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Pioneer SX-1010 no sound

nbndtrain

nbndtrain

Well-Known Member
I won a local Denver SX-1010 on the bay yesterday for $72. Have wanted an affordable one for years.

I get audio from pre-outs, but not headphone or any speakers. The relay does not click, so appears speaker protection circuit is kicking in. No leaky caps that I have found, although 1 or 2 on the power supply circuit are bulging prety good. Do I start with aligning the power amp sections? I measured voltage across the main 18,000uF caps and get 53V from one and only 8V from the other. I have downloaded all the schematics and manuals, but this is all pretty new to me, so any help would really be appreciated.

At least all the lights work!
 
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nbndtrain said:
I won a local Denver SX-1010 on the bay yesterday for $72. Have wanted an affordable one for years.

I get audio from pre-outs, but not headphone or any speakers. The relay does not click, so appears speaker protection circuit is kicking in. No leaky caps that I have found, although 1 or 2 on the power supply circuit are bulging prety good. Do I start with aligning the power amp sections? I measured voltage across the main 18,000uF caps and get 53V from one and only 8V from the other. I have downloaded all the schematics and manuals, but this is all pretty new to me, so any help would really be appreciated.

At least all the lights work!
Click to expand...

I was watching that one to bid on, but not as closely as I could because of computer access problems (mine) from AKFest, otherwise we may have butted heads on that one, the price was within my bidding threshold....

But I was da## sure I was going to be fixing it, so when I saw your post, I just about fell off the chair laughing.......:lmao:

The bulging caps on the power supply board might just be the decorative cap on the capacitors... The heat shrink tightens up and makes it bulge.

The 8v vs 53v concerns me. it could be a bad cap or bad rectifiers, OR a partially shorted transistor that's loading that side down to 8 volts..

So we get all the power supply sections squared away first.

I need you to repeat the capacitor voltage measurements on AC volts, and I think we will need a series blocking cap (0.1uf 100v or greater) added onto the end of the test leads.

Also, with the power off afterward feel the capacitor and the big metal rectifiers on the fuse board for heat.

We will need to know the diameter and height of the big caps, and a picture of their connections would help because the mounting considerations are very important. Also the wiring to disconnect the tranbsistor load gracefully.


You can search through the forum here to see if anybody mentions replacement parts numbers and sources.

edit maybe from newark.com:
UNITED CHEMI-CON - 36DA183F100CC2A - CAP ALUM ELECT 18000UF, 100V, SCREW part # 95F4478 $24.02 each.

EchoWars said:
United Chemi-Con, 18,000uf 100V. 63mm x 105mm. Around $25 each, plus shipping. Newark, part #95F4478
Click to expand...
 
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Thanks Mark. I have been seriously following the 1010's for about a year now. Craigslist, Craiglook, eBay. With this one being in Denver, it was nice to not be burdoned with shipping $$. It is not pristine, actually missing the bottom panel! (Cooling mod) But, all switches and knobs are intact. The front panel is fairly nice, all lights work except FM, and the scratched cabinet can be brought back to life easily. Plus, it's nice to have a project.

I will follow these steps tonight, although I don't think I have any caps laying around. I have also seen replacement parts mentioned by EchoWars and will start documenting part #'s.
 
nbndtrain said:
Thanks Mark. I have been seriously following the 1010's for about a year now. Craigslist, Craiglook, eBay. With this one being in Denver, it was nice to not be burdoned with shipping $$. It is not pristine, actually missing the bottom panel! (Cooling mod) But, all switches and knobs are intact. The front panel is fairly nice, all lights work except FM, and the scratched cabinet can be brought back to life easily. Plus, it's nice to have a project.

I will follow these steps tonight, although I don't think I have any caps laying around. I have also seen replacement parts mentioned by EchoWars and will start documenting part #'s.
Click to expand...

maximum diameter and height will be your main considerations. You would want to disconnect the load (output) wire from the cap and see if the voltage goes back to normal. That's the idea about the picture...

edit: thanks EchoWars, yes 51 x 79mm at 16 bucks is a lot nicer.... :D
 
markthefixer said:
I need you to repeat the capacitor voltage measurements on AC volts, and I think we will need a series blocking cap (0.1uf 100v or greater) added onto the end of the test leads.

Also, with the power off afterward feel the capacitor and the big metal rectifiers on the fuse board for heat.
Click to expand...

Voltage test on two main caps, looking at unit from front left and right:
(I do not have the blocking cap you said to use for AC test, so this may be useless)
Left: DC 9.1, AC 19.4
Right: DC 53.1, AC 117.5

Caps not hot
Rectifiers not hot

DC voltages on bottom power supply circuit were all fairly close to the service manual specs.

Will post a bunch of pics tomorrow.
 
Here are lots of pics of the unit. With the flash, it does look like the left main cap, with the lower voltage, leaked out at some point. Please let me know if that looks to be the case, and what next steps should be taken.

Front panel
IMG_4391.jpg


IMG_4390.jpg


Cabinet
IMG_4385.jpg


Front
IMG_4380.jpg


Main caps (top)
IMG_4381.jpg


Main caps (bottom)
IMG_4375.jpg


Power Supply board
IMG_4376.jpg


Left Power Amp board
IMG_4383.jpg


Right Power Amp board
IMG_4382.jpg
 
I see crispy-crittered resistors on the driver board in the next to the last pic...
 
B3Nut said:
I see crispy-crittered resistors on the driver board in the next to the last pic...
Click to expand...

Ouch. It's at least 3 if not 4. Those aren't really easy to get to either. I'll have to figure out the least disruptive way to pull that board out. Is it preferred to pull the squared pins instead of messing with the coiled wire?
 
The heat sinks come out first, sort of accordion unfolding. Might be necessary to get the back panel out of the way.

Wires are not disconnected. Especially not unwrapped. The pin to board connections are strong in those models.

BE VERY CAREFUL OF THE BIAS DIODES - the thin wires going from the boards to the horseshoe shaped things screwed to the heat sinks. The wires love to break off flush with the body. THEN they have to be sent to me to reconnect flexible wires and mold on additional epoxy to the body. They are otherwise unobtainable.

The best strategy is to unscrew the diodes, and don't bend the wires within an 1/8 inch of the body of the diode.

And you do NOT jump ahead of my instructions - I am guiding you through a minefield, and first we get the various power supply sections working. In the process we will disconnect the power supply from the rest of the unit.

Before you order parts, let me know, so I can advise on additional parts.
 
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Hey mark, from a visual reference-learning moment, what tells you that the resistors are bad from the photo? What should I be seeing since this has been mentioned?
 
If you look at the lower left end of the right board, you will see several resistors are blackened. The circuit board has also been damaged. Also in the center of the board several have gotten hot as evidenced by the charred look at the center of the resistor.

The part mark is saying to be careful of is in the last picture, it's mounted to the heat sink. It has that 5N written on it. With wires running to the driver board. Remove it from the heat sink by loosening the holding screw, and moving it away from the screw. The wires are solid not stranded so are fragile. They will break if bent too many times. Both boards have one of those components mounted to the heat sink. They are no longer manufactured. Therefore replacements are not an option.

There is also evidence of over heating on your power supply board, upper left corner between a resistor and a diode. That is the board with all the black cans on it. It is mounted underneath. I'm working on one now. I expect Mouser to finish my parts order next week and can get back to work on mine.

If mark agrees with my choices, I can give you a list of cap part numbers for all the boards.

Good Luck. Ron.
 
That should be lower left corner of the left board under the green capacitor. Your military right.

Regards. Ron.
 
Thanks for all the insight so far.

I pulled the back plate off and have a little more room. However there is an orange wire from 3 to 7 that is strung through the chassis. It is soldered at 7. Is that from a repair, or is this meant to be unsoldered to get more room to work on the board? As is, I don't think I can easily get to those resistors on the lower left corner.
Also, my 1/4 watt 22 ohm resistors are tiny compared to these. Any issue with using modern, smaller resistors as replacements? I'm not interested in resale value.
 
nbndtrain said:
Thanks for all the insight so far.

I pulled the back plate off and have a little more room. However there is an orange wire from 3 to 7 that is strung through the chassis. It is soldered at 7. Is that from a repair, or is this meant to be unsoldered to get more room to work on the board? As is, I don't think I can easily get to those resistors on the lower left corner.
Also, my 1/4 watt 22 ohm resistors are tiny compared to these. Any issue with using modern, smaller resistors as replacements? I'm not interested in resale value.
Click to expand...

Use the modern 1/4w 22 ohm resistors.

What is your level of electronics experience? You seem to be jumping ahead of me, disassembling stuff. I shouldn't have appeared to sanction the dis-assembly with my detailed answer.

Eventually you will have to test all the output transistors on the heat sink, as well as the transistors Q7 to Q12 (you WILL replace the Q5 & Q6 2sc1451 transistors as a matter of course).

You need to check ALL resistors around each transistor when it is out. There are (my) lists of replacement parts to be dug up, or i can re-post as needed.

The outputs will be about 4 bucks apiece (and I'm betting they're lunched), the rest less than a buck usually - with this much damage, it may be a good idea to just plain shotgun most of the amp's transistors. Those that weren't destroyed may have been stressed, and just when you're playing it the loudest they could crap out.

I'm hoping you haven't disassembled much yet, I wanted to disconnect the amps from the big caps and see if the voltage on that cap came back up, which after seeing the fried 22 ohm resistors becomes MUCH more likely.

There are probably three red (or orange) wires connected to the big caps, one wire will be to the power supply, the other two wires will go to the output transistor collectors.

It is possible, if you insulate the sockets, to remove the output transistors instead of disconnecting the wires at the caps.

For now, study that testing link, and read through to post 11 for an explicit step by step testing guide with sample results. When testing your transistors, copy that text and edit in your numbers for easy and accurate reporting.

Right now this is the "feeling out and informational phase", where we take readings and survey the damage without twisting any screwdrivers. I've done this a LOT, and when directions are followed, have had excellent results.
 
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IMG_4410.jpg


Left Board, out of circuit

Q7 NPN:
black lead to base, red lead to collector, result = OL = No conduction
black lead to base, red lead to emitter, result = OL = No conduction
red lead to base, black lead to collector, result = 773
red lead to base, black lead to emitter, result = 784
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q8 PNP:
black lead to base, red lead to collector, result = 714
black lead to base, red lead to emitter, result = 743
red lead to base, black lead to collector, result = OL = No conduction
red lead to base, black lead to emitter, result = OL = No conduction
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q9 NPN:
black lead to base, red lead to collector, result = OL = No conduction
black lead to base, red lead to emitter, result = OL = No conduction
red lead to base, black lead to collector, result = 667
red lead to base, black lead to emitter, result = 686
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q10 PNP:
black lead to base, red lead to collector, result = 707
black lead to base, red lead to emitter, result = 713
red lead to base, black lead to collector, result = OL = No conduction
red lead to base, black lead to emitter, result = OL = No conduction
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q11 NPN:
black lead to base, red lead to collector, result = OL = No conduction
black lead to base, red lead to emitter, result = OL = No conduction
red lead to base, black lead to collector, result = 845
red lead to base, black lead to emitter, result = 760
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q12 PNP:
black lead to base, red lead to collector, result = 840
black lead to base, red lead to emitter, result = 847
red lead to base, black lead to collector, result = OL = No conduction
red lead to base, black lead to emitter, result = OL = No conduction
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Right Board, out of circuit

Q7 NPN:
black lead to base, red lead to collector, result = OL = No conduction
black lead to base, red lead to emitter, result = OL = No conduction
red lead to base, black lead to collector, result = 735
red lead to base, black lead to emitter, result = 755
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q8 PNP:
black lead to base, red lead to collector, result = 748
black lead to base, red lead to emitter, result = 770
red lead to base, black lead to collector, result = OL = No conduction
red lead to base, black lead to emitter, result = OL = No conduction
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q9 NPN:
black lead to base, red lead to collector, result = OL = No conduction
black lead to base, red lead to emitter, result = OL = No conduction
red lead to base, black lead to collector, result = 674
red lead to base, black lead to emitter, result = 697
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q10 PNP:
black lead to base, red lead to collector, result = 734
black lead to base, red lead to emitter, result = 740
red lead to base, black lead to collector, result = OL = No conduction
red lead to base, black lead to emitter, result = OL = No conduction
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q11 NPN:
black lead to base, red lead to collector, result = OL = No conduction
black lead to base, red lead to emitter, result = OL = No conduction
red lead to base, black lead to collector, result = 866
red lead to base, black lead to emitter, result = 875
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction

Q12 PNP:
black lead to base, red lead to collector, result = 845
black lead to base, red lead to emitter, result = 853
red lead to base, black lead to collector, result = OL = No conduction
red lead to base, black lead to emitter, result = OL = No conduction
black lead to emitter, red lead to collector, result = OL = No conduction
red lead to emitter, black lead to collector, result = OL = No conduction
 
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Got a question. Would it be prudent to lengthen the leads to the bottom of the driver board? This is easily accomplished from underneath. At that point, a couple of very accessible screws come out, and the board comes out for working on, but is still easy to test in circuit. It also obviates the need to remove the heatsinks, which is a PITA. I did this on my SX-1010 while my local tech and I worked on a similar issue, and it worked out well. I don't want to step on anybody's toes though.
 
nbndtrain, were those off readings done with the transistors out of circuit? Remember from the testing thread, in circuit can skew the readings.

And are you going to pull (mark the positions and what came from where first!!) the output transistors and test them?

IF you end up putting them (to-3 outputs) back in the sockets, even if for storage, be aware there are ridges in the sockets that fit matching indentations in the heat sinks, and tightening with them out of place will break the socket.

Right now both channels don't look good, yet one doesn't have any burn marks... That's why the removal for testing.
 
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