How to repair Sansui AU-7700 Integrated amplifier Channel out or weak
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- เผยแพร่เมื่อ 25 พ.ค. 2019
- Another Solid State Sinema challenge, the king of Sansui's. This is the first time I have had one in the shop. After determining the problem was simply bad solder connections, the real feat was getting it apart to allow access to the circuit board. Many cracked connections were discovered. Reflowed the connections and both channels now operate as they should. This was a great learning experience for me. Now the AU-7700 can join the list of amps that I will service. Great to see the classic amps keep on going! Hope you enjoyed this presentation by D-Lab electronics.
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I have a Sansui AU-9500 from 1976 that has never had the cover off. Still is amazing amp.
I have had the same amp since 1974. Cost me CA$750 back in the days of being a starving university student. My Dad thought I was nuts. I was. It did heavy duty as university DJ equipment for 3 years (along with Altec Lansing Voice of the Theatre speakers) and then "retired" to home use only for 40+ years. Works flawlessly, and I love it like an old friend. Meanwhile my 2000-ish HK AVR 7000 just lost 2 channels. The 70s were great years!
I live in Scotland and I have a Sansui AU5900 that I bought 1976. I have the same issue with the sockets round the back being loose. I can still play sound through a CD player on one of the AUX positions and also FM from my TU5900, but my I am unable to play my Sansui SR525 turntable through the two phono sockets as both are very loose. Nice to see what it looks like inside. It does look a fiddly job because of all the screws. Nice to hear the beautiful tone again so I plan to get my old system serviced and show it off. .
@@jewesson Same issue with my HK AVR 7000, now looking into buying the AU-7700 + TU5900. The HK AVR 7000 appears to be solder cracks as wiggling the rca ports indicates problem. Have yet to investigate physically, but research tells me it is the bottom board, and difficult/lengthy access. Love it when it works, a true powerhouse.
@@jewesson I have had my AU-7700 since 1978. I used to DJ house parties with it. Put all the music on my Sony TC-399 reel to reel because I got tired of people messing with my records, and didn't have to worry about requests. Still have the amp, will be my son's after I am gone. I have a set of Altec Lansing Valencia 846A hooked up to my Heathkit tube monoblocks in the family room. Always wanted the VOT, but they are big, even for a house.
So nice to see how well built these old Japanese amps were built. Friggin smashing job on troubleshooting and explaining the facts of customer amp repair. Keep on a rockin' Terry, and say "Hi" to Marsha for me, you're a lucky dude.
I bought an Sansui AU7900 with a couple of slightly bent heat sinks. I was able to get them back in shape and looks almost perfect. The Phono channels were doing exactly as you described. The fix was exactly the same, but to get to it was a lot simpler. Thanks for the video.
Well done, Terry!! Thank you for your service too!
Nice Terry! Following orders. Sansui made some outstanding amplifiers back in the day. B2300 sound quality still impresses me to this day. Servicing some of the high end Sansui's is complicated, reminds me of working on an old Jaguar.
great vids terry, thanks for your shares, not many people do this stuff anymore, you have a great utube voice easy to hear, easy to understand, hopefully your vids will help to keep this art alive
You're a nice guy and a very competent and honest technician, thanks for sharing!
Great video! It fit to a T for my problem on my AU-5500. Same channel (Right), same mode (Aux 1), and same problem (intermittent). I watched this three times before I got into my amp ---- my first reflow of a PCB ever. But every works perfectly now. Thanks again!
Had the same problem on the same unit. Turned out to be those molex plugs where corroded and the solder joints on the RCA plugs . Changed all the caps while I was in there . This is an amazing sounding unit .
LOL! Now I know why you rather work on Tube gear, rather than these S.S. nightmare(ish) printing boards and tiny soldering spots.
Great methodology to eliminate possible sources of the problem! I have learn a lot from your videos Terry! Thanks for the inspiration and detailed tutoring.
Only got to this now--excuse my procrastination; I didn't choose wine and crackers; I poured a Stella, had a slice of cheese and some Hard Bite chips. These videos are one of the best things going anywhere ... only I'd like to see a video one or two hours, maybe even a three or four hours, with a possible intermission with some of that music you sometimes engratiate us fans with. An Academy Award might be in the offing.
good job D lab watched alot of videos from you that got me inspired to fix eletronics 😊👍i finally acomplished my first repair
Cool deal man, I hope you have the bug now. We need more people involved in this hobby
i totally agree with you 👍
You guys are so right. Glad that this is getting some attention, at least on youtube.
@@d-labelectronics
It's changed a lot over the decades. I was fixing TVs for neighbors when I was 8-10 years old. Granted, it was mostly checking and replacing tubes (remember the drugstore tube testers?) but I knew the basics of how TVs worked at that age. Guessing because my father bought me books that laid it out and somehow I was able to absorb it. He didn't know TVs himself but he could afford to buy me books. I was five when I built my first crystal radio (direct conversion). So yeah, electronics has been a lifelong hobby.
Me too!😀
Yep, been doing electronics for over 25yrs and still enjoy a challenge of repairing or building audio equipment..
I would say us old techs have a valid skill set..
Yes Sir, would be great if there was money in it!
Wow after all these years problem solved, I got the same one same problem. Thank you .
You are the man! Thanks for fixing another fine piece.....
Great job Terry!
Hello, I have an equal amplifier, inherited from my father, with great sentimental value. With the same problem, thanks, it was an excellent explanation about the problem and how to fix it. I only hope to find in my country someone with your experience so that they can fix it for me. I like your style. Continue following videos. I have a Dual 601 turntable that does not rotate, if you repair a similar one, share it
A trick to lessen stress on the jacks when plugging or unplugging cables: twist the RCA plugs in a rotary fashion as you push them on. Don't wiggle them side-to-side, that's how you stress the solder connections. The rotary motion also tends to wipe dust and oxidation off of the jack and plug..
Nice job.. wow not much for cooling / heatsinks there... but a NICE amp and great to have a look at how it's built. Great that you take a little time to reflow the rest. I'll take that advice and thanks !
My Sony STR-7045 (original owner, parents) from 1973 is awesome af - my daily runner for EVERYTHING (home studio, I am freak guitarist, and all else - since I was born) - just put DC offset to +/- 1 mV from about 30, each channel, yesterday! It screams I tell you, no joke. Part of the reason too is that my main speakers is Marshall cab that I rewired to stereo (try it!!!!!) too. B speakers are 3-way home stereo Sony SS-U 431 AV, modest but kickass nice nonetheless. Anyhow, the RCA connections are not soldered to the board. They are just mounted to the rear of the case, with leads coming off them to the board. I DID have to DeOxit them and get all up in them with Q-Tips to get them perfect but that is much much better design than having to resolder, however easy that may be. Nice video D-Lab!!! I want to somehow put 1/4" jacks for the Aux1 instead, as that would pair lovely with my MOTU Traveler interface - it is in my thoughts to do list. I probably won't do it because of keeping it original, but I want to hahaha.
Greetings Terry,
I have this same amp and have owned it since 1978. Since this time I have been in there at least 3 times to fix the same repeat problem. I got in there by removing the output board underneath, guess there is more than one way to skin a cat. Resoldering won't fix it in the long term, it will fail again. I was thinking of some way to give more support to the jack and relieve the stress on the solder joint. JB weld came to mind, but seemed kind of tacky, excuse the pun. I did fix my son's Hafler 110 preamp by drilling and dremeling the board and putting stud mounted RCA jacks with bus wire jumpers to the board. Never use those monster turbine style interconnects on these amps! I need to get in there and solder it up again, Ughhhh!
I love solid state cinema.
Cracks me up!🐿️
I, also love virtually everything you do, WITH THE GLARING EXCEPTION of drinking white wine. I had an unfortunate encounter with the stuff as a teenager; now I gag at the mere thought of it. I blame my parents. But I digress...
Keep up the great info-tainment, Terry. Sorry for being the drama queen but talking it out eases the nausea...
Got ya man, I actually dislike white wine. For the skit, Solid State Sinema drinks white, Tube amp theater is red. So I take it for the team!
@@d-labelectronics So then I take it you're subconsciously trying to express that transistors make you queasy...? I approve... (also, it follows that hybrid equipment demands rosé....)
Terry. You have GOT to stop making this look so easy! :-) Thumbs up, and thanks again for the content.
Ok, I have watched the whole video. I like this guy! 👍👏🏼
That's a nice piece. Would love to have a refurbished one.
I've got a Carver 900 from the late 80s that could probably use a good recapping.
I'm liking the Solid State Sinema nearly as much as the Tube Amp Theatre ... Cool beans Terry!
Excellent man, Those will remain as D-Lab operating stations. If another theme rolls in, I will have to get room for a new stage! My plan is eventually take over the entire house!
@@d-labelectronics Can't wait! :)
I friggin hate the Suits who told the engineers to put jacks, etc directly on to circuit boards to save money. There should never be an opportunity to put mechanical stress into a circuit board. Jacks should be mounted on a chassis!
Poorly executed design. There is no protection to the cables when they are plugged into the jacks from being wacked by something! The field is too wide and stresses the pc board too easily . Some extra screws between the jacks should have been made to keep that from occurring.
Dumb idea, I agree, I have this same AU-7700 amp and have owned it since 1978. I have had it apart probably 3 times to fix this same repeat problem. My son has a Hafler 110 preamp which suffers the same problem, so I drilled out the rca jacks and put stud mounted rca jacks with jumpers. No room to do this in this Sansui however. Needs it again, weak point of the design. Was thinking about JB weld, but that would not be good engineering either.
Mau contato e sujeira são um os piores problemas que a gente enfrenta......Bom trabalho !!!!!
10:00 Did you see that trace on the circuit board that is cut? The blue shielded wire connects to it. Looks like perhaps it is a factory revision. Will have to look at my AU-7700 when I get it apart again.
love your videos
I own the same one. Have the switches doing the same thing, some of the switches go in and out with one side or both but if I wiggle the switch then its works fine!
another great video/ thanks! what track/artist is that at about 13:18? sounds cool.
I have the same amplifier from my father.. loved the amp and it's sound .. problem is spkr relay engages seconds after amp has done warm up .. can't find schematics to repair..
Put 'sansui au-7700 service manual' into Google. First listing that comes up is a full service manual.
great video! I have one of these AU7700 and it sounds great but also need to solder the aux connections I think. On another note two of the spring type speaker connectors are are broken how hard to replace or fix these?
P
Any chance you might do a service repair one of the great late 1970s Technics, like the SA-800 or SA-1000?
If I run across one, yes sure will
Great fix Terry!!! I love the humor you put in it, or is that from drinking a little wine? No pro .................I love wine tooo....much???
@@d-labelectronics Lorenzo?
Good morning teacher I love your videos go my like always... Marcos from BRAZIL
Nice repair of an all too common problem. The vertical position of the RCA plugs probably caused or exacerbated the condition. Also, I'm sure there's a reason for your deliberate misspelling of "cinema". Something to do with sine waves, perhaps?
Great repair and video ! - I've got a Sansui Z-9000 receiver that's has an intermittent channel , wonder if it's a similar problem?
Best thing to do is tap the boards and see if the issue comes and goes. These old relics grow bad solder connections over time
Deoxit and visual inspection are the basics. Look for poped electrolytic caps or lots of dirt and dust shorting things out. I always have to clean the boards and potentomitors and that usealley is 80% of the time is actually the promble . The other times I replace mica capasitors or orange dip capasitors or I usealley find internally broken wires and replace them. And flux is your best friend just clean off the flux when done. And do not be intimidated by electronics I do not posess any electronic certificates or electro/ mechanical degree of any kind. Unless you count my nartie and ham radio licence. If one man engineered it another man can figure it out. And fyi all a circut board is a flat wire connection between parts so that the electrons can flow and be regulated and +and- biased from one part to the next to get the desired outcome of high frequency low frequency or all 3 hi mid and low witch is fed through a roll off cross over. Witch separates the frequencies. To each channel aka hi mid and subwoofer.
Aside from dirty/ oxidized, intermittent switches and controls, and bad soldering, the output relay is another main source of intermittent channels. Tap it while unit is playing and watch the channels come and go, or dropping level, or become somewhat distorted. If you can play a pure clean 400 Hertz tone through the unit, it'll go from a clean tone to a mosquito-like buzzy whine* when you tap the offending component or area. Polish the contacts of the relay (a pencil eraser or ink eraser works well for this), degrease with pure alcohol or another similar no-residue degreasing solvent, and retension the relay "fingers" slightly if need be. Do not, I repeat do not, spray the relay with Deoxit or any other residue-leaving contact cleaner.
* Sorry Terry, wrong kind of "wine"!
Wow you were Air Force, so just my guess you were either PML, Ground Com or Avionics Com Nav troop? I was an in shop avionics Comp Repair manual test station troop for the F15's back in the 70's and 80's so thanks for serving, Great site you have! heres my question, I have two stereo units that are getting old LOL like me and both starting to have what seams like same type issues you have on this video, one is a Technics SU-V10X with 120 watt per channel I ought in Iceland in 1986 sometimes the output relays fail to switch on when powered on it will have no out power, then at other times when it dose power on and work and I increase the volume to say 1/3 volume or more ( but not all the time) they click off and I loose one and sometimes power to both speakers, so was thinking it may be same issues you just showed here with bad solder connection? the other unit i have is an old Carver 130 watt per channel Receiver, it is really bad very very intermittent, seems that this unit by what I've read is well known to have had a really bad solder joint issue! do you have any advice if maybe I myself should just take them apart and inspect and resolder all the joints to see if that fixes them before, I see about sending them off to be fixed by some unknown repair place, I live up in New England ( Ma) so not sure who up this way would be able to do any repairs on this old stuff, so any suggestions be appreciated.
thanks
Bob
I like the older stereo systems they were built way better in my opinion.
anything from the 80s and older where built tough 😊👍
hi... i have sansui au d33 can you please make a video to repair ... my amp is problem is sound Tranjistar is fail reign to high voltage ... please help to fix this problem..
Was there actually a caareer in thir force that had you repairing amps or what? Did you repair anything else??
I worked on Minuteman and Peacekeeper missile ground support systems
You need to put together a small wine room and equip it with a small sound system. Wish I could have enjoyed a glass before hitting the bench with some of the equipment that used to come into the shop I worked at in the past. Abuse and DIY repairs. Made for a bad day.
This is what Walter white does after breaking bad..still skilled as ever!!! Salute boss.
hola tengo un amplificador sansui modelo su-9500 y el problema que suena como trueno en el audio ambos canales con volumen a cero,nose cual sera esa falla espero que me oriente un poco saludo desde chile
is that wine any good? we should all start sending you some great wines along with the gear
I have yamaha component system but no sound coming out from it it just stock and when i use it it doesnt work whats the problem sir?
Do you hear the speaker relay click approx 5 secs after power ON?
It’s me that sure looks easy. I’m Derk l
Really appreciate you fixing this for me 😁😁😁👍👍
he does a great job takes his time he's very thorough
At 7:50 is the point where my boss would be yelling at me to put some masking tape on the top edge of the front faceplate, and put a towel underneath that rear panel so it doesn't scratch the unit in a place that would be visible to the owner of the unit. It's true that often times I think it'll be a quick fix, and the back panel can sit where it's sitting for a minute, and then I'll be putting the thing back together, so I don't really have to worry about it; but I'm units this old, invariably there's something else wrong that you discover during the course of repairing the most obvious main issues, and therefore the unit stays in a disassembled state, with floppy metal parts tethered by wiring harnesses and laying all over the place, for rather a bit longer than you originally expected or intended.
Trimakasih atas petunjuknya...saya.dari indonesia,jakarta timur.. Saya juga punya amply SANSUI AU-7700, yang saya mau pertanyakan sdh sekian lama ada 15 tahun,amply saya tdk.dihidupkan...masalahnya 1. begitu power ON,timbul distorsi,gresek2,pada out speaker (saya pasang speaker 8ohm x2 )..masalah ke 2 apakah out put speaker Sistem A-B (L &R) ada tegangan keluar 87.4VAC ...apakah ini ada masalah di amply sansui saya..mohon petunjuknya ..trimakasih pak
I remember laughing at the Sansui joke, but you seemed to have a good point at the time, because that one had so much glue on the board components.
made me laugh when you said 10 million screws love watching the videos old school stuff
I notice the chrome like surfaces have that nicotine yellow cast. I clean a lot of cigarette smoke out of vintage electronics. I suspect that the units from the 1960s on have other smoke on them too. ;-) Toss all the knobs in an ultrasonic cleaner with some alcohol for a good soak while you soak up an extra glass of wine! (Ain't I a stinker?)
More sir!
Check the interconnects first!
I have a 5000x that I traded an Ampeg bass amp for in 1972
How long did it take to fix all that?
About 2 hours total, Video shoot added some time
Looks like avionics from Mitsubishi zero, Japanese rainbow steel remembe rs wwII I am sure.
You are the Man Terry! Do you have any fail video's? Is there anything you haven't been able to repair? I doubt it, but it would be funny to see! Take care, Tom
easy amp to fix
I just discovered how good vintage gear can sound BUT I do hate those old fashioned connectors.
Simply stupendous.... seriously...:-)
Like Jeffery, it sounds like any hardware problems with jacks connected directly to circuit boards are going to cause cracking on the PC boards! Bad designs
🙂
How can a cap get pregnant? A leaky dielectric?
👍👍😎✌️🤟
I'm more used to Marantz, this model does not seem very tech friendly
Just remember where Marantz started and then where Sansui is made and by whom.
What's your opinion on the 1985-1990 integria onkyos
I liked the 80-85 series. My all time favorite is the silver face Marantz with gyro tuning, best is the model 2275
@@d-labelectronics ok thanks for the input. Cause I want another onkyo tx 866 and another tx 84 and maby another kenwood ge-1000 equlizer and I can stop collecting. Cause I know as these amps and equlizers get older the price will only go up. And plus I have an obsession with oscilloscopes. And digital scanners . So I figure the only way I can really afford to have all these old and new things is to get my realestate licence. Plus I also want the tyt md- 898 witch is a Chinese digital ham radio when combined with there hotspot can talk to yeasu icom dstar and apco phase 2 and most other digital ham radio formats. I probabley got the modle number wrong on the ham radio but I like to sit and stare at electronics and take them apart and learn about them . But my vintage onkyos only come apart when iam cleaning them or replacing old capasitors or repearing them. So far I really like the old onkyos ever sence my neighbor gave me his old integria tx 870 cause he replaced it with a newer Yamaha. And I was 13 at the time and did not realize what I had. I eather threw it away or I might of given it away to my friend in high school I really do not remember. Knowing myself I probabley gave it away . Cause I still have all my RadioShack CBS from when I was 9. Anyways hopefulley i did not bore you with my history. I only wish that i was smarter when i was younger.
I also have a mid 80's A-8500. Only problem I have ever had was a dud speaker relay. Still use it today and don't ever intend to get rid of it.
Fix Mine!!!! Pleeeez???
3:20
Well done ole man..I could not have done any better.
It does seem however, that old electrolytic caps last longer than the newer design...maybe due to power supplies or composition ?
I gave my old 1975 england version kenwood quad for similar problem..weak front channels and crackles.. but at 75watts per it played wonderfully. I still have the quad vinyl lp s.. keep up the super show.
Cudabigfish in Michigan , USA
Hello Gary, are you going to the Chelsea, MI hamfest? I will be there shooting video
@@d-labelectronics I might..first week of June is sisters memorial and day following is family reunion all in Valpo, In. Busy shortly thereafter with new grandbaby due second week of June..eeehah!. I missed Dayton due to health. Hashnasi just did a review on a G90 hf rig..check it.
Will do Sir, Hope to see you there
Au v7000 sansui amp men
transistor number please. (I am Sri Lanka )
Nice!! Nice to "coast" through your vids... :-) (soon)
ha ha.....sanssewage. anyone remember magnavox? maggotbox was its moniker.
My AU-6600 has a hum when in Phono, a tech I took it to said just use a an external preamp. Eventually I did that, and it does work fine with the Turntable preamp going into Aux-1. Disassembly on these is tough, but let's face it, the RCA input design is awful!
Oh well. My AU-6600 probably needs the treatment shown in the video. Perhaps you would like to see it, Terry? The thing is, this unit sounds even better than the old Marantz 2270 I have. Sansui said 42 Watts/Ch on the 6600 which I guess is RMS.
Drinking golden wine and talking about an AU something-or-other Sansui. Coincidence? I think not!
why not replace all the 45 year old electrolytics?
I have an amp in need of repair - you interested?
Sure, what is the make/model?
Sunn Beta Lead - its something in the preamp around the reverb. The power section works as it should . When the amp is used like a slave amp it rocks but otherwise without the reverb cranked the volume is low.
Oh D-lab you're such a kick in the head XD
Now that's a real Sansui, back when they were made in Japan and not China
Japan
@@user-mv5bu2kk8b Japan
It's always fun to see what you can achieve with a botle of wine (lol):-), as always thumps upp.
Maybe not sewage but not a joy to work on either.
Clink clink goes the wheelie bin
You really should have installed a new henway while you were in there!
How much does it weigh?
@@d-labelectronics Somehow I knew you'd know that one!
Those pregnant caps were probably in their third trimester
yes I hate the google police big deal if you want play a song
Never liked amplifiers where they have the audio input connection facing upwards. Stupidest design ever to collect dust.
Fortunately on the Sansui amplifier I have, AU-20000, they are facing back, like they should!!
Lake Nipissing, some early NAD amplifiers did the same thing, RCA jacks facing upward. Definitely a stupid idea.
I really hope your not drinking alcohol before working with electricity and electronics. That would not be the smartest thing to do as the warning labels say it can impair your ability.
Just part of the presentation
Terry has probably forgotten more about safety than we will ever know. You need a little vino to fix a Sansuiage :)
You rock Man, Careful with the Sansuiage a few snow flakes may melt
i'd gladly have him work on my amp. Maybe not drive my car......
I only stated this because I don't want to see you get hurt. It was not meant as hate speech or "being a snowflake"
Replace that goofy 12AX7 in there.