Nice video and explanation! I saw a 636 yesterday at my local thriftstore for 50 euro's but didn't take it, as I have already plenty of finds, but now I'm having second thoughts 😅
Unfortunately this receiver has some known trouble-makers that just need to go - either to fix faults or for future reliability. When I first turned it on, one of the channels was banging and crackling very badly - this wasn't due to noisy controls but bad transistors. (2SC1451 is a key one that has to go, and 2SA726, 2SC1344 are suspects for going noisy). But yes, I didn't need to replace all of them - the main outputs I think were good, but for me it was partially a case of practice and also for future reliability. If the replacement transistors are suitable equivalents I don't think they change the nature of the sound; I believe most of that comes from replacing capacitors - especially the small electrolytics in the signal path. Because it wasn't working very well to start with I can't really say what it sounded like before everything was changed, I just know it sounds really good now - I'm enjoying listening to everything I have thrown at it so far!
I remember these Pioneer boxes well. Was in the early stages of radio at the time as an intern (1978), but can't remember which made Pink Floyd, or Led Zeppelin sound better. Pioneer, or Maranz? Hmmmm?
Yes - it does take a bit of research; you have to find a modern transistor (or diode) with a similar specification. A really useful starting point is to look at posts from others who are really experts at this - and for this particular receiver I've (now) put a link in the video description to a specific post from MarkTheFixer on AudioKarma. Otherwise it is possible to download data sheets for old and modern transistors and compare the many parameters for a good match; in the case of the two "pass" transistors in the power supply, I went with some I already had in stock (MJE15030) rather than the suggested ones. (many thanks for raising this as it made me realise I needed to put that link in to the description!).
I really didn't fully understand that pre-amp board you installed. Did this increase the gain level of the audio signal from pre-amp section to the amp section? What did that do to the sound.
Hello Ross sure wish I had your knowledge of Electrics I love my separates but alas there just aren't any repair emporiums out there anymore I'm forever asking around, do you know where I could acquire the old rear black & red speaker knobs as shown on the SX636 keep the Vids coming Ta .
Fantastic work on your Pioneer SX-636 receiver. Amazing details. Please share other vintage restorations as you can. Your circuit board additions are very nice as well. I am working on a Pioneer SX-880 currently. Thanks for sharing Ross.
Really wonderful restoration! You went above and beyond for this old beauty and I'm happy to hear you'll be using it a lot now. I have a 636 that I am going to start work on soon so this was a lovely watch. Cheers.
Sounds like you had fun doing this project, would you like to restore my 636 for me ? My mother bought it for me after my father passed away in 1976, I was 13 yrs old at the time. It has a tremendous amount of sentimental value to me as you could imagine.
Hi Ross, I've just rescued my dad's old 636 from being chucked in the skip. He doesn't seem that attached to it, whereas I think it looks great. It's been in his loft since the early 90's so I'm going to give it a good service before I start using it again. If you happen to have a list of the components you bought for the renovation, would it be possible to share them? I've not even taken the top off mine yet. Also, are you going to make the gerbers/schematics for those PCB's available?
Hi, I hope you can get it back in service, they sound really good. For parts, I don't have a full bill of materials as I ordered from a few places as well as using some of my own stock - but I highly recommend the post in this thread on AudioKarma from Mark The Fixer audiokarma.org/forums/index.php?threads/pioneer-sx-636-rushing-sound-on-left-channel.517531/ , which lists suitable replacement components, but I think you will find many of the Mouser part numbers listed will be no longer valid. Then I'm afraid you'll have to trawl through suppliers to see who has what in stock. But you can probably get it going with only some small fixes - I did go a bit overboard with full replacements but it was partially for learning. The main filter capacitors are very likely to be fine. When I got my unit it was popping and banging in one channel but there are some known "replace on sight" small transistors in there that go noisy (again see the Audio Karma thread). The main outputs were fine but for reliability I changed them anyway. I hadn't thought about making the Gerbers available but I am rather caught out by evryone's kind interest in the video - I'll have a think about how to do that. Thank you for watching - and best of luck!
I hope you are going to post more service and repair videos. Film more of the prosess too if you can. Thats the really interesting part. Btw. Im part of a group on fb that focus on audio related Repairs on vintage stuff. If you want to join i can send you the details 😊
Hi Alex thank you for your encouragement, really appreciated. I would like to do some more videos, I am just amazed with some of the time and trouble others have taken to share their knowledge on RU-vid. As with everyone I'm sure, time is the issue - full time shift work (and recovery from it) leaves me little space, but retirement is looming so output may increase in a few years 😊 Thank you also for your kind offer re. fb, I'm not currently on fb (deliberate choice!) but I may look in to restarting it.
@@rossthompson1635 fb is a mess, so i understand why you don't want it. I use it mostly for messenger to keep in touch with people, Marketplace, and discussing repairs. 👍
I'm very sorry but I don't - this is just a hobby at present as I have very little time between work and other commitments. Maybe when I retire.... but that is a few years away. I hope you can find someone to get it working properly again.
Would love to see more vintage audio repairs from you. Greatly enjoyed this one. I have a pioneer SX 737 that I bought in 76 I believe and it’s still going.
Thank you for your kind words and encouragement. I would certainly like to do some more videos - as ever, time between work is the tricky thing, but I have more projects waiting.
Good work. 👍 A little overkill on the lights, because those led lights don't flicker , but you did a good job. The Only caps that goes bad in these are the caps that was bad in yours , the ones right beside the rectifier diodes . the main filter caps goes rarely bad. But swapping out the small caps in the audio path is always good. Im interested in buying the old transistors that are still good from you. If you are interested in selling them.
Thank you 😊 Yes I probably did go a bit overboard with the lights. I notice with some mains LED bulbs I am aware of edge-of-vision flicker and that just made me wary. I'm also quite close to the limit of regulation drop-out with rectified 8V AC and a 7V LDO regulator, but unless you really crank the volume to max the lights don't dip in intensity with the beat. Was it the main output transistors you were interested in? I'm going to hang on to those until I get another project completed, but they may turn out not to be required - I'll bear your interest in mind!
