Purchased A Pioneer SX-1280 Recently. Help Needed for Health Check.

[rcs16]

It is not the double box, it is that they need to be floated on foam, inserted to the sides as they show in the packing drawing. This drawing should be shown to all that attempt to pack. Sure a double box is good but the floating in box is what really counts.

Shit happens, with dummies at the wheel, it will live to see another day, if you can follow our advise. It is all in education. deep breathe, sigh. The DMM does not lie usually
So what is eBay charging for a used HS? Extrapolate your addition shipping charges to Australia.
Pioneer SX-1280 Receiver Output Heatsink Module

Condition:
“Pulled from a working SX-1280 Reciever,needs cleaning,good condition,1 fin has light loss of paint ”

Ended:
Jun 23, 2016 , 6:07PM

Price:
US $64.99

Shipping:
$51.55 USPS Priority Mail International

 

[Awesomeaudio]

PA3004 is on the protection pcb AWM-123. familiarize yourself with its location in the service manual
"Thing is though, the seller reckons it was "reconditioned"... My Ass !!"
I guess it depends on definition of recondition? It could mean spraying the pot/switches to clean them or it could be BS. Do not assume anything imo.
It might not be the PS, like I said, it could be something loading it down to blow the fuses. Pulling the power amp pcbs was method to help determine that.
People on this site have probably more experience in fixing these thing than you can find anywhere.
Up to you if you want to send it to someone who has never worked on one before
I did ask you to inspect the PS, you did, so you could focus on checking/re-soldering those joints, test for conductivity from the lead solder lands to the other ends where the traces go, to verify conductivity. I usually do measurements with power off using the ohmmeter, looking at the schematic to see if the readings make sense to what is going on in the circuit.
The ecaps are looking well used, that does not mean that they are the fault. I have many units older than your unit, QX-9900, still in working condition. I know the old Sanyo ecaps need replacing but it is still running. By replacing all the ecaps, you are pressing the rest switch on reliability but those comps could go on many years yet. It is your call on how much $ you want to sink into the beast.
There are two camps here, one to identify the fault and fix it, the other is the rebuild process with out identifying the faulty part. I have fixed a few stereo's, sometimes it was the 20 cent diode, others a bad solder joint and the list goes on. Figuring out which one(s) it is, is the challenge imo

I agree Rick. I appreciate your patience and understanding. I'm an amateur at this repair stuff but willing to give it a go. I've never had to dig deep into a unit before and yes it is better to find out what's causing the fault and rectifying it before a refurbishing can commence. That will be later.
I'll pull the amp pcbs and proceed as you said.
I downloaded some literature from hifi engine but the schematics are damned hard to read clearly combined with my frustration with reading glasses. Is it possible to get some decent schematics else where ?

 

[Awesomeaudio]

It is not the double box, it is that they need to be floated on foam, inserted to the sides as they show in the packing drawing. This drawing should be shown to all that attempt to pack. Sure a double box is good but the floating in box is what really counts.

Shit happens, with dummies at the wheel, it will live to see another day, if you can follow our advise. It is all in education. deep breathe, sigh. The DMM does not lie usually
So what is eBay charging for a used HS? Extrapolate your addition shipping charges to Australia.
Pioneer SX-1280 Receiver Output Heatsink Module

Condition:
“Pulled from a working SX-1280 Reciever,needs cleaning,good condition,1 fin has light loss of paint ”

Ended:
Jun 23, 2016 , 6:07PM

Price:
US $64.99

Shipping:
$51.55 USPS Priority Mail International

Yep I agree with the "Floating" of the unit inside two boxes.
That's how I received a 1250 and 1050 a couple years ago.
Both from the U.S and Both arrived in pristine condition.
There were enough peanuts to fill 2 of our council otto bins !
I wish I could find a heatsink at that price !!
2016 pricing lol.
It's the damned shipping that makes or breaks a deal. I just grin and bear it..
Onward and upward

 

[rcs16]

Wish we could find current pricing for the HS, but we know this stuff can be all over the map. But we have an idea at least.
Good attitude BTW.
I have the same docs as you = good enough for what we need to do. There is the big schematic which shows all the interconnects(wiring), switches, etc, (it is hard to read) but also print out the individual schematics of each assembly showing the sch and the parts layout. Much easier to read. It will be needed by anyone who services this unit. Start with the PS and PA schematics and we will go from there.
I understand your present knowledge level, we were all there at some point in time, so we have to improve it, if you are willing to learn this stuff.
I remember in grade 12 the electronics shop teacher bought the same receiver I had for the shop = cool we thought, listening to Super Tramp in shop. It was a SX-950. Now you know how old I am He gave us all copies of the big schematic to look at. That is what I liked about Pioneer, they were the only ones that gave out sch to owners. We did not have a clue how to read the schematic I think it was an exercise in identifying the symbols. It took a few more years before I had a clue and am still learning. I was hell bent on building a SX-1280 power amp section, never did but still have the special ips (input stage of the amp) bjts(transistors) and some of the other parts One day maybe, I have a couple of SX-1250 transformers to work with, it just takes time

 

[Awesomeaudio]

Thanks Rick.
Cool back story too !
I'll try have another crack at it tonight or tomorrow morning.
At the moment, It's Friday morning here 7.30am and currently at work so I'll post back when I've done something constructive.
Thanks mate

 

[rcs16]

And it is time to make dinner time over here, cheers, i'll stay tuned

 

[rcs16]

Suggest to take a look at this thread (maybe others too) as it was very well done and documented
http://audiokarma.org/forums/index.php?threads/pioneer-sx-1280-recap-and-restoration-thread.799204/

 

[Awesomeaudio]

Suggest to take a look at this thread (maybe others too) as it was very well done and documented
http://audiokarma.org/forums/index.php?threads/pioneer-sx-1280-recap-and-restoration-thread.799204/

Yes, I have read over this thread and it's one I have in my watches list. Matt makes it look so easy That BOM list is going to come in handy too.

 

[Awesomeaudio]

Ok so I've taken some readings in the meantime Rick.

The PA 3004 on the protection board as follows
Pin 1. 12.8v
Pin 3. 0.75v
Pin 4. 0v
Pin 5. 0v
Pin 6. -7.6v
Pin 7. 0.72v (If I read the drawing correctly I think this is AC volts) the print says AC 0.75v I think.
Pin 8. 7.02v ( This one was hard to read on the drawing. Not sure if it says 12v or 7.2v. I'm guessing it's 7.2v)

Now to the Power Supply Pins (ON DBT)
I took readings with both power amps removed, then with left connected only, then with right connected only, then lastly with both connected.
The readings didn't differ all that much in all scenarios so I'll post the readings with both disconnected and both connected.

Power Amps Disconnected. Power Amps Connected
Pin 1. 129.8 vac Pin 1.120.1 vac
Pin 2. 129.8 vac Pin 2. 120.2 vac
Pin 4. 0 vac Pin 4. 0 vac
Pin 6. 62.5 vac Pin 6. 58 vac
Pin 7. 62.5 vac Pin 7. 58 vac
Pin 8. 69.4 vdc Pin 8. 66.6 vdc
Pin 11. 33.4 vdc Pin 11. 32.46 vdc
Pin 12. 33.4 vdc Pin 12. 32.46 vdc
Pin 13. 33.4 vdc Pin 13. 32.46 vdc
Pin 14. 9.37 vdc Pin 14. 8.18 vdc
Pin 15. 9.37 vdc Pin 15. 8.18 vdc
Pin 16. 13.17 vdc Pin 16. 13.12 vdc
Pin 17. 13.17 vdc Pin 17. 13.12 vdc
Pin 18. 13.17 vdc Pin 18. 13.12 vdc
Pin 19. -0.003 vdc Pin 19. -0.002 vdc
Pin 20. -32.3 vdc Pin 20. -31.84 vdc
Pin 21. -32.3 vdc Pin 21. -31.84 vdc
PIn 22. -32.3 vdc Pin 22. -31.84 vdc
Pin 23. 0 vdc Pin 23. 0 vdc
Pin 25. -67.8 vdc Pin 25. -66.3 vdc

 

[tmtomh]

On getting your money back: Forget Fedex. No problem that you filed the claim, but just ignore that from here on out. Instead, file a claim with eBay. It will be resolved quickly and in your favor, and you should not have to pay for the return shipping. EBay probably will resolve it before Fedex even gets back to you with a decision (which decision likely will be "we're very sorry this happened, and we're not compensating you at all").

If you are feeling like you want to keep this unit and fix it, that's fine - but in that case you should decide how much you would have been willing to pay for this item in the condition it's actually in. Contact the seller and tell them you will be happy to keep the item and repair it yourself if they give you a partial refund of $XXX (XXX being whatever is necessary to get your out-of-pocket down to the number you think is fair given the actual condition of the unit). If they don't want to do that, then open the eBay claim.

The seller has absolutely zero leverage here. You are covered - as long as you pursue help through eBay (because you have zero leverage through Fedex).

If, in some unlikely event, you encounter problems with eBay, you have 180 days from time of purchase to file a PayPal claim too (assuming you paid with PayPal). So you're all good regardless.

Good luck!

 

[rcs16]

I agree as above, get eBay involved.

I'd call that a pass. PA 3004-7 is ACV.
Speaker relay is closing, with and without PA pcbs installed?
Again, your problem is no sound. It is not the PS, which is good.
So when you change the fuses and installed the amp modules the PS measures good, then did you test to see if the amp works again? if so run again, it maybe something intermittent, tired fuses?
If it does make noise then.
Have to check amp bias, offset, with PA pcbs installed, one at a time
check that you get o/p from pre-amp jumpers in the back (to an external amp test). Tuner/pre-amp mode test.
Check that it is not a bad speaker relay, in other words the contacts close properly. With the amp modules removed, you can measure the contact resistances between the pins of the amp, pin7 to the speaker jacks. Power has to be on for this test so the protest relay closes
Check that the speakers switches are working okay.Check that you get headphone op.
Clean those connector pins to the amp pcb's?

 

[Awesomeaudio]

It does seem that my Power Supply board has in fact had some work done. I neglected to acknowledge the witness marks on the foil side. Looks pretty rough with all that scratching.
So I've noted the following as having been replaced.
Q2, Q4, R6, R8, R12, D8, D10.
D8 has two diodes in series. Perhaps he combined 2 of lesser value to make it up.
That Scorch mark around the top of R14 looks to be a common thing on these. Mattsd's board also shows this.

Matt's Board.


Mine.

 

[Awesomeaudio]

On getting your money back: Forget Fedex. No problem that you filed the claim, but just ignore that from here on out. Instead, file a claim with eBay. It will be resolved quickly and in your favor, and you should not have to pay for the return shipping. EBay probably will resolve it before Fedex even gets back to you with a decision (which decision likely will be "we're very sorry this happened, and we're not compensating you at all").

If you are feeling like you want to keep this unit and fix it, that's fine - but in that case you should decide how much you would have been willing to pay for this item in the condition it's actually in. Contact the seller and tell them you will be happy to keep the item and repair it yourself if they give you a partial refund of $XXX (XXX being whatever is necessary to get your out-of-pocket down to the number you think is fair given the actual condition of the unit). If they don't want to do that, then open the eBay claim.

The seller has absolutely zero leverage here. You are covered - as long as you pursue help through eBay (because you have zero leverage through Fedex).

If, in some unlikely event, you encounter problems with eBay, you have 180 days from time of purchase to file a PayPal claim too (assuming you paid with PayPal). So you're all good regardless.

Good luck!

I have resolved the matter actually with both ebay and the seller. The seller was very decent enough to refund me an agreed amount to enable to get it back on track.
Ebay also refunded me some money to my surprise. So I get to keep the unit after all and no messy return to deal with.

 

[rcs16]

Oh ya someones been in there doing their handiwork it works, so do not worry until you want to rebuild it.. -68V supply was damaged and repaired.

 

[Awesomeaudio]

I agree as above, get eBay involved.

I'd call that a pass. PA 3004-7 is ACV.
Speaker relay is closing, with and without PA pcbs installed?
Again, your problem is no sound. It is not the PS, which is good.
So when you change the fuses and installed the amp modules the PS measures good, then did you test to see if the amp works again? if so run again, it maybe something intermittent, tired fuses?
If it does make noise then.
Have to check amp bias, offset, with PA pcbs installed, one at a time
check that you get o/p from pre-amp jumpers in the back (to an external amp test). Tuner/pre-amp mode test.
Check that it is not a bad speaker relay, in other words the contacts close properly. With the amp modules removed, you can measure the contact resistances between the pins of the amp, pin7 to the speaker jacks. Power has to be on for this test so the protest relay closes
Check that the speakers switches are working okay.Check that you get headphone op.
Clean those connector pins to the amp pcb's?

I forgot to mention that I did replace the bad fuses too during the pin probing process.
The protect relays energises yes with and without both PA's installed.
After posting the figures, I have since reconnected the speakers and using the same tape deck to test and the sound is back !
Perhaps those fuses were tired ?

I have to say, the sound isn't too bad for an old thing like this. The right channel isn't as strong as the left though. It has a slightly muddy sound. You can also see the difference in the output meters.
I tried a few different tapes to eliminate recording quality and all seems to point in the same direction.
The switches are a little scratchy, perhaps they were cleaned but not thoroughly enough. I'll have to do this at some point too.

I have also checked it via headphones. A ok.

The connectors were pretty clean too. Shiny looking pins. But I ran the eraser over them anyway.

The DC offset and bias I set when I first put it on the bench.
I wasn't keen to hook up my speakers with an unknown quantity.
I mentioned this in an earlier post. The DC was off the charts !
So I doubt anything has changed since, but I will do another DC and bias check just to be sure.

 

[Awesomeaudio]

Thanks for your help Rick. I appreciate your support.
And thank you to everyone for their advice re fedex and ebay.

I'd really like to refurb this unit. It really needs it.
That BOM Matt used should be fine as it's probably the most recent.
I'll start canvassing the bits through X-on here in Australia. They are a rep for mouser.
Looking forward to touching base with you all again soon.
Hope Zeb's ok too.
God Bless

 

[tmtomh]

I have resolved the matter actually with both ebay and the seller. The seller was very decent enough to refund me an agreed amount to enable to get it back on track.
Ebay also refunded me some money to my surprise. So I get to keep the unit after all and no messy return to deal with.

Very glad to hear! Now you can work on the unit in peace. Hope you get it back in great shape!

 

[rcs16]

300mV DC offset is not in the danger zone, but not where you would want to leave it either, so try to get it as close to 0 as you can. When you re-furb, use mullt-turn pots.
Hard to say where muddiness is coming from, pre-amp section? cleaning the switches/pot may fix this. Glad to hear you're going again, got to like the simple fuse fixes. hopefully it holds up.
Yup prayers for Zeb and his family.

Cheers
Rick