I had one of these. Bought it brand new in 1983. It is part of a stack, with the record player on the bottom, amp, radio and tape deck units on top, with everything playing through the amp where the speakers attached. Was a fantastic unit
Good is debatable these days, amplifier is almost 50yrs old and everything degrades. Capacitors are mostly fine still, transistors have drifted too much and needed to be changed / some are known to be problematic. The other resistors, some were a service bulletin, some had failed and the others i changed were in the signal path with high modern high precision resistors to try and improve thermal noise. Was it working before I started, sure. But as I said you get one shot with the VFETs and if something fails absolutely damages them, the amplifier becomes useless unfortunately.
Love your perfectionist approach.2 questions - What's the make of the green soldering iron you're are using so skilfully?As well you've mentioned pairing/coupling of transistors.How would you pair NPN/PNP output ones in a Class 'A' power amplifier[Krell for example].Many thanks in advance.
It’s a Thermaltronics TMT-9000 inductive soldering iron, had it for a decade :) Inductive soldering irons will change your life, no waiting for joints to heat up / turning up or adjusting temperature etc
It is very good, its a GOOT solder sucker, had it for over a decade. It has its bad days but its never has anything replaced on it and should probably get a new one. Only problem is it’s not single handed use but I just use my hip to reload it
Hello! Could you please share a link to the service bulletin you are referring to in the video? The one that I found doesn't have the info about the necessary resistors' parameters for replacement. I believe they are different for each grade of V-FETs? That's why I would really appreciate you sharing the link! I'm starting restoration of my 4650 and will follow your videos thoroughly. Keep it up and good luck!
There are 2 service bulletins, this is the one for the resistors and bias change. Just take it slow and leave out the vfets until you confirm all the voltages and do the service bulletins. The other bulletin covers testing the VFETs and setting the bias voltage to maximum before reinstalling. Link www.robuust.nl/~maarten/forum/Sony%20VFET%20bulletin%20[MAE].pdf
@@whatcouldgowrong7914 Thank you very much, I appreciate it! By any chance, do you know if any components should be replaced in the TAN-8550? Or is there a same kind of a note for it? According to my research, it all goes down to replacing the VD1221's and recapping + using the correct resistors to match the grade of V-FETs according to the regular manual. Seems kinda strange to me that 4650 and others have some changes and have to have their resistors replaced for the bigger value and the 8550 seemingly does not.
@@musicscratchpony I don’t have any experience with the 8550 (yet) but im sure some people have experience on audiokarma. General practice for me is to replace any adjustment pots and those double diodes at a bare minimum. But if you want to be really really sure the whole unit should be gone through testing transistors, capacitors etc. It used to just be recapping vintage gear but we’re approaching 50yrs old now and transistors are becoming a big problem also with age. I believe the resistor changes were in relation to the bias change and a design modification. It was just a value change but I generally use higher power resistors because technology has shrunk them drastically
Beautiful restoration, the amplifier is stunning indeed. Better than new. I think you could definitely cut way down on the time lapse. I'd much rather see and hear your thoughts on why you are doing what you are doing. Other than that, I loved the entire series on this amp, well done.
@@whatcouldgowrong7914 thank you very much for sharing the information. I have a Sansui AU-717 and Sansui 5050 receiver which I plan to restore soon. Both of those units have that corrosive glue on the board.
Those time lapses are not doing justice to the work. I understand the reasoning behind wanting shorter videos, but I don't mind long good ones. Perhaps showing important details for each section in real time? Or including chapter marks so people can jump these sections if they are bored with details? Anyway, it was my first time watching your work and I need to offer my compliments to a job well done.
I agree, I’ll ponder how I can strike a better balance, split more videos or something, unfortunately I can only go off RU-vid analytics and long videos seem less popular. Thanks 🙏
Hello, i'm also trying to convert my srd7 to be able to drive pro bias stax headphones so could you please make a tutorial or tips as to how you've done it, thanks!
Sure, my original SRD-7 was based on STAX’s original bias design but I actually have a video coming soon for what is hopefully my final design based on current technology. Ill add in some video the original one I built :)
I love your work ethic and attention to detail. Absolutely gorgeous restoration. I could easily watch an hour of your videos (and I'm sure I'm not alone in saying such) so don't shorten too much. Thanks again for another super cool video.
@@whatcouldgowrong7914 I have it too, and can't enjoy my gear unless I know everything is sparkling clean and correct. There's a little of the TV detective Monk in me as well.
I bought one of these amplifiers brand new back in late 1978 for $600AUD if my memory serves me correctly. A friend of mine in the day had the TA8650, much bigger amplifier power wise and it sounded great on a pair of La Scarla Klipsch loudspeakers.
When you speed up the video so much it's not possible to see what you are doing so it gets to be just a blur, I had to skip those bits to get to the commentary because it's kind of annoying trying to figure out what's happening. Having said that I do realise there are people who will run the video at slow speed so they can see as much detail as possible and would prefer to watch a 2 hour video of desoldering, installing and resoldering components !
Hence why I asked the question, it’s not really possible to accomodate every who wants reasonable length videos and time lapses as these videos take place over many hours of work and are already cut down 🙏
@@whatcouldgowrong7914 If you had a second channel showing uncut 4 hour videos of the entire process there are people who would love it ! They would probably complain you didn't upload enough for them too !
Yup capacitor / transistor subs will be shared in the final video once I confirm everything is happy and nothing goes wrong after a burn in / testing. Doesn’t include the resistors but I just took those off the PCB service manual list which was accurate 🙂
mine went into safety mode this morning =( I'm not nearly skilled enough to do this work myself though, so sadly I have to drive many hours to take it to a repair shop where i'll no doubt be bent over the work bench when its time to pay for the repair. Im super bummed, it wasn't even in use when this happened! I was turned on, and left on all the time even though it wasn't actively playing. I think it just got hot or something and now here I am.
@@jacobs7281The brush is Deoxit gold which I use for the contacts and so the fingers stay in place, the lubrcation which only goes on the top latching mechanism is superlube. Can use many things though, just what I use :)
Thanks, that's some fine rejigging work there. I had one of these and it worked really well until some idiot at a party threw a glass of wine into the top plate. As you say the parts are to difficult to obtain and the repair was not economical.
Thanks so much for this useful video.. I have a Luxman DZ-111 which always worked great but now sometimes jumps, I already cleaned the laser's lens with isopropyl alcohol but didn't improve it so decided to dismount the mech assembly and lubricate the guides and the gears as you did and then try to make the calibration (I already downloaded the service manual and did similar things on other Hi-Fi gears), the 5 calibration steps are exactly the same, same procedure, same test disc (I will use a Denon original service test disc which has same 1kHz, 0dB, R & L track), and same everything (apart trimmers and test point names), now after seeing your video I am much more confident and will try soon to rebirth my old CD player. The last two steps (tracking and focus gain adjustment): if you carefully read the procedure and the schematics essentially they are similar and are related to inject a test signal (1kHz 100mVrms) on a test point and trim a variable resistor so that the voltage read on another test point (separated by the first by a resistor) is essentially the same, I think you don't need that special test jig, only two digital AC voltmeters which share same common ground.. but I don't have a test bench's audio oscillator and I think the output of my PC's soundcard is not enough clean to do this job, so will skip the two last steps as you did ;-) So thanks a lot my friend!
Thanks for taking the time to make this video. I was able to adjust a D-112 to make it not skip as easy. I adjusted the focus and tracking gain as you suggested. I can almost bang on it with a hammer now.
@@whatcouldgowrong7914 I found this article today. shows how to make the adjustments using a Lissajous pattern on a scope schematicsforfree.com/files/Audio/Servicing/CD%20Player%20Alignment.pdf
For good signal transfer, speaker terminals without too much mass are a good way to go, not so much metal between the conductor ends, so your solution is a good one. Make sure there are no ferrous parts though. Great fab work.
