Technics SA 202 Diagnosis and Repair
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- เผยแพร่เมื่อ 5 ส.ค. 2024
- Follow along as we diagnose and repair a vintage 1980 Technics SA-202 receiver. We examine the power amplifier section, diagnose the faulty STK0029 chips and find many other issues with the receiver. Can we source real Sanyo STK chip replacements or are we working with counterfeits? Does it matter?
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Thanks for sharing. As a kid of 16 , I found this receiver at a swap meet. I think I paid 20 bucks for. I found the out put blows and some one bugged up the circuit board. I installed new heat sinks . They were also missing. Repaired the board , and new out puts. I did get an A that year in radio tv repair. Learned a lot playing around with this stuff. Thanks for sharing. Brought back soon good memories.
Thanks for watching! Sounds like you've had more than 20$ worth of fun!
Free time.,! At a new level
Most complete video on restoring a receiver ever !
"Free" time is right, certainly not doing this for the money, doing it for the fun of it, from the fixing to the filming and beyond! If you enjoy the depth check out Electronics Old and New by Michael Caldeira, has channel is awesome. Thanks for watching!
Amazing video!
YOU NEED TO KEEP DOING VINTAGE STEREO TO,VERY POPULAR
Thanks Tina! I have so many projects lined up it is tough to know where to begin sometimes! Thank you for watching.
It's a typo. I believe the treble center frequency is 10kHz, just like it's predecessor, the SA-200, and many others in the SA-x00 line. I have a SA-202 in my diningroom and a SA-200 in the garage. I do prefer the looks of the SA-200 better. Both treble controls are easy to hear the boost or cut of the 10kHz frequency. I don't think I'd be able to hear it if it was 20kHz.
I've changed a number of the Darlington power packs too. They're pretty tough but can fail.
My favorite is the SA-500. It uses discrete output transistors and is stunning in its looks, features, and performance.
Great analytical video !! Hey, I bet you can fix some of Geddy Lee's classic analog synths !!!
Good point about how competitive the industry was and every penny counts !
Thanks for watching and for your feedback! I would love to fix Geddy Lee's synths for him, have him email me!
Thank for your response. I will take your recommendation. I think that I have the schematic. If yes, I can share with you. Thank a lot.
I own that and the 20000 hz is obviously a misprint. 50 hz is wrong as well. When I adjust the pots, I hear a difference in tone.
Fantastic tutorial. I want to work through our SA-300 with my son and this is such a great orientation. It plays, but left channel seems to be out - although the balance knob doesn’t control either. The volume had a lot of drop out points when we first plugged it in, but it seems to be okay now. Haven’t tested radio or phono inputs.
Thank you for doing this style video. Did you print out the schematic and tape pieces together? Having that there seems like a great idea during trouble shooting.
Ray, Thanks for your comments. The first thing I do whenever I begin working on a piece of gear is get a hold of the service manual and then piece together the schematic and board layout diagrams, using photoshop if I have to stitch them together, and print them on 11x17 paper (tabloid). I then import the schematics into Illustrator and use Illustrator to annotate them, draw coloured lines etc as I go along. You could use Powerpoint or Adobe Acrobat as well. Good luck with your project, sounds like a great father-son time!
I have a SA-400. DC offset seems a bit high to me at 56mv and 61mv. Any ideas where to look for a fix?
This sheet of metal was painted black from the beginning, or maybe it was your idea to paint this sheet of metal?
It seems incredible to me that this sheet metal (radiator) is painted?
How can you tell what class amplifier a receiver is by the schematic?
I just got the technics sa 303 and I just wanted to know what class it is
I just picked up a technics SA 800 hope it’s a better receiver.
Bob, by all accounts the upper end of the SA series are supposed to be pretty good receivers. Unless yours has been subject to abuse it should be pretty good, and with 125 watts or so of power, I doubt it would have spent much time being overdriven. At most a recapping might be in order? Good luck!
I have an SA-230, but find little on any channel showing repairs (left channel is out). Is this unit not worth the trouble??
BruceLynn, Only you can decide if it is worth it. It might not be worth the money in the sense that you might spend more time and energy than it is 'worth', but if you are doing it for fun and enjoy the process of learning and trouble shooting then how can you put a price on that? (Do you mean a Technics SA-R230?) At very least perhaps open it up and see if there is anything obvious? Just be safe!
I have a sa- 101 that's the same as the 202 you are working on. I've found a bad diode d-107 it looks kinda wierd and seems burnt. How to fix it??
David, First thing have a look online for the service manual for the sa-101 and see if it tells you what kind of diode that might be, in all likelihood, either a small signal diode, a rectifier diode or a zener diode. Then search on line for the part number listed in the service manual. It may be obsolete, so then search for 'xyz replacement'. Good luck and thanks for watching!
I have a really nice classic set beautiful condition do u buy
I have a sa-101 which was made up to 1979 and is the same as the sa-202 it has a visibly burnt diode d-107 and the right side has failed with badly any distorted sound these sterios have a very clean powerful sound everything else works the lighting panel could it be fixed or parts
David, I'm sure your SA-101 could be fixed, though it is likely going to need much more than a diode. Unless you are able to do the work yourself or have a good friend willing to do it for you it might fall into the category of 'beyond economical repair'.
I am also trying to repair a Technics SA 200, which only has the right channel properly working while the left channel is not working at all.
I took out both Darlinton Power Pack stk 0029 in order to replace the one from the left output.
Here I have a question, since the stk 0029 is impossible to find in our local market. It is OK if I chose the Darlinton stk 0049?
I saw the Data sheet of this component and the differences are in the Thermal Resistance from 2.4 to 2.0 ªC/W and the Supply Voltage at Rated Power Output from +/- 25.0 to +/- 31 V.
Thanking you in advance for your comments.
Freddy, My understanding is that assuming the STK is the only thing wrong with the amp that replacing a STK0029 with a STK0049 will 'work' but you may run into PSU or thermal limitations. I would suggest replacing both if economically feasible.
@@telefunkian Thank you very much. I also removed from the line of the left channel a total of 21 capacitors and tested them. I found 12 capacitors damaged, out of specification or leaked.
I am planning the re cap of all of them.
I will keep you posted.
This tutorial is excellent. Thank you for posting it. I am working on a Technics SA-303, which is quite identical to the illustration model. It had the dreaded’ powers on, no sound’ disease. I replaced most oh the caps, and even the power filter caps. No joy upon firing it up using the Variac. So, I replaced the STK 1039 packs just today, and will fire it up soon. I am not super confident, since both channels were not making sound. I am hoping it will be the answer. Do you have any ideas before I power it up? Again, thanks for this video- it’s excellent.
Mark, Thanks for watching, for your feedback and question. I would examine the schematic, find the driver transistors that power the STKs and check them with a multimeter, they may have blown as well. They will be a lot less expensive than the STKs! Keep going, I'm sure you will fix it and the feeling of satisfaction will be worth it!
@@telefunkian Thanks for your help. I did use the schematic, and long story short, I powered on the 303, and all inputs are working. I feel great in knowing I brought this receiver back. to life, and I am enjoying listening to its great sound. Thanks again for putting this video up, it gave me confidence to dig deep into the issues related to the SA-303 not working.
@@markdost8421 Excellent outcome! Congratulations!
Great tutorial. I have one problem with my SA505 unit. I tried to connect my speakers with the unit on. Big mistake, I cross the positive and the negative weir and then the received do not by pass the safety light. So, no sound is coming out. What do I need to do to fix the problem?
Jose, I'm afraid I don't have a service manual for the 505 so I will have to speculate. You may have blown the power amp chips, which are STK1060K. These can be found on line or you may be able to find replacement equivalents from NTE or ECG. They are not so common but I think this vendor has some... www.sphere.bc.ca/test/semis.html#catalog. The amp also has a speaker protect circuit that the 202 does not have, but I think it is just a DC detection / protect circuit. Sorry I can't be of any more help. Thanks for watching!
Did you ever get it fixed?
@@jpreza no, I do not found anybody to fix it.
Πολύ καλή περιγραφή και προσεγμένη επισκευή, θα ήθελα αν γίνεται να μάς εξηγήσετε γιατί βραχυκυκλωσε σε αυτό το σημείο τό Darlington ?
Thank you for watching and for your question. It has been a long time since I have looked at the schematics but I believe these darlington power packs short when overdriven, possibly when presented with a load that was itself inadequate in some way, such as a partially shorted speaker voice coil?
OL = open line, not overload 😉
10-4, I should know that but for some reason my brain fills in overload when I see it. Especially when I am trying to talk, do something else and think about what to say next at the same time!
I always wondered what the manufacturers think about this. So I took the time to research this a bit - absolutely pointless, but fun:
- Fluke seems to mostly refer to the OL indication as an "voltage overload" (e. g. Fluke 179 user manual) or "overload input" (189 user manual) in its user manuals. For voltages this certainly makes sense, not as much for resistance, diode mode etc.
- Agilent U1272A: They explain it as "Overload (the reading exceeds the display range)"
- Brymen (BM789) doesn't explain what "OL" stands for
Bench DMM often show more explicit text:
- Agilent 34401A: "OVLD", clearly meaning overload
- Keysight 34465A: "Overload"
- Keithley DMM 6500: "Overflow"
For me the take away is:
- Fluke and Agilent seem to explain it as overload, *not "open line"*
- Open line would be confusing as well, because it has nothing to do with "line" voltage
- For resistance/diode mode it makes sense to interpret it as "open lead"
Why do dims always mispronounce TEK-NIKS !?
Steve, you've got me, what is a 'dim' and am I one? ;) I say TEK-NEEKS, but should it be NICKS? ☺
Your video was informative and educational but with the exception of your ridiculous comment you made of Spain. You stated in your video that you purchased on EBay the AN 7060 diff Amp.from “out of all places Spain” What do you mean “out of all places?” Spain is not technological deprived and is not a backward nation. Spain is one of the most industrialized countries in the world. I don’t find it a surprise that you were able to get the electronic component you needed from Spain.
Well my apologies if I offended you, I meant that it was surprising to me that I found the component I was looking for on the other side of the planet, as opposed to the country it was made in, or an country that is known for its marketing of obsolete chips, such as China, which is a more common source (if not the most common source) of such items. That is what I meant by 'of all places'. I don't believe I implied anything negative about Spain, I certainly didn't mean to! Thanks for watching, I'm glad you enjoyed the rest of the video.