0x0022 - Pioneer SX-780 Repair
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- Опубликовано: 9 мар 2018
- I set out to resurrect a Pioneer SX-780 I got recently.
This was a very satisfying video to make. Rescuing an old worthwhile device that could be destined for the trash can is one of my favourite activities.
I wasn't sure if I was going to be able to repair this or not. When I just thought the problem was because it was rained on I was concerned that it could be anything on the board. But discovering I wasn't the first to make an attempt really changed the game. Picking up in the middle of another person's project is always a gamble. You don't know if they have made things worse or not. The missing transistor was a fairly alarming example of just that.
In the end I was able to get it done with some research and probing all around(I figure 10m of probing footage was better left on the cutting room floor.) and referring to the very handy schematic. 
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Bravo! I was so happy to hear that thing make sound! As an electronics repair guy myself, I can totally appreciate how satisfying it must have felt when you fired that thing up and it worked! Congrats on the repair.
That's an amazing skill to be able to hunt down the trouble, fix it, create your own solution and then realize fruition. Fun stuff!
Quickly becoming my favorite channel. This was also extra fun to watch as I have a unit almost identical to this, haha.
I have several 50 and 80 series SX's in my collection.
Good to see you revive this 780 gem !
Thanks for the video.
The SX-780 is a bangin' little receiver, even at 45 watts per channel. I push a pair of HPM-100's and a pair of HPM-60's with mine and it sounds fantastic. I'd love to see you troubleshoot more old receivers like this. I bought a 780 just like this about 5 years ago and one of the STK's were blown. I replaced it, but everytime I would turn the volume up and then back down, it would pop the new STK. I'm sure there was something upstream that was failing to regulate the voltage, thus blowing the power pack each time, but I just couldn't figure it out with my lack of troubleshooting skills. I ended up selling it to a guy in Maryland and he had it fixed in no time. You're video makes me want to pick up another one and try it again. I have subscribed and look forward to seeing your other videos. The video that originally brought me to this one was the speaker recap on the Technics. I am getting ready to recap my HPM-100's and wanted to see someone do it to give me a little more confidence. Thank you.
This is something Lazy Game Reviews would love!
He actually owns an SX-1050 himself.
Have had my 780 since 1980. New. Still going strong in the man cave. Conseratively rated output. Kicks butt on my HPM-100'S. My power safety relay failed also, at about 7 years old. Otherwise, no other issues. Love Pioneer!
LGR is drooling about that case
My father had one of these in the early 80s. I have many fond memories listening to music on it and still think it's one of the most beautiful pieces of audio equipment ever made. I wish it hadn't gotten tossed in the 90s. :(
So satisfying to see it working at the end. This is my new favorite channel
I love seeing videos like this, glad you got it going
I have the exact same model, picked it up three years ago! Love it!
I also have the Audio Technica turntable from your other video.
Now I'm looking for a CT-F1000 Tape Deck in a wood case!
so satisfying ...my grandfather had this same receiver in his smoking parlor. Was so intrigued by it as a kid
Very well done! I wish I had a clue about electronics, or a really cool friend who did! I have lots of vintage gear so this video is great to watch.
So back in the day , early 80’s , like 81 , 82 , my buddy had this exact receiver hooked to a pair of Cerwin Vega HED’s , 12 inch , and a technics direct drive turntable. Man it was beautiful. I had the 690 , which was the same as the 680 , but a black background , 30 Watts per channel. My dad bought it for me for eighth grade graduation. These were awesome receivers !!
You have a great dad
@@user-mv5bu2kk8b how bout it man. He took me to “ Playback “. That was our local stereo store. Bought me that receiver and a pioneer belt drive turntable. Dad was cool for sure !! Thanks.
Awesome video! Satisfying restoration ineed :D
I just love my Pioneer SX-750, great receivers.
Excellent repair, quality content as always, thanks Druaga2
I bought one of these a little over 20 years ago and could never get it working. The STK packs had both been blown out, but there was other stuff involved that I just didn't have the time to fix back then (plus I already had a better receiver). I ended up giving it to a friend who did fix it.
My dad has a very (if not the same) unit, still works. I used it when I was younger as my own sound system for my computer and video game console (and I'm 26, so semi-recently)
I've had the same Pioneer SX-780 i purchased in 10th grade.Still going strong.
I have an SX-770 in storage that needs work (probably needs to be recapped, for starters), but it's a great solid piece of hi-fi equipment. Take care of your SX-780, and it will treat you well!
Excellent troubleshooting.
Had one and HPM 60 speakers. Beautiful sound
Nice work!
my dad has a similar model. still going strong in 2019! not bad seeing that he bought his in 1968.
great job on tracking the issue down - --
Wow. A local electronic store. All gone in my area.
Hello I just found your channel love it thank you for sharing..
Awesome video
nice vid man
Well done! Thank you for the video. Like!
Yes, but WHY did the diode blow in the first place? Failing caps perhaps. Without fixing the actual reason it failed, the unit will likely fail again.
I would assume it was the bad transistor that a former owner removed. Those are a known common failure in this unit.
My Technics SU-X301 is my daily use amp, it's quite a powerful beast
Nice repair
I love my 780!
I really would like to be able to fix my old eletronics like that! Unfortunatly my eletronics knowlege is very basic and i only have a simple cheapo multimeter.
Great vid man!
Likewise man but i gotta admit i've been learning simply by watching these videos
rheffera I've learned a lot too. But not even close to what i would need, and not even enough to be confortable to dessolder components ans trying to diagnose some of my eletronics.
I have a Masters degree in business. So I thought, watch some videos and start restoring stuff. Nope! Been 2 years and still not half way there. But one day....
I’ve had this receiver since my father gave it to me in 1990. He bought it in 1968 or 69 he said. About 1996 the relay clock would take longer and longer. Then no click. Been holding on to it ever since. I have no skills. Could you advise as to how to fix? I think I could learn to fix it just need a push in the correct direction. Please help
I did a SX-5570 once that i got for free (black 980). Totally worth it, still working today.
This receiver reminds me of my old technics sa-700, except it has LEDs as the vu-meters (except for the tuning meters). Almost identical in design except for the inside of it. I wish I hadn't tossed it out when I blew an output transistor.
Yes I do have a good FM/VHF antenna connected.
SX-1250 owner checking in...
SX-1980 owner checking in... trying to show off? (honest to truth) I used to own SX-1250 though.
I had one very similar but it was a Technics model damn transformer was burnt to hell in it. I managed to slap some random one in it from so crappy shelf stereo and it worked quite well. did not have enough current tho to really turn it up. them old school darlington power packs were monsters tho. think it was 75 wpc
Good video. Thanks.
I can't believe how much packaging went into that tiny diode ! What a waste.
Mine is showing exact same systems do you think it’s the same problem ? Lamps come on but no source light
When I saw you open the package with the razor I had to hold my breath, all I could picture was the razor slicing you open. Great video however!
150 watts is about power consumption from wall outlet, not power output. Yes, 45 watts is rather conservative but at best, it's probably not much more. Certainly not 150 watts output. power being consumed by transformer's loss, radio, preamp, main amp, etc.... You also need to warn about use of CPU thermal paste. Some are conductive. Some hobbyist blew their receiver using it. I used white paste and it works just fine.
And I immediately spotted a missing regulator transistor that is notorious to overheating. Yes, I own 780 too for almost 20 years and still using it. I added a heatsink to it and it keeps on going.
P=VI
So the higher the Watt at a set point the higher the current flow thru a point is at a fixed voltage
My '78 SX 780, Wich had a great tuner , no longer centers the gauge, won't pull it in in FM Stereo, LED for stereo does not illuminate, and it won't play at all, with FM muting off
On, is what I meant.
My dad picked up an SX-750 a few years ago that worked great and then lucked out on a great deal on a working SX-1050, unfortunately that one blew it's power supply a few months later. At some point he'll probably fix it.
I just bought an SX-750. Weighs about 3 times as much as my Marantz SR-5100.
Hey awesome clip... is there a way to fix the static noise my right channel on one of these ? When i turn the volume it crackles my speakers, only on the right side though.
Any idea why a 424 would have no display?
Checked the obvious its all good (fuses bulbs etc)
That was great. One little diode.
i think id've bent the other heatsink fin in on the other side just to match, it hurts my soul leaving stuff like that odd
Beautiful! I had one of these when I was kid, got it for Christmas. I loved it, flicking the power lever up to turn it on was so satisfying. Sadly, my folks got rid of it when I went into the military for which I have never forgiven them. 😠
Mine has the exact same dead transistor, Mitsubishi D712, and I also don't hear the relay click on, can you list the replacement parts you used in this video?
Really great video. I have one ? about the speaker output check. Was it a 31mv ? If it was isn't that enough for distortion ?
You could just sandwitch the transistor between those heatsinks for maximum heattransfer
just got a Sx-780 turns on with a relay click but no sound or FM meter
Good catch! One diode, amazing. The packaging of the diode.... never seen such huge package for just one single diode. What did you pay for one diode?
Hmmm .. I have the same unit SX-780, but channel Left has some distortion, very noticeable in mids/voice. I assume I'll need new capacitors, but don't know much.
I have a solder gun and know how to use it, but haven't fix any vintage electronics so far. Can anyone give me a hint on what I should try?
I just bought a Working Pioneer SX-590 for $150 bucks plus $30 shipping. Super stoked!!
Mine is behaving the exact same way after buying it second hand. There isn't a clicking sound once I turn it on ,main light comes on but not the stereo and the indicators moving anymore :(
Im want to get it repaired asap.
Any special recommendations in hunting down schematics?
Great vid - subscribed! Curious problem on my SX 750 you may be able to help with. Fm tuner was getting stations fine - stereo light on steady - used to get 8 to 10 strong stations. . A month later, it has lost most of its ability to receive stations. Only the 2 strongest come in, the stereo light only occasionally flickers. I have tried several different antennas with the same result and checked the FM muting to make sure it was off. Everything else on the unit works like new and it is all original with no modifications. Why would the FM suddenly lose sensitivity like this?
Hate cleaning up someone else's mess.
I have the same receiver.
It was in a climate-controlled storage unitfor 10 years. Then in September 2019 I moved across the country and all my equipment was in an outside storage unit.
I turn it on, no power. I see that the 4 amp fuse on the bottom was no good.
I replaced it, and turned it on and saw the fuse blows with a flash. I did that 2 times, Same result. Any idea what would cause that fuse to blow?
I want to recap mine and it seems to get quite hot after half hour of use. I could spent money paying someone to recapp it?? It seems like it needs to be clearer although it gets loud!! Since you have same one would appreciate your input also my radio signial is brutal I get like one station. But it never use to be like that!!!
Reminds me of my 465B.
love your channel, im new to this vintage world. I want to buy a marantz pm-200 how can i connect it to active home studio monitors made for making music. they are JBL mk II 3 series speakers.the only monitor's connection is by XLR or balanced input jack.
What model realy did you use, I cant find one anywhere?
Are you planning on restoring it? Did you do an alignment?
12:40 Shout out to @Druaga1
I have got one of those as well. It was working but the issue is that there's a humming noise. I have no idea how to fix it but I suspect it's the power surprise. Also mines not as in pristine condition as yours.
Jacob Niemuth Culdnt be insulation problems? Or grounding problems?
I'm no expert, but it sounds like either a grounding problem or a bad solder joint somewhere. I have an amplifier with a few solder issues (produces a minor low hum), but it works though. I plan on fixing it one day.
whats the retail on this
Excelent I have the same failure 😀
How did you figure out the replacement transistor -- I believe that part has been discontinued
Hook an FM antenna up . Disappointment may creep back in.
My 780 just went mid song....both sides, I just lost sound. I still powers up, just no sound or movement in the vu's. Is it most likely the relay in your opinion? I still have radio signal strenth and all the lights. Any help is appreciated
Do you here a click after you turn it on? If not then it could be the relay. It could also be that transistor I was missing.
Both are likely suspects. The relay is known to be failure prone and that transistor is regarded as being under cooled.
@@TechTangents I'm not hearing one. It would most likely be that correct. The volume was half for an extender time. Im assuming both packs would not go at once.
The packs are probably fine. I would suspect the relay.
@@TechTangents Thanks...hope that's it. Do you recommend a source for parts?
I bought one from mouser, this is what I got: www.mouser.com/ProductDetail/omron/my4-02-dc48/?qs=NHN4o8quFyRXEZvz6CJ87Q%3d%3d&countrycode=US¤cycode=USD
I haven't installed it yet but I'm pretty sure it's the correct part. I would look around to double check.
i hat e to say it but the 150 watts is actually the consumption it uses from the power outlet
how can we purchase this kind of old music assets.
is there any centre or mail address for this
I have a 650 still going strong.
I don't understand why you start for Q25 transistor in particular... there a lot others. And why it take you to that bad diode.
with a small heatsink like that i would have been better to form a new one from a flat slab using just two 90 degree bends and you would have an almost exact duplicate.
Is there a difference between the Korean and Japanese made?
hi my name is ted i have that same receiver sx-780 since 1981 it stop working 9 years ago, i had it checked out and the eletronic place and they told me it needed two new darlington stk-0050 and two new 0.22 ohm k 02 watt resistors that are right next to the power packs, he said those parts were not available at that time when he checked it, well all these years went by and i manage to fine what i needed to fix this receiver, i put in the new power packs with out the resistors it works but has some distortion to it, is it possible that because i did not replace the resistors yet can this be causing that problem?? and also the speaker protection relay takes time to click on?? any idea on that too, i don't have the equipment you have to do the testing i need to do, but i do have a ohms tester and a Capacitance tester is there a way in your professional opinion to check it with the equipment i have, please let me know i really would appreciate it.
best regards
ted
Without being there the best guess I have is that you were sold fake darlington packs. That is unfortunately common now. Unless you could get a verified real OEM model the best I could recommend for a replacement is to try making a DIY pack. It's not easy, but people have started to make them. This is where I would start researching it: audiokarma.org/forums/index.php?threads/stk-0050-replacement-for-sx-780-and-others.721181/
hi thanks for getting back to me, the numbers on top of the darlington i got is a "D6F22". so the resistors that i did not put in yet will not cause this problem is what you are telling me right, they are not working, and do you have any idea why the protection relay for the speakers would take so long to click on i timed it and it was about 3mins, please let me know,
note; i am very new on doing stuff like this, that is why i am asking questions. i appreciate your help sir
thanks
ted
HI i just found a set of sanyo darlington power packs stk-005011 was is your opinion on these?? please let me know.
thanks ted
I'm not an expert on the SX-780 and without being there to trace down problems it's really hard to say. The people on audiokarma are usually very helpful to people who have problems like yours. They know more common failures and would have a better guess than I would.
ok cool thanks i will try them i appreciate all your help.
ted
Did anybody notice the cap that was oozing crap out the top?
was that pioneer also called a Fisher?
Absolutely not!
schematics ftw
Does anyone viewing this channel know if someone has restored FM reception to a 780? Mine works perfectly except for the FM section. Thanks.
Exact same issue, inherited my Mom's SX780, purchased new in 78.
@@1972mercurycougar I finally took my unit in to a shop and got it fixed. It works fine now. Alas... just the other day one of my channels blew out. Probably one of the two Darlington Pair transistors - THE weak link in this entire unit, the 780. The original transistors were good, but the cheap, Chinese after-market replacements are lousy and this is going to be a problem going forward, i'm afraid. This is the single worst problem with the Pioneer 780 receiver.
@@mic982 Yeah,i've had mine since i bought it new in '80 and i had to replace my Darlington's several times over the years.
@@patriciawilson9666 The repair shop tells me old 780's are coveted for their parts, not the least for the Japanese-made Darlington's. They say that some of the Chinese-built ones are OK but it's a complete crap shoot when installing them as most are lousy and short-lived. The Darlington's were a wonder when invented, but apparently hard to reproduce. Were that the Japanese were still making them, or electronic firms in America.
i restored my old sony cdp-312
Then you might enjoy my video re-calibrating my CDP-47: ruclips.net/video/eXUat23xNyg/видео.html
I already watched it! That video was the reason for restoring my Sony
Mentioning Druaga1 gets an automatic like. 👍
in think when Pioneer dropped the 50 series for the 80 series they got cheaper , the 50 series receivers had a much better build quality !
do you do customer repairs?
Is it just me or does the STK at 13:46 have really dodgy looking solder joints?
The two inner pins are meant to be not connected.
I did just look it up and it seems that the inner 4 are only used on the STK0050-II, and even then it's probably optional.
Just thought it was interesting that they'd have two pins with no pads on the board whatsover, and two with but they just didn't bother soldering the pins down properly. Made me think they should have been.
Yeah, it made me look up the datasheet when I first saw them as well.
How much
ruclips.net/video/ABay_Fgtwds/видео.htmlm13s First noise! \o/
wow, what a waste, packaging a single zener in a huge pack:/