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

Awesomeaudio

Super Member
PART 1.

Hi Gents, I purchased this 1280 from ebay and was convinced by the seller that it would be packed well. Prior to this, I requested it be double boxed etc but this person completely ignored me and took it upon themselves to have it done their "own way".
It was taken to a FedEx in the local town and they supposedly packaged it "Professionally" as the seller described..
Well what do you know....

Yes. It did arrive damaged. It was packed on it's side inside a singular box with one layer of those foam bags around it. Due to it's weight and orientation the left heat sink took a hit and the bottom panel bent.
It had spent it's entire trip being dropped on and dragged on the heatsink !! AARRGHH !!!
The corner of the fin has snapped off. I did find it in the box. :rolleyes:
Anyway, As I pulled it out for further examination, the power switch had been bent over too.
Over all a pretty disappointing start.
What is the best way to go about getting compensation for this damage ?

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PART 2

Now.

With my suspicions growing, I decided to 1st, put it on DB just to be sure prior to power up and 2nd,

adjust the voltage tap from 120v to 240v and powered up. The bulb dimmed right down. Good News I think.

Next I thought I'd check DC at the speaker terminals and was quite surprised how bad it was.

I gave it around 10 minutes to idle.

Here's an extract from EchoWars' thread on this subject:
If you read:

0 - 15mV: Damn good!! If you read '0V', you may have a capacitor output, or your meter is set wrong

16mV - 50mV: An acceptable value, especially at the lower end of this range. 2nd harmonic distortion is probably twice to four times what manufacturer's spec calls for at higher frequencies. Probably not audible, as the distortion is mostly in the upper octaves. At the upper end of this range I begin to raise an eyebrow. :saywhat:

50 - 85mV: Something is certainly amiss, and while this is not enough to put your speakers or equipment in jeopardy, the amp is running nowhere near where it should. I'd venture to guess that most of the DC-coupled amps that are in use by forum members here fall into this range.

100mV to ?: A high enough voltage will cause the DC protection to kick in. This happens at a level determined by the designer, but is usually equivalent to about a diode drop (600mV)or so. Needless to say, if you are listening to an amp with 100mV or more of DC offset, you have no idea what the amp really is supposed to sound like. Indeed, some amps without a differential input are actually designed to have a bit of DC at the outputs, but this is triple-rare, and I don't think anyone here owns one. (in my book it's piss-poor design, but if you can sell it WTH..)


Here's the thread if you wish to read further
http://www.audiokarma.org/forums/index.php?threads/amplifier-distortion-dc-offset-and-you.5634/

So I downloaded the service manual to read about Idle current and DC offset Adjustments and set about doing just that.

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PART 3

After figuring out which wires to probe I set about making the necessary adjustments to bring it back closer to spec.

Idle Current: The Service manual calls for the potential difference on wires 12 & 18 (purple wires), 11 & 17 (green wires) to read 15mv on both Channels.

After having turned Vr2 fully Counter Clockwise and Vr1 to Centre on BOTH sides, I then made the necessary adjustments as per the instructions.
I did manage to get the Idle current bang on 15Mv after some trying.
The DC offset got pretty close to zero as I could get it, and far better than what it was !
Those Pots are very very touchy and hard to get accurate.
I then hooked up some Old Wharfdale Bookshelf speakers and a Very nice Nakamichi RX-303.

Turned it on and waited for the click and proceeded to listen to some music. I went through the controls and got a feel for this thing.
It sounded pretty fair considering the speakers and then after around 10 minutes, dead silence.
The output meters stopped too.
So I switched it off and waited a few minutes.
Turn it back on and I hear the relay click again and still nothing.
I went back in to check voltages on pins 17&18, 12 & 18 and now no more 15mv. Instead -0.00.
I'm baffled now. What could be wrong ??
Returning this is no option as I have too much shipping and duty in it.
I hope it's nothing too serious.
 
Can you adjust the DC Balance on those receivers?
I don’t have access to a manual.
If you can see if you can rock it from + to - or at least move it.
If it’s in protection and the fuses are good then it’s in the amp. Remember if it’s in protection you have to read DC Balance before the relay. It might be railed to one side.
 
Hi Zeb, and thanks. My knowledge is limited in the diagnostic sense.
This is what I followed from the service manual and was able to both DC and Idle pretty spot on.

SX-1280 Amp Adjustment Diagram.png
 
Can you read and post the protection board pins?
Chassis ground, red probe covered to the tip.
 
Found The Protection Board.
Meter set to Vdc not Mv
AWM-123
Readings As Follows.
Pin 1. 0.030v Pin 10. 78.1v Pin 19. 12.56v
Pin 2. 0.028v Pin 11. 0.029v
Pin 3. +77.9v Pin 12. 0.030v
Pin 4. -77.7v Pin 13. -0.001v
Pin 5. 0v Pin 14. -0.001v
Pin 6. 0v Pin 15. -0.022v
Pin 7. 0v Pin 16. -0.022v
Pin 8. 0v Pin 17. 13.22v
Pin 9. -77.9v PIn 18. 12.56v

Also Found two blown 1A fuses
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The protect voltages match the schematic.
the 1A fuses are F3,4 I assume, which means you have a power supply fault or something is shorting out the supply, that sucks.
I guess you could try to replace the fuses, then power up on a DBT and then measure the PS voltages.
You could look at the PS for signs of burnt components.
It was taken to a FedEx in the local town and they supposedly packaged it "Professionally" as the seller described..
If this is so I would contact FedEx and tell them that it was damaged in shipment due to there poor packaging and non-operational due to their handling. Pronto!
 
The protect voltages match the schematic.
the 1A fuses are F3,4 I assume, which means you have a power supply fault or something is shorting out the supply, that sucks.
I guess you could try to replace the fuses, then power up on a DBT and then measure the PS voltages.
You could look at the PS for signs of burnt components.

Hi Rick, I appreciate your support too. Thanks for the information. This unit looks pretty original even down to the black relays. There are areas of discolouration on some pcbs which doesn't fill me with confidence. I think the poor packaging job and rough handling has sealed it's fate and it's now in need of a full refurb I think.

If this is so I would contact FedEx and tell them that it was damaged in shipment due to there poor packaging and non-operational due to their handling. Pronto!

I have sent a message to the seller who originally took it to Fedex and I'm guessing she may need to file a claim. Is this correct ? I don't know as I've never had to deal with something like this.
What good would it do if I contact them myself ?
What are my chances on getting some compensation ?
I really don't want to send it back to the U.S as it would cost a fortune.
I'm happy to keep it as long as they can compensate me enough to get it back in shape prior to the damage.
 
So while I'm waiting for the seller to get back to me, I've filed an online claim to Fedex. I just need to get more supporting documentation regarding the extent of the damage and repair bill. What's the best course to take to get a repair quotation ? Anyone here able to do this or do I have to get it to a local repair shop. (These are rare as hens teeth nowadays in Sydney)
I have posted them the photos and proof of purchase.
 
Do as zeb suggested above, does not hurt to try. the protect relay is run off the -76VDC from the big ecaps, so if the protect relay, S20 energizes, I doubt that it is a protection ckt issue. the protect ckt does not run off the supplies with the 1A fuses.

You know the extent of the damage, supply pics as you have done. As far as a service quote, maybe you can ask a local repair shop for a quote (email) to repair it. Ask for their hourly rate, make an assumption it will take at least a 2-4 hours minimum to service the unit. I'd say roughly min of $300 ($75*4) for service. Most will probably say to bring it in for a quote which is a PITA, but your time, travel expenses should be part of the claim.
For the damaged HSink and switch that is difficult since these parts are obsolete, but you could look on eBay to see if any of the parts have been put up for sale in the past and use that as a reference for costs. Search eBay using the part numbers &/or description. I think you should be able to bend the switch lever back to normal.
Did you pay using your credit card?, if so ask them ?'s about such a claim situation. Visa has always been good to me with vendors, worth a try.

As for repairs, you can try to isolate the fault. Unplug the connectors from both of the PwrAmp pcbs, replace the 1A fuses and power up on DBT, check fuses again, check the voltages from the PS pcb. if all is okay, then reinstall the conns (clean the pinswith the pink eraser trick, while you have them out) to the PA modules one at a time, to see which one would cause the fault.
 
Hey while your doing that, read the PA3004 chip pins.
No shorts!
Do you mean the PA3001 on the tuner board ?
I don't see a PA3004 anywhere. There are four. PA 1001-A, PA1002-A and the PA 3001-A and one Labelled HA 1197
Can I read in situ or will I have to de solder it completely ?
Tuner Board ICs..jpg
 
Do as zeb suggested above, does not hurt to try. the protect relay is run off the -76VDC from the big ecaps, so if the protect relay, S20 energizes, I doubt that it is a protection ckt issue. the protect ckt does not run off the supplies with the 1A fuses.

You know the extent of the damage, supply pics as you have done. As far as a service quote, maybe you can ask a local repair shop for a quote (email) to repair it. Ask for their hourly rate, make an assumption it will take at least a 2-4 hours minimum to service the unit. I'd say roughly min of $300 ($75*4) for service. Most will probably say to bring it in for a quote which is a PITA, but your time, travel expenses should be part of the claim.
For the damaged HSink and switch that is difficult since these parts are obsolete, but you could look on eBay to see if any of the parts have been put up for sale in the past and use that as a reference for costs. Search eBay using the part numbers &/or description. I think you should be able to bend the switch lever back to normal.
Did you pay using your credit card?, if so ask them ?'s about such a claim situation. Visa has always been good to me with vendors, worth a try.

As for repairs, you can try to isolate the fault. Unplug the connectors from both of the PwrAmp pcbs, replace the 1A fuses and power up on DBT, check fuses again, check the voltages from the PS pcb. if all is okay, then reinstall the conns (clean the pinswith the pink eraser trick, while you have them out) to the PA modules one at a time, to see which one would cause the fault.

I had some time today to take off the wooden cover to inspect the power supply board and you were right. I did find some toasty spots around two resistors.
I do also recall this thing running pretty hot on the case area exactly where the power supply pcb after about 20 minutes on idle with nothing hooked up.

Looks like one of those got so hot it almost de soldered itself. Note the spatter. Wow. Also note the shrinkage on those caps too. This sucker was used really well.
There's no doubt that this unit is tired and in need of a full refurb. Thing is though, the seller reckons it was "reconditioned"... My Ass !!
It's ALL original.
I going to get a few quotes to have the power supply rectified to get it stabilised and have them interrogate it to determine any other issues then send the quote/s to the seller for a prompt reimbursement.
The part that really sucks is I'm going to have to lug this thing around. Damn it's heavy !

At this point I think I'll leave it until after It gets inspected and go from there. Better not mess with it too much before the tech sees it.
Hopefully after all this is over I can get the BOM prepared and either start the refurb myself or let the shop do it. See what happens.

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Rear PCB.jpg
 
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 :)
 
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This type of stuff is just infuriating. No double box, no deal. Hope you sent the idiot seller a strongly worded "I told you so".
 
This type of stuff is just infuriating. No double box, no deal. Hope you sent the idiot seller a strongly worded "I told you so".

Actually I did Mr White. Post sale , I sent them a message outlining my packaging expectation and my advice was ignored. This allowed those numb nuts at Fedex to determine that instead.
I really didn't need this right now, but I have to see it through so I can get some compensation for something thats both "Not as described " by the seller and the transit damage.
Talk about a double whammy !
 
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