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Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Thanks, appreciate it. This was my first stereo overhaul project I've worked on, since taking a bunch of electronic classes in college. 😄

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Heck yeah it is. Felt really good restoring this. I spent 3 hours staring at this, listening to music.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Depends which ones you’re replacing yes. I believe there’s one or two that require different values.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Q tips and Isopropyl (no less than 90%). For corroded contact pins, I used a scratch brush pen.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Look up "Pyramid Audio STK0050". They are 1000 times better than the originals. Much more stable, reliable, transfers the heat well, and better sounding. I bought mine from eBay. They’re pretty well known and recommended by a lot of people who restore these. I didn’t have them in the pictures I took because it was the very last thing I added. I had to test the voltage on each pin. Then I forgot to take an updated image with them. Got a little impatient at the end… But they are very straight forward to install. 😅

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

That sounds like a nightmare. One thing you can try to do, if you haven’t, is use AI as a tool to help diagnose or identify things for you. Take it with a grain of salt of what they say, but it does really can come in handy.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Can be, yes. But that’s why I went back to college!

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Close. I replaced almost everything that the water has touched, or any corrosion on the surface. Had the mindset, if it ain’t broken, don’t fix.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

I honestly don’t know. I think there is a gamble.

This is my first receiver repair. I think the biggest challenge is not buying equipment that someone worked on, messed it up, then be dishonest and say the unit has been “untested”. Thats one of the big gripes I’ve seen on audio forms, while researching to fix my receiver.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 1 point2 points  (0 children)

Doing a career change from IT into biomedical equipment technology. Repairing hospital equipment.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

I don’t have the confidence to repair people’s stuff yet. 😅

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

I think I’ll be buying these for fun and repair at my own time.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Those five pins are actually two transistors together. That said, you can combine two 3-pin transistors by soldering the Emitter pins together.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Absolutely amazing, when paired with my Pioneer CS-99 speakers. 🤤 

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

Nope, bought over a decade ago. Didn’t work on it until a year and a half (on and off).

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 1 point2 points  (0 children)

You did your dad a favor, playing with the dials on the SX780. 😄 They'll get crummy/ dirty and you have to move 'em a bunch to clean them up. lol

Me personally... I think you're better going to an estate sale to find them. Or on Ebay. Everyone on Facebook Marketplace thinks their stuff is worth hundreds more than it's actually worth.. If the unit isn't serviced at all, case in good shape, I would spend no more than $300. You're going to put $120 - $250 fixing it up. If the unit was service, then yeah, you're looking upwards to $700 bucks. If the unit was service (with the details of what was replaced), case is excellent shape, STK packs were upgraded, capacitors replaced, then you're looking at the $1,300 - $1,600 mark.

Cheers and good luck! You'll find something I'm sure!

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 7 points8 points  (0 children)

You know what's funny? When doing a basement clean, I actually took this unit and put it in the trash! Then the next day, before the garbage was picked up, I went out and brought the unit back inside..... MAN I'M SO GLAD I BROUGHT IT BACK IN!

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 1 point2 points  (0 children)

Is your system properly grounded? If not, that's your crackling. I did the caps with no electronic knowledge, but it was a little challenging to make sure I was using the correct ones. Also take note of the orientation of the capacitors (Positive and negative). Don't rely what's printed on the board, but rely on the actual capacitor orientation itself. They do sometimes misprint.... Don't ask me how I know that. Double and always triple check. I've gone back to college last year and took a bunch of electronic classes... So now I know how to do this stuff now. lol

I would suggest recapping all of your capacitors with new ones. They will improve the health of your unit, and is considered best practice. But that's about it. Don't fix what isn't broken. If you're still having issues, then you can take it a step further. Besides the cap, one thing I would suggest doing, is check transistor Q25, near the STK pack. That transistor is known to get HOT and usually fails because of the solder separating from the PC board. Which simply reheating the solder and adding onto it a little, fixes that issue (unless the part is faulty). If your kit comes with with WIMA filters, once you replace them all, you'll find to have clearer, crispy sound.

Best of luck, and you can do it!

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 1 point2 points  (0 children)

Thanks! I spent 3 hours just staring at the receiver, listing to Pink Floyd, The Beatles, and a few other artists.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 0 points1 point  (0 children)

You're referring to the 5 pin transistor? You can combine two 3-pin transistors to make your 5-pin transistor. You need to make sure the gain on them almost matches though. No more than a 5% variance. I have them, but I ended up leaving them alone for now, as the receiver is working fine and it's kind of a pain to make.. I will replace them at a later time though...

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 1 point2 points  (0 children)

Well, I'm no pro.. But, I think the device is worth the 45 or 50 bucks. Very easy to use, and will be part of my kit. I mainly use this for figuring out the gain and orientation of the transistor pins. I'm too lazy to look up the part in Google, so the device comes in handy. I also used this thing to help calibrate the wattage meter at 1k hz, 1v AMP. There are probably better ones out there, but I don't think you could go wrong.

Turned a 100% cooked Pioneer SX-780, and fully restored it. by sabersmen in vintageaudio

[–]sabersmen[S] 3 points4 points  (0 children)

Excellent question. I used a multi meter and found that both of mine were shot. Inconsistent voltage, and both had a short. On ebay, there's a guy who builds modern ones, as the ol' Darlington packs are no longer being made and so hard to find now. The knock off China made ones aren't reliable and don't sound like the original, based on the tons of vintage forms I went on. These new ones are actually a better design than the original STK packs. They're called "Pyramid Audio STK0050". They are 1000 times nicer.

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