SOLVED: Pioneer SX-737 LOUD Pops And Crackles In Phono!
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- Опубликовано: 6 янв 2022
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Pioneer didn't use the greatest transistors in the X3X generation of receivers, and this SX-737 is a good example of this. When the customer told me what was happening, I knew exactly what was wrong. I was correct about the issue, but I did not expect to find a leaking electrolytic capacitor inside! 
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I grew up around these. Love the old Pioneers, evidently by the price others get from, many love them too. In the world of forgettable AV receivers. This receiver is so honest and straight forward.
Nice work. It's good to see a young man doing this kind of work. Old guys like me who have done it for decades are falling like flies, so we need people to do this when we're gone. If you look at the leads of those transistors you replaced, you'll likely see black oxide on them. This is probably what you're planning on talking about in that next video. (Am I right?)
I've always called this "black leg syndrome." I replace such transistors on sight even if they're not making noise yet, because they will. The caps you replaced are in the ground leg of the negative feedback circuit of the phono pre. They failed because the transistors were intermittently feeding a lot more than 6 volts to them. Their value is critical because it sets the infrasonic rolloff frequency that helps keep warped records from sending powerful infrasonic signals through the power amp. When those caps failed, the negative feedback went way up and the gain went way down, which is why you didn't near the popping sounds at first.
Keep up the good work!
P.S.: You'll find such transistors in Pioneer RT-701's, 707's, 901's, 909's, and 1050's as well as in lots of other units from that era. I had to replace 22 of them in my RT-1050! I've even seen them in the differential input stage (long-tailed pair) of power amps. In that position, the popping noise is not affected by the volume control, but it tends to be quieter.
Very much honor a man with your knowledge. Thank you
@@missyounorm33 You're very kind.
Remember: Due to how capacitance meters operate, a capacitor that is leaking current (i.e. weakly internally shorted) will show higher capacitance. Always consider "overachiever" caps as extremely suspect.
Nice video of a swell component. The rec out feature was very rare in this time/price period. I know Yamaha had it on their later 1970's receivers. Pity this SX-737 didn't have pre out/ main in which would have increased its functionality. My first component receiver (after military service and broke) in 1974/75 was an SX-434, hooked to a BIC 920 and KLH 31 speakers. All for under $250. Loved that blue back lit dial scale, orange station pointer and red STEREO lamp.
The SX-737 is such a BIG receiver with only 35wpc. In early 1970's TOTL component receivers had under 40wpc and THD's of 1%. Man, how that changed by later 1970's. Amazing how these forty+ year old components can be restored to good working order. A credit to their build quality. I use an SX-434 in my kitchen hifi system. It drives a Nakamichi BX-1 cassette deck and Boston Acoustics A-40 and Synergistics S12B speakers. The little 434 can easily drive a 4 ohm load. Not like some amps of today. Still dig lookin' at the blue lit dial scale of my 30 series Pioneer.
I really enjoy your content. I put myself in the same category of hobbyist. I'm not to your level, but am learning all the time. So, thank you for being a great inspiration!
Nice deduction and thorough assessment, Aidan. That builds trust with your customers
I bought one of these from the Base Exchange when I was in Thailand during the VN war. It's such a beautiful classic Kenwood.
Thank you for your service to the Pioneer! Just got dads old SX-737 recently, seems to be working but not put through its paces yet. I am still dreaming of it being trouble free, but educating myself prior to hooking up to my Klipsch speakers or bench testing even with my cheap speakers... Definitely don’t want a blowout on my nice set. Using a Fosi Class ‘D at the moment for amp along with my uncles old MCS 3235 for the preamp/phono The MCS has its own issues with the right hand speaker channel being gritty and reduced volume, so it’s just my preamp for now. Thinking maybe I should use the MCS for practice before going into the belly of the pioneer, but so far my one little test I ran with a tiny pioneer bookshelf speaker on the SX-737, it seemed to work fine with my turntable ( didn’t test both speaker channels). More to test in a few weeks when I have time and space on the bench. Thanks for your vids, very educational!!!! Will come in handy for sure ⚡️🔊👍
Thank you! I ran into an issue where one channel was out, there was popping etc on the other channel. Then all of the sudden popping in the amp circuit.
Replaced the differential pairs on the amp board, bias transistors, transistors on the phono board, most of the caps and now dead silent aside from the beautiful music.
You call yourself "A" "H" fix it, I call you "ah" fix it. You are the Bob Ross of electronics repair! Especially amused by the carwash marantz and the business bmw. I was not an electronics repair buff, but I am now! My old man very recently became more interested in repairing electronics after lightning destroyed his beloved sansui aud11 he bought in mid '80s. After watching your videos, even I became interested. You explain things so well, a natural teacher. Thank you for sharing your brain with us! Old man just bought me a marantz 2235 to rehab because I like your videos. Guess now I have to prove that I was paying proper attention and that I was not just mesmerized by YOU.
I'd go through and look for bulging, leaking caps throughout the whole unit. Might as well save everyone the trouble down the road and replace any you see, since you're already in there. 👍
Great video! I have a SX-535 that I need to go through.
Love your videos, you're so good at explaining what is going on and what your doing very clearly that anyone can understand
I am having the exact same problem with an 850. I replaced the same caps and transistors. I lost output after that, but I had to set it aside for something else. I’m going back in to work tomorrow and will double check every thing. Your video mad me feel confident I did the right things. I must just have a bad soder somewhere.
I always shotgun those old Elna caps for that exact reason. They bulge and fail from the bottom and don’t bulge from the top, so visual inspections aren’t reliable with them. I’m not super worried if a cap drifts slightly out of spec, old caps do that, but with the Elnas, they’re silent killers and I change them all out as preventative maintenance.
Pioneer uses some Mitsubishi transistors that had some batches with manufacturing issues. From what I gather, there were some mistakes made with making sure the die was properly sealed allowing corrosion starting on the leads to get all the way through the package. The ones I know off the top of my head were 2SA725/726, ad their compliments 2SC1312/1313. There are a few others. A good way to test for this issue is with a hot air gun to replicate the issue and a cold air spray often makes it go away. My SX737 had two of its input transistors with this issue and it did cause it to go into protection! I found several leaking caps, and did a full recap on mine along with a couple of other routine maintenance items!
Cool. Why not just swap out the 4 other 50 year old caps?
I am a rookie at repair. So far just deoxed a few pieces and rebuilt crossovers on CS-88A speakers. I just subscribed to your channel. Great content So you think it is possible to learn to fix electronics on your own. Just watching your channel and doing small jobs.
Definitely possible. I did with the help of a mentor, not sure I'd be where I am today without them. My goal in making these videos is to try to help others learn, so hopefully they help you! Definitely watch other stuff as well though. I'm not an expert.
Thanks, always a learning experience. Keep up the great videos!
Old electrolytic's are a typical issue in most older gear , check those first !! Also one way to determine visually if a electrolytic is going bad is the plastic cover with the value marking on it will tend to shrink !! Compared to the other capacitors , And often past the top of the aluminum can they are on !
Thank You, always a pleasure watching your videos. Excellent.
Next week's video is quite similar to your SX-636 video!
@@AHFixIt Excellent I will look forward to watching that one, nice interesting fact about using the Mic input as well
I debated buying a sx-636 the other day that needed all new bulbs and a good cleaning. It was $70. I should have made an offer. Would have been a decent project to learn on.
Great video. I still have and use my 737 I bought in ‘76’… had the Pots cleaned the darn thing still sounds great for only 35 watts… And it looks to be in the same condition as this one.
Nice job! Thanks for sharing
What's your method on replacing transistors and knowing which one's to replace with when there's so many options out there?
That was very instructional, thank you.
I have an SX 737 with the same problem... I always though it may be dirty contacts, wasn't sure... It only does it now and then..... I also have an SX 535... Great receivers, both of them...
Man that drove me crazy when you wouldn't stop wriggling that leaky cap. I felt the fear and loathing for the board traces / vias. lol
Terrific video very helpful thank you! I have a question for you. About my MCs receiver.Model 3236.I have a techniques m224 stereo cassette deck hook to it. I also have a Magnavox cdb 492 compact disc player attached to it. It's working fine the only problem I have is allowed popping noise whenever I power down the receiver. I don't know why I can't find an answer. Hoping you would have an answer, a solution, tips that I could follow to correct this problem? Well greatly appreciate your input thank you very much!
I have The same probleem with my Pioneer SX 525 . What transistors do I need for replacement 2SC870 and 2SC871 ?
Great video. I have an SX 737 that has a loud cracking / popping in the left channel at any volume, including all the way down, and any input.
Next Friday's video will show you how to fix it!
@@AHFixIt You're awesome. Can't wait for the video!
Man I wish you lived closer to me, I'd love to get a repair done on my sx-650. Works perfectly most of the time but sometimes, one of the left or right channel will get fair but not cut out totally. Have no idea what could be causing it.
I got a yamaha psr 280 and it works fine but when I plug it into my amplifier it starts making that popping sound my amplifier works great when my keyboard isn't plugged in any thoughts on this thanks brother
sense your replacing the transistors u might as well recap the entire preamp , just my thought, but anyway nice video ,however in one of you past videos u mentioned something about remanufactured parts for a marantz? would u be able to share the link to that company? otherwise i have to thro away a nice marantz
Where are you located, do you work on cassette decks specifically JVC kd 85, nobody near Anderson, Greenville SC will. Belts and hopefully pinch rollers.
This video has helped me alot, I have a Marantz 2220B that im getting a loud popping noise on 1 channel with the volume off. Its there on all inputs with the volume down. I was wondering if it was in the preamp or the power amp but I think you just helped me find my starting point. it will light the dim bulb up everytime it pops... Which strange is it only happens if I attach a speaker to its channel. With no speaker attached the dim bulb stays off, when I attach the speaker to hear the pops the bulb lights up everytime it pops. May have to look into the transistors on that board.
Yup the speaker allows it to complete the circuit thus pull current to light up the bulb
@@AHFixIt much appreciated!
Great trouble shooting video! When you diagnosed it was an issue with the pre amp board, did you just replace all transistors or tested each one to identify the defective component?
He mentions in the video that he did check each one, and they all tested good. He did however mention that even if they test good, doesnt mean they are good, as these were on their way out. Cheap and easy to replace.
Can you provide parts list from Mouser? I’m going to repair my unit but I’m having a hard time figuring out what caps and transistors to order. The 1845 have various letters after Ksc1845. Are they all compatible?
I have an SX 650 with a loud popping after about a half hour of listening. How would I get in touch with you to get it looked at?
I am a big fan of your channel I am 66 I have many fine receivers back in the day could you give me an idea of what it would cost ballpark to completely rebuild all new capacitors and transistors new lamps relay etc. I would like to bring it back to life it has been in storage for 15 years don't presently have anything to listen to. additionally does anybody know a guy like this in Michigan that you could recommend that could do as good of a job as this guy does.
Hi, Do the transitors have to be "gain matched'?
More than 20 years ago, my sanyo receiver had the same issue. I replaced one transistor to fix it.
Bigger caps are more likely to fail, in my experience. Usually because they carry higher current.
i think one way to find a faulty transistor is to point a heat gun at each transistor to heat it up. If the problem only happen after the unit warms up. . Many years ago i use to sell such heating tips to companies doing FA analysis where the IC would only fail after heats up. If you test the transistor cold they will pass
Nice info, thanks for sharing :)
The chassis on the 727 is exactly the same even has the mic input
Where are you located? If close enough I'd like to bring in my Marantz 2270 for servicing.
This is an excellent video, super helpful!
Would you be able to share a good reference guide for replacing transistors? Caps are always straightforward for me, check capacitance, voltage, and polarity and you're good to go but transistors were always a bit more of a mystery... Thanks
ruclips.net/video/9d9T22wxZA8/видео.html here's one from xraytonyb. They're a bit of a mystery to me as well!
@@AHFixIt And you just get transistor packs just like capacitor kits?
Not sure what you mean by transistor packs and capacitor kits. I buy individual parts from Mouser.com
@@AHFixIt Thank you man, this video you shared is also very helpful. I appreciate you taking the time to answer me
Replacing transistors with different types is hard. There are a lot of confusing parameters. Those low power preamp npn transistors can usually be replaced with bc547 and the like, if you do both channels. Phono stages like this are not only amplifiers but also a complex array of active filters, so the curve might be somewhat off with substitute types. Trial and error or a decent curcuit simulator might be required.
Or you get the originals if you find them, but note that's not always sufficient - like for power output transistors, they still have to be matched to each other and the driver, no two are exactly the same by chance...
It would be valuable to show your process for matching transistors. There are other videos out there for that but at least a quick description of the method would be usefulll. Thanks
I'll do that
Trying to learn electronics I have a Pioneer 424 going to replace all the caps and detox I just got and original 1972 shop manual for it I have no clue what the hell is means. I am lost . I thought it would give you voltage specs at terminals on differenty boards but it doesnt . Tells you what scopes you need and generator doesnt show how to hook it up or even the patterns for each circuit I am lost probably going to chuck it $20 down the drain 😞
Question... I bought a Marantz 2226B and it pops on the right channel when rotating the volume knob. The popping will go away if I rotate the volume up and down a few times, which is weird. Also, the right channel will drop off usually shortly after powering on the stereo and getting one or two songs into a vinyl. Sometimes rotating the volume knob or shutting the unit off and turning it back on quickly will solve the issue, and for the most of the time it won't happen again. Not sure where to start the troubleshooting process.
Sounds like cleaning the controls would be a good place to start
So what’s the video after this one?? My 737 is doing something similar but the speaker on one side is popping and cracking even without any sound on
ruclips.net/video/kZf_U8oQ90k/видео.html
Many transistor leads have turned black with tarnish. That somehow makes them noisy.
You can remove the part from the board, scrape off the tarnish (be sure to get rid of ALL of it) with a sharp blade, and reinstall.
I've done it successfully a few times.
Also, I would most likely have replaced All of the electrolytics on that board at the same time.
This won't work if the oxide has moved up into the transistor body. When that happens, replacement is the only option.
how would tarnish affect anything aren't they joined with solder?
@@simonlinser8286
I wish I had a logical explanation, but it's still a mystery to both me And the man who told me about it.
Just maybe the heat from removing the parts and putting them back in does the trick,
but I really believe the tarnish has a lot to do with the problem.
In any case, there isn't much to lose by trying it, and if it doesn't work you can still replace troublesome transistors anyway.
I own an SX - 939 but instead of load pops it's more like 1-2 sec "scratch" sound that occurs very intermittent while playing an album. And it's not the record, trust me. Any ideas?
Probably the same thing that's happening here
I have an SX838. And it has two phono inputs. Phono one is making noise. Phono two is FINE!
How is that possible? Isn't there just ONE phono pre-amp in the unit. Why would one be problematic and the other sound clean? Thanks. Not a big problem since I can use no. 2 for now until that also fails.
Yes, only one phono preamp. I'd clean the function switch assembly and check grounds. The way it's wired, it wouldn't make sense to hear issues only in one phono input if there was something wrong with the phono preamp.
You should watch Mr. Carlsons lab video's about capacitors, they are most of the time the reason other components go bad.
Hey, maybe the underspec cap along with the overspec cap will cancel each other out! :)
Thanks!
Great info my sx737 is still sounding great but Murphy’s law is always around the corner
focus!
7:50 youve never seen a leaky cap?
I've seen the dried up aftermath but not one actively bubbling like that!
All those old caps is going, they are cheep (except filter caps), just replace them :)
Nice to see you work on Pioneer rather than that Marantz crap all of the time!!!
And the war begins....