg-027 c46 100 10 cea 100 25 647-UPW1E101MED 0.26
awg-027 c47 2.2 25 cssa 2.2 50 647-UKL1H2R2KDDANA 0.21
awg-027 c48 2.2 25 cssa 2.2 50 647-UKL1H2R2KDDANA 0.21
awg-027 c49 47 16 cea 47 50 647-UPW1H470MED 0.25
awg-027 c50 47 16 cea 47 50 647-UPW1H470MED 0.25
awg-027 c51 47 16 cea 47 50 647-UPW1H470MED 0.25
awg-027 c52 47 16 cea 47 50 647-UPW1H470MED 0.25

I haven't checked these numbers against out of stock caps.....
edit: I just did and they have all 28 in stock!!

and all that.. is about 5 to 6 bucks in caps.....
edit: $5.26 cost.... not bad....

here's the Mouser.com EZbuy's BOM text block:

667-ECQ-V1H334JL
667-ECQ-V1H334JL
647-UPW1E101MED
647-UPW1E101MED
647-UKL1H2R2KDDANA
647-UKL1H2R2KDDANA
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UKL1E4R7KDDANA
647-UKL1E4R7KDDANA
647-UKL1C100MDDANATD
647-UKL1C100MDDANATD
647-UPW1E101MED
647-UPW1E101MED
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UKL1E4R7KDDANA
647-UKL1E4R7KDDANA
647-UKL1C100MDDANATD
647-UKL1C100MDDANATD
647-UPW1E101MED
647-UPW1E101MED
647-UKL1H2R2KDDANA
647-UKL1H2R2KDDANA
647-UPW1H470MED
647-UPW1H470MED
647-UPW1H470MED
647-UPW1H470MED


It CAN'T get any easier than this....
 
Last edited:
Thanks for the BOM list. I will order at some point to eventually recap tone board. Bypass for now until I can fix the buzz issue. Sooner if buzz appears to originate there.

Volume pot is used part from a 1010, tested good by someone I believe knows these systems. Hopefully it helps.
 
nbndtrain said:
Thanks for the BOM list. I will order at some point to eventually recap tone board. Bypass for now until I can fix the buzz issue. Sooner if buzz appears to originate there.

Volume pot is used part from a 1010, tested good by someone I believe knows these systems. Hopefully it helps.
Click to expand...

The replacement volume pot made no difference. Possibly time for a new thread? Start over from the beginning with troubleshooting buzz? I think it could be helpful if I linked to some video with audio. What specifically would help in determining cause?
 
You must log in or register to reply here.
Back
Top Bottom